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Jeon SM, Pradeep A, Chang D, McDonough L, Chen Y, Latremoliere A, Crawford LK, Caterina MJ. Skin Reinnervation by Collateral Sprouting Following Spared Nerve Injury in Mice. J Neurosci 2024; 44:e1494232024. [PMID: 38471780 PMCID: PMC11007315 DOI: 10.1523/jneurosci.1494-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 01/15/2024] [Accepted: 02/03/2024] [Indexed: 03/14/2024] Open
Abstract
Following peripheral nerve injury, denervated tissues can be reinnervated via regeneration of injured neurons or collateral sprouting of neighboring uninjured afferents into denervated territory. While there has been substantial focus on mechanisms underlying regeneration, collateral sprouting has received less attention. Here, we used immunohistochemistry and genetic neuronal labeling to define the subtype specificity of sprouting-mediated reinnervation of plantar hindpaw skin in the mouse spared nerve injury (SNI) model, in which productive regeneration cannot occur. Following initial loss of cutaneous afferents in the tibial nerve territory, we observed progressive centripetal reinnervation by multiple subtypes of neighboring uninjured fibers into denervated glabrous and hairy plantar skin of male mice. In addition to dermal reinnervation, CGRP-expressing peptidergic fibers slowly but continuously repopulated denervated epidermis, Interestingly, GFRα2-expressing nonpeptidergic fibers exhibited a transient burst of epidermal reinnervation, followed by a trend towards regression. Presumptive sympathetic nerve fibers also sprouted into denervated territory, as did a population of myelinated TrkC lineage fibers, though the latter did so inefficiently. Conversely, rapidly adapting Aβ fiber and C fiber low threshold mechanoreceptor (LTMR) subtypes failed to exhibit convincing sprouting up to 8 weeks after nerve injury in males or females. Optogenetics and behavioral assays in male mice further demonstrated the functionality of collaterally sprouted fibers in hairy plantar skin with restoration of punctate mechanosensation without hypersensitivity. Our findings advance understanding of differential collateral sprouting among sensory neuron subpopulations and may guide strategies to promote the progression of sensory recovery or limit maladaptive sensory phenomena after peripheral nerve injury.
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Affiliation(s)
- Sang-Min Jeon
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Aishwarya Pradeep
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Dennis Chang
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Leah McDonough
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Yijia Chen
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Alban Latremoliere
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
- Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - LaTasha K Crawford
- Department of Pathological Sciences, University of Wisconsin-Madison School of Veterinary Medicine, Madison, Wisconsin 53706
| | - Michael J Caterina
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
- Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
- Department of Biological Chemistry, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
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Spencer NJ, Kyloh MA, Travis L, Hibberd TJ. Mechanisms underlying the gut-brain communication: How enterochromaffin (EC) cells activate vagal afferent nerve endings in the small intestine. J Comp Neurol 2024; 532:e25613. [PMID: 38625817 DOI: 10.1002/cne.25613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/02/2024] [Accepted: 03/24/2024] [Indexed: 04/18/2024]
Abstract
How the gastrointestinal tract communicates with the brain, via sensory nerves, is of significant interest for our understanding of human health and disease. Enterochromaffin (EC) cells in the gut mucosa release a variety of neurochemicals, including the largest quantity of 5-hydroxytryptamine (5-HT) in the body. How 5-HT and other substances released from EC cells activate sensory nerve endings in the gut wall remains a major unresolved mystery. We used in vivo anterograde tracing from nodose ganglia to determine the spatial relationship between 5-HT synthesizing and peptide-YY (PYY)-synthesizing EC cells and their proximity to vagal afferent nerve endings that project to the mucosa of mouse small intestine. The shortest mean distances between single 5-HT- and PYY-synthesizing EC cells and the nearest vagal afferent nerve endings in the mucosa were 33.1 ± 14.4 µm (n = 56; N = 6) and 70.3 ± 32.3 µm (n = 16; N = 6). No morphological evidence was found to suggest that 5-HT- or PYY-containing EC cells form close morphological associations with vagal afferents endings, or varicose axons of passage. The large distances between EC cells and vagal afferent endings are many hundreds of times greater than those known to underlie synaptic transmission in the nervous system (typically 10-15 nm). Taken together, the findings lead to the inescapable conclusion that communication between 5-HT-containing EC cells and vagal afferent nerve endings in the mucosa of the mouse small intestinal occurs in a paracrine fashion, via diffusion. New and Noteworthy None of the findings here are consistent with a view that close physical contacts occur between 5-HT-containing EC cells and vagal afferent nerve endings in mouse small intestine. Rather, the findings suggest that gut-brain communication between EC cells and vagal afferent endings occurs via passive diffusion. The morphological data presented do not support the view that EC cells are physically close enough to vagal afferent endings to communicate via fast synaptic transmission.
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Affiliation(s)
- Nick J Spencer
- Visceral Neurophysiology Laboratory, Flinders Health and Medical Research Institute & College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, South Australia, Australia
| | - Melinda A Kyloh
- Visceral Neurophysiology Laboratory, Flinders Health and Medical Research Institute & College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, South Australia, Australia
| | - Lee Travis
- Visceral Neurophysiology Laboratory, Flinders Health and Medical Research Institute & College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, South Australia, Australia
| | - Timothy J Hibberd
- Visceral Neurophysiology Laboratory, Flinders Health and Medical Research Institute & College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, South Australia, Australia
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Qin L, Li Q, Li J. Amplified P2X 3 pathway activity in muscle afferent dorsal root ganglion neurons and exercise pressor reflex regulation in hindlimb ischaemia-reperfusion. Exp Physiol 2024; 109:524-534. [PMID: 38213082 PMCID: PMC10988672 DOI: 10.1113/ep091616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 12/12/2023] [Indexed: 01/13/2024]
Abstract
Hindlimb ischaemia-reperfusion (IR) is among the most prominent pathophysiological conditions observed in peripheral artery disease (PAD). An exaggerated arterial blood pressure (BP) response during exercise is associated with an elevated risk of cardiovascular events in individuals with PAD. However, the precise mechanisms leading to this exaggerated BP response are poorly elucidated. The P2X3 signalling pathway, which plays a key role in modifying the exercise pressor reflex (EPR), is the focus of the present study. We determined the regulatory role of P2X3 on the EPR in a rat model of hindlimb IR. In vivo and in vitro approaches were used to determine the expression and functions of P2X3 in muscle afferent nerves and EPR in IR rats. We found that in IR rats there was (1) upregulation of P2X3 protein expression in the L4-6 dorsal root ganglia (DRG); (2) amplified P2X currents in isolated isolectin B4 (IB4)-positive muscle DRG neurons; and (3) amplification of the P2X-mediated BP response. We further verified that both A-317491 and siRNA knockdown of P2X3 significantly decreased the activity of P2X currents in isolated muscle DRG neurons. Moreover, inhibition of muscle afferents' P2X3 receptor using A-317491 was observed to alleviate the exaggerated BP response induced by static muscle contraction and P2X-induced BP response by α,β-methylene ATP injection. P2X3 signalling pathway activity is amplified in muscle afferent DRG neurons in regulating the EPR following hindlimb IR.
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Affiliation(s)
- Lu Qin
- Heart and Vascular InstitutePenn State College of MedicineHersheyPennsylvaniaUSA
| | - Qin Li
- Heart and Vascular InstitutePenn State College of MedicineHersheyPennsylvaniaUSA
| | - Jianhua Li
- Heart and Vascular InstitutePenn State College of MedicineHersheyPennsylvaniaUSA
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Deng X, Huang IS, Williams K, Wainwright ML, Zimba PV, Mozzachiodi R. Role of serotonin in the lack of sensitization caused by prolonged food deprivation in Aplysia. Behav Brain Res 2024; 458:114736. [PMID: 37923220 PMCID: PMC10842817 DOI: 10.1016/j.bbr.2023.114736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 10/12/2023] [Accepted: 10/30/2023] [Indexed: 11/07/2023]
Abstract
Food deprivation may cause neurological dysfunctions including memory impairment. The mollusk Aplysia is a suitable animal model to study prolonged food deprivation-induced memory deficits because it can sustain up to 14 days of food deprivation (14DFD). Sensitization of defensive withdrawal reflexes has been used to illustrate the detrimental effects of 14DFD on memory formation. Under normal feeding conditions (i.e., two days food deprivation, 2DFD), aversive stimuli lead to serotonin (5-HT) release into the hemolymph and neuropil, which mediates sensitization and its cellular correlates including increased excitability of tail sensory neurons (TSNs). Recent studies found that 14DFD prevents both short-term and long-term sensitization, as well as short-term increased excitability of TSNs induced by in vitro aversive training. This study investigated the role of 5-HT in the absence of sensitization and TSN increased excitability under 14DFD. Because 5-HT is synthesized from tryptophan obtained through diet, and its exogeneous application alone induces sensitization and increases TSN excitability, we hypothesized that 1) 5-HT level may be reduced by 14DFD and 2) 5-HT may still induce sensitization and TSN increased excitability in 14DFD animals. Results revealed that 14DFD significantly decreased hemolymph 5-HT level, which may contribute to the lack of sensitization and its cellular correlates, while ganglia 5-HT level was not changed. 5-HT exogenous application induced sensitization in 14DFD Aplysia, albeit smaller than that in 2DFD animals, suggesting that this treatment can only induce partial sensitization in food deprived animals. Under 14DFD, 5-HT increased TSN excitability indistinguishable from that observed under 2DFD. Taken together, these findings characterize 5-HT metabolic deficiency under 14DFD, which may be compensated, at least in part, by 5-HT exogenous application.
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Affiliation(s)
- Xin Deng
- Department of Life Sciences, Texas A&M University - Corpus Christi, Corpus Christi, TX 78412, USA; Center for Coastal Studies, Texas A&M University - Corpus Christi, Corpus Christi, TX 78412, USA.
| | - I-Shuo Huang
- Department of Life Sciences, Texas A&M University - Corpus Christi, Corpus Christi, TX 78412, USA; Center for Coastal Studies, Texas A&M University - Corpus Christi, Corpus Christi, TX 78412, USA
| | - Kourtlin Williams
- Department of Life Sciences, Texas A&M University - Corpus Christi, Corpus Christi, TX 78412, USA
| | - Marcy L Wainwright
- Department of Life Sciences, Texas A&M University - Corpus Christi, Corpus Christi, TX 78412, USA
| | - Paul V Zimba
- Department of Life Sciences, Texas A&M University - Corpus Christi, Corpus Christi, TX 78412, USA; Center for Coastal Studies, Texas A&M University - Corpus Christi, Corpus Christi, TX 78412, USA
| | - Riccardo Mozzachiodi
- Department of Life Sciences, Texas A&M University - Corpus Christi, Corpus Christi, TX 78412, USA.
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Guo T, Liu J, Chen L, Bian Z, Zheng G, Feng B. Sex differences in zymosan-induced behavioral visceral hypersensitivity and colorectal afferent sensitization. Am J Physiol Gastrointest Liver Physiol 2024; 326:G133-G146. [PMID: 38050686 DOI: 10.1152/ajpgi.00081.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 11/22/2023] [Accepted: 11/28/2023] [Indexed: 12/06/2023]
Abstract
Sex differences in visceral nociception have been reported in clinical and preclinical studies, but the potential differences in sensory neural encoding of the colorectum between males and females are not well understood. In this study, we systematically assessed sex differences in colorectal neural encoding by conducting high-throughput optical recordings in intact dorsal root ganglia (DRGs) from control and visceral hypersensitive mice. We found an apparent sex difference in zymosan-induced behavioral visceral hypersensitivity: enhanced visceromotor responses to colorectal distension were observed only in male mice, not in female mice. In addition, a higher number of mechanosensitive colorectal afferents were identified per mouse in the zymosan-treated male group than in the saline-treated male group, whereas the mechanosensitive afferents identified per mouse were comparable between the zymosan- and saline-treated female groups. The increased number of identified afferents in zymosan-treated male mice was predominantly from thoracolumbar (TL) innervation, which agrees with the significant increase in the TL afferent proportion in the zymosan group as compared with the control group in male mice. In contrast, female mice showed no difference in the proportion of colorectal neurons between saline- and zymosan-treated groups. Our results revealed a significant sex difference in colorectal afferent innervation and sensitization in the context of behavioral visceral hypersensitivity, which could drive differential clinical symptoms in male and female patients.NEW & NOTEWORTHY We used high-throughput GCaMP6f recordings to study 2,275 mechanosensitive colorectal afferents in mice. Our results revealed significant sex differences in the zymosan-induced behavioral visceral hypersensitivity, which were present in male but not female mice. Male mice also showed sensitization of colorectal afferents in the thoracolumbar pathway, whereas female mice did not. These findings highlight sex differences in sensory neural anatomy and function of the colorectum, with implications for sex-specific therapies for treating visceral pain.
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Affiliation(s)
- Tiantian Guo
- Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut, United States
| | - Jia Liu
- Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut, United States
| | - Longtu Chen
- Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut, United States
| | - Zichao Bian
- Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut, United States
| | - Guoan Zheng
- Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut, United States
| | - Bin Feng
- Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut, United States
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Alsaadi H, Peller J, Ghasemlou N, Kawaja MD. Immunohistochemical phenotype of sensory neurons associated with sympathetic plexuses in the trigeminal ganglia of adult nerve growth factor transgenic mice. J Comp Neurol 2024; 532:e25563. [PMID: 37986234 DOI: 10.1002/cne.25563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Following peripheral nerve injury, postganglionic sympathetic axons sprout into the affected sensory ganglia and form perineuronal sympathetic plexuses with somata of sensory neurons. This sympathosensory coupling contributes to the onset and persistence of injury-induced chronic pain. We have documented the presence of similar sympathetic plexuses in the trigeminal ganglia of adult mice that ectopically overexpress nerve growth factor (NGF), in the absence of nerve injury. In this study, we sought to further define the phenotype(s) of these trigeminal sensory neurons having sympathetic plexuses in our transgenic mice. Using quantitative immunofluorescence staining analyses, we show that the invading sympathetic axons specifically target sensory somata immunopositive for several biomarkers: NGF high-affinity receptor tyrosine kinase A (trkA), calcitonin gene-related peptide (CGRP), neurofilament heavy chain (NFH), and P2X purinoceptor 3 (P2X3). Based on these phenotypic characteristics, the majority of the sensory somata surrounded by sympathetic plexuses are likely to be NGF-responsive nociceptors (i.e., trkA expressing) that are peptidergic (i.e., CGRP expressing), myelinated (i.e., NFH expressing), and ATP sensitive (i.e., P2X3 expressing). Our data also show that very few sympathetic plexuses surround sensory somata expressing other nociceptive (pain) biomarkers, including substance P and acid-sensing ion channel 3. No sympathetic plexuses are associated with sensory somata that display isolectin B4 binding. Though the cellular mechanisms that trigger the formation of sympathetic plexus (with and without nerve injury) remain unknown, our new observations yield an unexpected specificity with which invading sympathetic axons appear to target a precise subtype of nociceptors. This selectivity likely contributes to pain development and maintenance associated with sympathosensory coupling.
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Affiliation(s)
- Hanin Alsaadi
- Center for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
| | - Jacob Peller
- Center for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
| | - Nader Ghasemlou
- Center for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, Queen's University, Kingston, Ontario, Canada
- Department of Biomedical and Molecular Sciences, School of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Michael D Kawaja
- Center for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
- Department of Biomedical and Molecular Sciences, School of Medicine, Queen's University, Kingston, Ontario, Canada
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Wang Q, Caraballo SG, Rychkov G, McGovern AE, Mazzone SB, Brierley SM, Harrington AM. Comparative localization of colorectal sensory afferent central projections in the mouse spinal cord dorsal horn and caudal medulla dorsal vagal complex. J Comp Neurol 2024; 532:e25546. [PMID: 37837642 DOI: 10.1002/cne.25546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 09/04/2023] [Accepted: 10/03/2023] [Indexed: 10/16/2023]
Abstract
The distal colon and rectum (colorectum) are innervated by spinal and vagal afferent pathways. The central circuits into which vagal and spinal afferents relay colorectal nociceptive information remain to be comparatively assessed. To address this, regional colorectal retrograde tracing and colorectal distension (CRD)-evoked neuronal activation were used to compare the circuits within the dorsal vagal complex (DVC) and dorsal horn (thoracolumbar [TL] and lumbosacral [LS] spinal levels) into which vagal and spinal colorectal afferents project. Vagal afferent projections were observed in the nucleus tractus solitarius (NTS), area postrema (AP), and dorsal motor nucleus of the vagus (DMV), labeled from the rostral colorectum. In the NTS, projections were opposed to catecholamine and pontine parabrachial nuclei (PbN)-projecting neurons. Spinal afferent projections were labeled from rostral through to caudal aspects of the colorectum. In the dorsal horn, the number of neurons activated by CRD was linked to pressure intensity, unlike in the DVC. In the NTS, 13% ± 0.6% of CRD-activated neurons projected to the PbN. In the dorsal horn, at the TL spinal level, afferent input was associated with PbN-projecting neurons in lamina I (LI), with 63% ± 3.15% of CRD-activated neurons in LI projecting to the PbN. On the other hand, at the LS spinal level, only 18% ± 0.6% of CRD-activated neurons in LI projected to the PbN. The collective data identify differences in the central neuroanatomy that support the disparate roles of vagal and spinal afferent signaling in the facilitation and modulation of colorectal nociceptive responses.
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Affiliation(s)
- QingQing Wang
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute, Flinders University, Adelaide, South Australia, Australia
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Sonia Garcia Caraballo
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute, Flinders University, Adelaide, South Australia, Australia
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Grigori Rychkov
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
- School of Biomedicine, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Alice E McGovern
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Stuart B Mazzone
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Stuart M Brierley
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute, Flinders University, Adelaide, South Australia, Australia
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
- School of Biomedicine, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Andrea M Harrington
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute, Flinders University, Adelaide, South Australia, Australia
- Hopwood Centre for Neurobiology, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
- School of Biomedicine, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia
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Erdogan O, Michot B, Xia J, Alabdulaaly L, Yesares Rubi P, Ha V, Chiu IM, Gibbs JL. Neuronal-immune axis alters pain and sensory afferent damage during dental pulp injury. Pain 2024; 165:392-403. [PMID: 37903298 DOI: 10.1097/j.pain.0000000000003029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 06/15/2023] [Indexed: 11/01/2023]
Abstract
ABSTRACT Dental pulp tissue is densely innervated by afferent fibers of the trigeminal ganglion. When bacteria cause dental decay near the pulpal tissue, a strong neuronal and immune response occurs, creating pulpitis, which is associated with severe pain and pulp tissue damage. Neuroimmune interactions have the potential to modulate both the pain and pathological outcome of pulpitis. We first investigated the role of the neuropeptide calcitonin gene-related peptide (CGRP), released from peptidergic sensory afferents, in dental pain and immune responses by using Calca knockout (Calca -/- ) and wild-type (Calca +/+ ) mice, in a model of pulpitis by creating a mechanical exposure of the dental pulp horn. We found that the neuropeptide CGRP, facilitated the recruitment of myeloid cells into the pulp while also increasing spontaneous pain-like behavior 20% to 25% at an early time point. Moreover, when we depleted neutrophils and monocytes, we found that there was 20% to 30% more sensory afferent loss and increased presence of bacteria in deeper parts of the tissue, whereas there was a significant reduction in mechanical pain response scores compared with the control group at a later time point. Overall, we showed that there is a crosstalk between peptidergic neurons and neutrophils in the pulp, modulating the pain and inflammatory outcomes of the disease.
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Affiliation(s)
- Ozge Erdogan
- Department of Restorative Dentistry and Biomaterial Sciences, Harvard School of Dental Medicine, Boston, MA, United States
| | - Benoit Michot
- Department of Restorative Dentistry and Biomaterial Sciences, Harvard School of Dental Medicine, Boston, MA, United States
| | - Jinya Xia
- Department of Immunology, Blavatnik Institute, Harvard Medical School, Boston, MA, United States
| | - Lama Alabdulaaly
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, MA, United States
- Division of Oral Medicine and Dentistry, Brigham and Women's Hospital, Boston, MA, United States
| | - Pilar Yesares Rubi
- Department of Restorative Dentistry and Biomaterial Sciences, Harvard School of Dental Medicine, Boston, MA, United States
| | - Vivian Ha
- Department of Restorative Dentistry and Biomaterial Sciences, Harvard School of Dental Medicine, Boston, MA, United States
| | - Isaac M Chiu
- Department of Immunology, Blavatnik Institute, Harvard Medical School, Boston, MA, United States
| | - Jennifer L Gibbs
- Department of Restorative Dentistry and Biomaterial Sciences, Harvard School of Dental Medicine, Boston, MA, United States
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Housley SN, Gardolinski EA, Nardelli P, Reed J, Rich MM, Cope TC. Mechanosensory encoding in ex vivo muscle-nerve preparations. Exp Physiol 2024; 109:35-44. [PMID: 37119460 PMCID: PMC10613129 DOI: 10.1113/ep090763] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 04/12/2023] [Indexed: 05/01/2023]
Abstract
Our objective was to evaluate an ex vivo muscle-nerve preparation used to study mechanosensory signalling by low threshold mechanosensory receptors (LTMRs). Specifically, we aimed to assess how well the ex vivo preparation represents in vivo firing behaviours of the three major LTMR subtypes of muscle primary sensory afferents, namely type Ia and II muscle spindle (MS) afferents and type Ib tendon organ afferents. Using published procedures for ex vivo study of LTMRs in mouse hindlimb muscles, we replicated earlier reports on afferent firing in response to conventional stretch paradigms applied to non-contracting, that is passive, muscle. Relative to in vivo studies, stretch-evoked firing for confirmed MS afferents in the ex vivo preparation was markedly reduced in firing rate and deficient in encoding dynamic features of muscle stretch. These deficiencies precluded conventional means of discriminating type Ia and II afferents. Muscle afferents, including confirmed Ib afferents were often indistinguishable based on their similar firing responses to the same physiologically relevant stretch paradigms. These observations raise uncertainty about conclusions drawn from earlier ex vivo studies that either attribute findings to specific afferent types or suggest an absence of treatment effects on dynamic firing. However, we found that replacing the recording solution with bicarbonate buffer resulted in afferent firing rates and profiles more like those seen in vivo. Improving representation of the distinctive sensory encoding properties in ex vivo muscle-nerve preparations will promote accuracy in assigning molecular markers and mechanisms to heterogeneous types of muscle mechanosensory neurons.
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Affiliation(s)
- Stephen N. Housley
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
| | | | - Paul Nardelli
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
| | - J'Ana Reed
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
| | - Mark M. Rich
- Department of Neuroscience, Cell Biology and PhysiologyWright State UniversityDaytonOHUSA
| | - Timothy C. Cope
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
- W.H. Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of Technology, Georgia Institute of TechnologyAtlantaGAUSA
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Sas D, Gaudel F, Verdier D, Kolta A. Hyperexcitability of muscle spindle afferents in jaw-closing muscles in experimental myalgia: Evidence for large primary afferents involvement in chronic pain. Exp Physiol 2024; 109:100-111. [PMID: 38103003 PMCID: PMC10988680 DOI: 10.1113/ep090769] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Accepted: 11/30/2023] [Indexed: 12/17/2023]
Abstract
The goals of this review are to improve understanding of the aetiology of chronic muscle pain and identify new targets for treatments. Muscle pain is usually associated with trigger points in syndromes such as fibromyalgia and myofascial syndrome, and with small spots associated with spontaneous electrical activity that seems to emanate from fibers inside muscle spindles in EMG studies. These observations, added to the reports that large-diameter primary afferents, such as those innervating muscle spindles, become hyperexcitable and develop spontaneous ectopic firing in conditions leading to neuropathic pain, suggest that changes in excitability of these afferents might make an important contribution to the development of pathological pain. Here, we review evidence that the muscle spindle afferents (MSAs) of the jaw-closing muscles become hyperexcitable in a model of chronic orofacial myalgia. In these afferents, as in other large-diameter primary afferents in dorsal root ganglia, firing emerges from fast membrane potential oscillations that are supported by a persistent sodium current (INaP ) mediated by Na+ channels containing the α-subunit NaV 1.6. The current flowing through NaV 1.6 channels increases when the extracellular Ca2+ concentration decreases, and studies have shown that INaP -driven firing is increased by S100β, an astrocytic protein that chelates Ca2+ when released in the extracellular space. We review evidence of how astrocytes, which are known to be activated in pain conditions, might, through their regulation of extracellular Ca2+ , contribute to the generation of ectopic firing in MSAs. To explain how ectopic firing in MSAs might cause pain, we review evidence supporting the hypothesis that cross-talk between proprioceptive and nociceptive pathways might occur in the periphery, within the spindle capsule.
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Affiliation(s)
- Dar'ya Sas
- Département de NeurosciencesUniversité de MontréalMontréalQuébecCanada
- Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA)MontréalQuébecCanada
| | - Fanny Gaudel
- Département de NeurosciencesUniversité de MontréalMontréalQuébecCanada
- Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA)MontréalQuébecCanada
| | - Dorly Verdier
- Département de NeurosciencesUniversité de MontréalMontréalQuébecCanada
- Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA)MontréalQuébecCanada
| | - Arlette Kolta
- Département de NeurosciencesUniversité de MontréalMontréalQuébecCanada
- Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA)MontréalQuébecCanada
- Faculté de Médecine DentaireUniversité de MontréalMontréalQuébecCanada
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11
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Park SJ, Zides CG, Beyak MJ. Mechanical activation of vagal afferents involves opposing cation and TREK1 currents and NO regulation. Can J Physiol Pharmacol 2023; 101:521-528. [PMID: 37311256 DOI: 10.1139/cjpp-2022-0345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Vagal afferents convey signals of mechanical stimulation in the gut to the brain, which is essential for the regulation of food intake. However, ion channels sensing mechanical stimuli are not fully understood. This study aimed to examine the ionic currents activated by mechanical stimulation and a possible neuro-modulatory role of nitric oxide on vagal afferents. Nodose neuronal currents and potentials, and intestinal afferent firing by mechanical stimulation were measured by whole-cell patch clamp, and in vitro afferent recording, respectively. Osmotically activated cation and two-pore domain K+ currents were identified in nodose neurons. The membrane potential displayed a biphasic change under hypotonic stimulation. Cation channel-mediated depolarization was followed by a hyperpolarization mediated by K+ channels. The latter was inhibited by l-methionine (TREK1 channel inhibitor) and l-NNA (nitric oxide synthase inhibitor). Correspondingly, mechanical stimulation activated opposing cation and TREK1 currents. NOS inhibition decreased TREK1 currents and potentiated jejunal afferent nerve firing induced by mechanical stimuli. This study suggested a novel activation mechanism of ion channels underlying adaptation under mechanical distension in vagal afferent neurons. The guts' ability to perceive mechanical stimuli is vital in determining how it responds to food intake. The mechanosensation through ion channels could initiate and control gut function.
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Affiliation(s)
- Sung Jin Park
- Gastrointestinal Disease Research Unit, Kingston General Hospital, Queen's University, Kingston, ON, K7L2V7, Canada
| | - Carter G Zides
- Gastrointestinal Disease Research Unit, Kingston General Hospital, Queen's University, Kingston, ON, K7L2V7, Canada
| | - Michael J Beyak
- Gastrointestinal Disease Research Unit, Kingston General Hospital, Queen's University, Kingston, ON, K7L2V7, Canada
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12
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Lee S, Jang IS. Menthol excites dural afferent neurons by inhibiting leak K + conductance in rats. Neurosci Lett 2023; 813:137427. [PMID: 37549867 DOI: 10.1016/j.neulet.2023.137427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 08/02/2023] [Accepted: 08/03/2023] [Indexed: 08/09/2023]
Abstract
Menthol-a natural organic compound-is widely used for relieving various pain conditions including migraine. However, a high dose of menthol reportedly decreases pain thresholds and enhances pain responses. Accordingly, in the present study, we addressed the effect of menthol on the excitability of acutely isolated dural afferent neurons, which were identified with a fluorescent dye, using the whole-cell patch-clamp technique. Under a voltage-clamped condition, menthol altered the holding current levels in a concentration-dependent manner. The menthol-induced current (IMenthol) remained unaffected by the addition of selective transient receptor potential melastatin 8 antagonists. Moreover, the reversal potential of IMenthol was similar to the equilibrium potential of K+. IMenthol was accompanied by an increase in input resistance, thereby suggesting that menthol decreases the leak K+ conductance. Under a current-clamped condition, menthol caused depolarization of the membrane potential and decreased the threshold for the generation of action potential. While the IMenthol was substantially inhibited by 10 μM XE-991, a selective KV7 blocker, the M-current mediated by KV7 was not detected in the nociceptive neurons tested in the present study. Moreover, IMenthol decreased under acidic extracellular pH conditions or in the presence of 3 μM A-1899, a selective K2P3.1 and K2P9.1 blocker. The present results suggest that menthol inhibits leak K+ channels, possibly acid-sensitive two-pore domain K+ channels, thereby increasing the excitability of nociceptive sensory neurons. The resultant increase in neuron excitability may partially be responsible for the pronociceptive effect mediated by high menthol doses.
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Affiliation(s)
- Seungbo Lee
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 41940, Republic of Korea.
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13
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Szőke É, Helyes Z. Molecular Links between Sensory Nerves, Inflammation, and Pain 2.0. Int J Mol Sci 2023; 24:12243. [PMID: 37569621 PMCID: PMC10418333 DOI: 10.3390/ijms241512243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/19/2023] [Accepted: 07/24/2023] [Indexed: 08/13/2023] Open
Abstract
Capsaicin-sensitive peptidergic sensory nerves mediate triple actions: besides transmitting sensory and pain signals to the central nervous system (afferent function), they also have local and systemic efferent functions [...].
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Affiliation(s)
- Éva Szőke
- Department of Pharmacology and Pharmacotherapy, Medical School, Eötvös Loránd Research Network, University of Pécs, Szigeti Str. 12, H-7624 Pécs, Hungary;
- National Laboratory for Drug Research and Development, H-1117 Budapest, Hungary
| | - Zsuzsanna Helyes
- Department of Pharmacology and Pharmacotherapy, Medical School, Eötvös Loránd Research Network, University of Pécs, Szigeti Str. 12, H-7624 Pécs, Hungary;
- National Laboratory for Drug Research and Development, H-1117 Budapest, Hungary
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14
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Lowenstein ED, Ruffault PL, Misios A, Osman KL, Li H, Greenberg RS, Thompson R, Song K, Dietrich S, Li X, Vladimirov N, Woehler A, Brunet JF, Zampieri N, Kühn R, Liberles SD, Jia S, Lewin GR, Rajewsky N, Lever TE, Birchmeier C. Prox2 and Runx3 vagal sensory neurons regulate esophageal motility. Neuron 2023; 111:2184-2200.e7. [PMID: 37192624 DOI: 10.1016/j.neuron.2023.04.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 10/31/2022] [Accepted: 04/24/2023] [Indexed: 05/18/2023]
Abstract
Vagal sensory neurons monitor mechanical and chemical stimuli in the gastrointestinal tract. Major efforts are underway to assign physiological functions to the many distinct subtypes of vagal sensory neurons. Here, we use genetically guided anatomical tracing, optogenetics, and electrophysiology to identify and characterize vagal sensory neuron subtypes expressing Prox2 and Runx3 in mice. We show that three of these neuronal subtypes innervate the esophagus and stomach in regionalized patterns, where they form intraganglionic laminar endings. Electrophysiological analysis revealed that they are low-threshold mechanoreceptors but possess different adaptation properties. Lastly, genetic ablation of Prox2 and Runx3 neurons demonstrated their essential roles for esophageal peristalsis in freely behaving mice. Our work defines the identity and function of the vagal neurons that provide mechanosensory feedback from the esophagus to the brain and could lead to better understanding and treatment of esophageal motility disorders.
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Affiliation(s)
- Elijah D Lowenstein
- Developmental Biology/Signal Transduction, Max Delbrück Center for Molecular Medicine, Berlin, Germany; NeuroCure Cluster of Excellence, CharitéUniversitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Pierre-Louis Ruffault
- Developmental Biology/Signal Transduction, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Aristotelis Misios
- Developmental Biology/Signal Transduction, Max Delbrück Center for Molecular Medicine, Berlin, Germany; NeuroCure Cluster of Excellence, CharitéUniversitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany; Systems Biology of Gene Regulatory Elements, Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Kate L Osman
- Department of Otolaryngology - Head & Neck Surgery, University of Missouri School of Medicine, Columbia, MO, USA
| | - Huimin Li
- The First Affiliated Hospital, Jinan University, Guangzhou, China
| | - Rachel S Greenberg
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Rebecca Thompson
- Department of Otolaryngology - Head & Neck Surgery, University of Missouri School of Medicine, Columbia, MO, USA
| | - Kun Song
- Developmental Biology/Signal Transduction, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Stephan Dietrich
- Development and Function of Neural Circuits, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Xun Li
- Immune Regulation and Cancer, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Nikita Vladimirov
- Systems Biology Imaging, Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Andrew Woehler
- Systems Biology Imaging, Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Jean-François Brunet
- Institut de Biologie de l'ENS (IBENS), Inserm, CNRS, École normale supérieure, PSL Research University, Paris, France
| | - Niccolò Zampieri
- Development and Function of Neural Circuits, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Ralf Kühn
- Genome Engineering & Disease Models, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Stephen D Liberles
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Shiqi Jia
- The First Affiliated Hospital, Jinan University, Guangzhou, China
| | - Gary R Lewin
- Molecular Physiology of Somatic Sensation, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Nikolaus Rajewsky
- Systems Biology of Gene Regulatory Elements, Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Teresa E Lever
- Department of Otolaryngology - Head & Neck Surgery, University of Missouri School of Medicine, Columbia, MO, USA
| | - Carmen Birchmeier
- Developmental Biology/Signal Transduction, Max Delbrück Center for Molecular Medicine, Berlin, Germany; NeuroCure Cluster of Excellence, CharitéUniversitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.
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15
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Pastras CJ, Curthoys IS, Rabbitt RD, Brown DJ. Using macular velocity measurements to relate parameters of bone conduction to vestibular compound action potential responses. Sci Rep 2023; 13:10204. [PMID: 37353559 PMCID: PMC10290084 DOI: 10.1038/s41598-023-37102-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 06/15/2023] [Indexed: 06/25/2023] Open
Abstract
To examine mechanisms responsible for vestibular afferent sensitivity to transient bone conducted vibration, we performed simultaneous measurements of stimulus-evoked vestibular compound action potentials (vCAPs), utricular macula velocity, and vestibular microphonics (VMs) in anaesthetized guinea pigs. Results provide new insights into the kinematic variables of transient motion responsible for triggering mammalian vCAPs, revealing synchronized vestibular afferent responses are not universally sensitive to linear jerk as previously thought. For short duration stimuli (< 1 ms), the vCAP increases magnitude in close proportion to macular velocity and temporal bone (linear) acceleration, rather than other kinematic elements. For longer duration stimuli, the vCAP magnitude switches from temporal bone acceleration sensitive to linear jerk sensitive while maintaining macular velocity sensitivity. Frequency tuning curves evoked by tone-burst stimuli show vCAPs increase in proportion to onset macular velocity, while VMs increase in proportion to macular displacement across the entire frequency bandwidth tested between 0.1 and 2 kHz. The subset of vestibular afferent neurons responsible for synchronized firing and vCAPs have been shown previously to make calyceal synaptic contacts with type I hair cells in the striolar region of the epithelium and have irregularly spaced inter-spike intervals at rest. Present results provide new insight into mechanical and neural mechanisms underlying synchronized action potentials in these sensitive afferents, with clinical relevance for understanding the activation and tuning of neurons responsible for driving rapid compensatory reflex responses.
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Affiliation(s)
- Christopher J Pastras
- Faculty of Science and Engineering, School of Engineering, Macquarie University, Sydney, NSW, 2109, Australia.
- School of Medical Sciences, The University of Sydney, Sydney, NSW, 2050, Australia.
| | - Ian S Curthoys
- Vestibular Research Laboratory, School of Psychology, The University of Sydney, Sydney, NSW, 2050, Australia
| | - Richard D Rabbitt
- Departments of Biomedical Engineering, Otolaryngology and Neuroscience Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Daniel J Brown
- School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, WA, 6102, Australia
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16
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Loutit AJ, Wheat HE, Khamis H, Vickery RM, Macefield VG, Birznieks I. How Tactile Afferents in the Human Fingerpad Encode Tangential Torques Associated with Manipulation: Are Monkeys Better than Us? J Neurosci 2023; 43:4033-4046. [PMID: 37142429 PMCID: PMC10254986 DOI: 10.1523/jneurosci.1305-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 04/14/2023] [Accepted: 04/17/2023] [Indexed: 05/06/2023] Open
Abstract
Dexterous object manipulation depends critically on information about forces normal and tangential to the fingerpads, and also on torque associated with object orientation at grip surfaces. We investigated how torque information is encoded by human tactile afferents in the fingerpads and compared them to 97 afferents recorded in monkeys (n = 3; 2 females) in our previous study. Human data included slowly-adapting Type-II (SA-II) afferents, which are absent in the glabrous skin of monkeys. Torques of different magnitudes (3.5-7.5 mNm) were applied in clockwise and anticlockwise directions to a standard central site on the fingerpads of 34 human subjects (19 females). Torques were superimposed on a 2, 3, or 4 N background normal force. Unitary recordings were made from fast-adapting Type-I (FA-I, n = 39), and slowly-adapting Type-I (SA-I, n = 31) and Type-II (SA-II, n = 13) afferents supplying the fingerpads via microelectrodes inserted into the median nerve. All three afferent types encoded torque magnitude and direction, with torque sensitivity being higher with smaller normal forces. SA-I afferent responses to static torque were inferior to dynamic stimuli in humans, while in monkeys the opposite was true. In humans this might be compensated by the addition of sustained SA-II afferent input, and their capacity to increase or decrease firing rates with direction of rotation. We conclude that the discrimination capacity of individual afferents of each type was inferior in humans than monkeys which could be because of differences in fingertip tissue compliance and skin friction.SIGNIFICANCE STATEMENT We investigated how individual human tactile nerve fibers encode rotational forces (torques) and compared them to their monkey counterparts. Human hands, but not monkey hands, are innervated by a tactile neuron type (SA-II afferents) specialized to encode directional skin strain yet, so far, torque encoding has only been studied in monkeys. We find that human SA-I afferents were generally less sensitive and less able to discriminate torque magnitude and direction than their monkey counterparts, especially during the static phase of torque loading. However, this shortfall in humans could be compensated by SA-II afferent input. This indicates that variation in afferent types might complement each other signaling different stimulus features possibly providing computational advantage to discriminate stimuli.
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Affiliation(s)
- Alastair J Loutit
- Neuroscience Research Australia, Sydney, New South Wales 2031, Australia
- School of Biomedical Sciences, UNSW Sydney, Sydney, New South Wales 2031, Australia
| | - Heather E Wheat
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria 3052, Australia
| | - Heba Khamis
- Neuroscience Research Australia, Sydney, New South Wales 2031, Australia
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, New South Wales 2031, Australia
| | - Richard M Vickery
- Neuroscience Research Australia, Sydney, New South Wales 2031, Australia
- School of Biomedical Sciences, UNSW Sydney, Sydney, New South Wales 2031, Australia
- Bionics and Bio-robotics, Tyree Foundation Institute of Health Engineering, UNSW Sydney, Sydney, New South Wales 2031, Australia
| | - Vaughan G Macefield
- Baker Heart and Diabetes Institute, Melbourne, Victoria 3004, Australia
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria 3052, Australia
- Department of Neuroscience, Monash University, Melbourne, Victoria 3052, Australia
| | - Ingvars Birznieks
- Neuroscience Research Australia, Sydney, New South Wales 2031, Australia
- School of Biomedical Sciences, UNSW Sydney, Sydney, New South Wales 2031, Australia
- Bionics and Bio-robotics, Tyree Foundation Institute of Health Engineering, UNSW Sydney, Sydney, New South Wales 2031, Australia
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17
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Luz LL, Lima S, Fernandes EC, Kokai E, Gomori L, Szucs P, Safronov BV. Contralateral Afferent Input to Lumbar Lamina I Neurons as a Neural Substrate for Mirror-Image Pain. J Neurosci 2023; 43:3245-3258. [PMID: 36948583 PMCID: PMC10162462 DOI: 10.1523/jneurosci.1897-22.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 02/17/2023] [Accepted: 03/09/2023] [Indexed: 03/24/2023] Open
Abstract
Mirror-image pain arises from pathologic alterations in the nociceptive processing network that controls functional lateralization of the primary afferent input. Although a number of clinical syndromes related to dysfunction of the lumbar afferent system are associated with the mirror-image pain, its morphophysiological substrate and mechanism of induction remain poorly understood. Therefore, we used ex vivo spinal cord preparation of young rats of both sexes to study organization and processing of the contralateral afferent input to the neurons in the major spinal nociceptive projection area Lamina I. We show that decussating primary afferent branches reach contralateral Lamina I, where 27% of neurons, including projection neurons, receive monosynaptic and/or polysynaptic excitatory drive from the contralateral Aδ-fibers and C-fibers. All these neurons also received ipsilateral input, implying their involvement in the bilateral information processing. Our data further show that the contralateral Aδ-fiber and C-fiber input is under diverse forms of inhibitory control. Attenuation of the afferent-driven presynaptic inhibition and/or disinhibition of the dorsal horn network increased the contralateral excitatory drive to Lamina I neurons and its ability to evoke action potentials. Furthermore, the contralateral Aβδ-fibers presynaptically control ipsilateral C-fiber input to Lamina I neurons. Thus, these results show that some lumbar Lamina I neurons are wired to the contralateral afferent system whose input, under normal conditions, is subject to inhibitory control. A pathologic disinhibition of the decussating pathways can open a gate controlling contralateral information flow to the nociceptive projection neurons and, thus, contribute to induction of hypersensitivity and mirror-image pain.SIGNIFICANCE STATEMENT We show that contralateral Aδ-afferents and C-afferents supply lumbar Lamina I neurons. The contralateral input is under diverse forms of inhibitory control and itself controls the ipsilateral input. Disinhibition of decussating pathways increases nociceptive drive to Lamina I neurons and may cause induction of contralateral hypersensitivity and mirror-image pain.
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Affiliation(s)
- Liliana L Luz
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- Neuronal Networks Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto 4200-135, Portugal
| | - Susana Lima
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- Neuronal Networks Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto 4200-135, Portugal
| | - Elisabete C Fernandes
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- Neuronal Networks Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto 4200-135, Portugal
| | - Eva Kokai
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen H-4032, Hungary
| | - Lidia Gomori
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen H-4032, Hungary
| | - Peter Szucs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen H-4032, Hungary
- ELKH-DE Neuroscience Research Group, Debrecen H-4032, Hungary
| | - Boris V Safronov
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- Neuronal Networks Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto 4200-135, Portugal
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18
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Metz K, Matos IC, Li Y, Afsharipour B, Thompson CK, Negro F, Quinlan KA, Bennett DJ, Gorassini MA. Facilitation of sensory transmission to motoneurons during cortical or sensory-evoked primary afferent depolarization (PAD) in humans. J Physiol 2023; 601:1897-1924. [PMID: 36916205 PMCID: PMC11037101 DOI: 10.1113/jp284275] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 03/09/2023] [Indexed: 03/16/2023] Open
Abstract
Sensory and corticospinal tract (CST) pathways activate spinal GABAergic interneurons that have axoaxonic connections onto proprioceptive (Ia) afferents that cause long-lasting depolarizations (termed primary afferent depolarization, PAD). In rodents, sensory-evoked PAD is produced by GABAA receptors at nodes of Ranvier in Ia afferents, rather than at presynaptic terminals, and facilitates spike propagation to motoneurons by preventing branch-point failures, rather than causing presynaptic inhibition. We examined in 40 human participants whether putative activation of Ia-PAD by sensory or CST pathways can also facilitate Ia afferent activation of motoneurons via the H-reflex. H-reflexes in several leg muscles were facilitated by prior conditioning from low-threshold proprioceptive, cutaneous or CST pathways, with a similar long-lasting time course (∼200 ms) to phasic PAD measured in rodent Ia afferents. Long trains of cutaneous or proprioceptive afferent conditioning produced longer-lasting facilitation of the H-reflex for up to 2 min, consistent with tonic PAD in rodent Ia afferents mediated by nodal α5-GABAA receptors for similar stimulation trains. Facilitation of H-reflexes by this conditioning was likely not mediated by direct facilitation of the motoneurons because isolated stimulation of sensory or CST pathways did not alone facilitate the tonic firing rate of motor units. Furthermore, cutaneous conditioning increased the firing probability of single motor units (motoneurons) during the H-reflex without increasing their firing rate at this time, indicating that the underlying excitatory postsynaptic potential was more probable, but not larger. These results are consistent with sensory and CST pathways activating nodal GABAA receptors that reduce intermittent failure of action potentials propagating into Ia afferent branches. KEY POINTS: Controlled execution of posture and movement requires continually adjusted feedback from peripheral sensory pathways, especially those that carry proprioceptive information about body position, movement and effort. It was previously thought that the flow of proprioceptive feedback from Ia afferents was only reduced by GABAergic neurons in the spinal cord that sent axoaxonic projections to the terminal endings of sensory axons (termed GABAaxo neurons). Based on new findings in rodents, we provide complementary evidence in humans to suggest that sensory and corticospinal pathways known to activate GABAaxo neurons that project to dorsal parts of the Ia afferent also increase the flow of proprioceptive feedback to motoneurons in the spinal cord. These findings support a new role for spinal GABAaxo neurons in facilitating afferent feedback to the spinal cord during voluntary or reflexive movements.
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Affiliation(s)
- Krista Metz
- Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | - Isabel Concha Matos
- Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | - Yaqing Li
- Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | - Babak Afsharipour
- Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | | | - Francesco Negro
- Clinical and Experimental Sciences, Universita degli Studi di Brescia, Brescia, Italy
| | - Katharina A Quinlan
- George and Anne Ryan Institute for Neuroscience, Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, USA
| | - David J Bennett
- Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | - Monica A Gorassini
- Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
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Li Q, Qin L, Li J. Characteristics of acid-sensing ion channel currents in male rat muscle dorsal root ganglion neurons following ischemia/reperfusion. Physiol Rep 2023; 11:e15654. [PMID: 36967457 PMCID: PMC10040404 DOI: 10.14814/phy2.15654] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 03/07/2023] [Accepted: 03/08/2023] [Indexed: 03/28/2023] Open
Abstract
Peripheral artery diseases (PAD) increases muscle afferent nerve-activated reflex sympathetic nervous and blood pressure responses during exercise (termed as exercise pressor reflex). However, the precise signaling pathways leading to the exaggerated autonomic responses in PAD are undetermined. Considering that limb ischemia/reperfusion (I/R) is a feature of PAD, we determined the characteristics of acid-sensing ion channel (ASIC) currents in muscle dorsal root ganglion (DRG) neurons under the conditions of hindlimb I/R and ischemia of PAD. In particular, we examined ASIC currents in two distinct subpopulations, isolectin B4 -positive, and B4 -negative (IB4+ and IB4-) muscle DRG neurons, linking to glial cell line-derived neurotrophic factor and nerve growth factor. In results, ASIC1a- and ASIC3-like currents were observed in IB4- muscle DRG neurons with a greater percentage of ASIC3-like currents. Hindimb I/R and ischemia did not alter the distribution of ASIC1a and ASIC3 currents with activation of pH 6.7 in IB4+ and IB4- muscle DRG neurons; however, I/R altered the distribution of ASIC3 currents in IB4+ muscle DRG neurons with pH 5.5, but not in IB4- neurons. In addition, I/R and ischemia amplified the density of ASIC3-like currents in IB4- muscle DRG neurons. Our results suggest that a selective subpopulation of muscle afferent nerves should be taken into consideration when ASIC signaling pathways are studied to determine the exercise pressor reflex in PAD.
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Affiliation(s)
- Qin Li
- Heart and Vascular InstituteThe Pennsylvania State University College of MedicineHersheyPennsylvaniaUSA
| | - Lu Qin
- Heart and Vascular InstituteThe Pennsylvania State University College of MedicineHersheyPennsylvaniaUSA
| | - Jianhua Li
- Heart and Vascular InstituteThe Pennsylvania State University College of MedicineHersheyPennsylvaniaUSA
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20
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Blaeser AS, Sugden AU, Zhao J, Carneiro-Nascimento S, Shipley FB, Carrié H, Andermann ML, Levy D. Trigeminal afferents sense locomotion-related meningeal deformations. Cell Rep 2022; 41:111648. [PMID: 36384109 PMCID: PMC9713852 DOI: 10.1016/j.celrep.2022.111648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 08/24/2022] [Accepted: 10/20/2022] [Indexed: 11/18/2022] Open
Abstract
The trigeminal sensory innervation of the cranial meninges is thought to serve a nociceptive function and mediate headache pain. However, the activity of meningeal afferents under natural conditions in awake animals remains unexplored. Here, we used two- and three-dimensional two-photon calcium imaging to track the activity of meningeal afferent fibers in awake mice. Surprisingly, a large subset of afferents was activated during non-noxious conditions such as locomotion. We estimated locomotion-related meningeal deformations and found afferents with distinct dynamics and tuning to various levels of meningeal expansion, compression, shearing, and Z-axis motion. Further, these mechanosensitive afferents were often tuned to distinct directions of meningeal expansion or compression. Thus, in addition to their role in headache-related pain, meningeal sensory neurons track the dynamic mechanical state of the meninges under natural conditions.
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Affiliation(s)
- Andrew S Blaeser
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Arthur U Sugden
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Jun Zhao
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Simone Carneiro-Nascimento
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Frederick B Shipley
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Hanaé Carrié
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Mark L Andermann
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
| | - Dan Levy
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
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21
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Xie Z, Zhang X, Zhao M, Huo L, Huang M, Li D, Zhang S, Cheng X, Gu H, Zhang C, Zhan C, Wang F, Shang C, Cao P. The gut-to-brain axis for toxin-induced defensive responses. Cell 2022; 185:4298-4316.e21. [PMID: 36323317 DOI: 10.1016/j.cell.2022.10.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 08/16/2022] [Accepted: 09/30/2022] [Indexed: 11/11/2022]
Abstract
After ingestion of toxin-contaminated food, the brain initiates a series of defensive responses (e.g., nausea, retching, and vomiting). How the brain detects ingested toxin and coordinates diverse defensive responses remains poorly understood. Here, we developed a mouse-based paradigm to study defensive responses induced by bacterial toxins. Using this paradigm, we identified a set of molecularly defined gut-to-brain and brain circuits that jointly mediate toxin-induced defensive responses. The gut-to-brain circuit consists of a subset of Htr3a+ vagal sensory neurons that transmit toxin-related signals from intestinal enterochromaffin cells to Tac1+ neurons in the dorsal vagal complex (DVC). Tac1+ DVC neurons drive retching-like behavior and conditioned flavor avoidance via divergent projections to the rostral ventral respiratory group and lateral parabrachial nucleus, respectively. Manipulating these circuits also interferes with defensive responses induced by the chemotherapeutic drug doxorubicin. These results suggest that food poisoning and chemotherapy recruit similar circuit modules to initiate defensive responses.
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Affiliation(s)
- Zhiyong Xie
- National Institute of Biological Sciences, Beijing, China; Department of Psychological Medicine, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China.
| | - Xianying Zhang
- National Institute of Biological Sciences, Beijing, China; College of Life Sciences, Beijing Normal University, Beijing, China
| | - Miao Zhao
- National Institute of Biological Sciences, Beijing, China
| | - Lifang Huo
- Innovation Center for Advanced Interdisciplinary Medicine, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Laboratory, Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
| | - Meizhu Huang
- National Institute of Biological Sciences, Beijing, China; Innovation Center for Advanced Interdisciplinary Medicine, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Laboratory, Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
| | - Dapeng Li
- Department of Neurobiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | | | - Xinyu Cheng
- National Institute of Biological Sciences, Beijing, China
| | - Huating Gu
- National Institute of Biological Sciences, Beijing, China
| | - Chen Zhang
- Department of Neurobiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Cheng Zhan
- School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Fengchao Wang
- National Institute of Biological Sciences, Beijing, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China.
| | - Congping Shang
- Innovation Center for Advanced Interdisciplinary Medicine, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Laboratory, Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China.
| | - Peng Cao
- National Institute of Biological Sciences, Beijing, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China.
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22
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Chang YC, Ahmed U, Jayaprakash N, Mughrabi I, Lin Q, Wu YC, Gerber M, Abbas A, Daytz A, Gabalski AH, Ashville J, Dokos S, Rieth L, Datta-Chaudhuri T, Tracey KJ, Guo T, Al-Abed Y, Zanos S. kHz-frequency electrical stimulation selectively activates small, unmyelinated vagus afferents. Brain Stimul 2022; 15:1389-1404. [PMID: 36241025 PMCID: PMC10164362 DOI: 10.1016/j.brs.2022.09.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 09/02/2022] [Accepted: 09/30/2022] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Vagal reflexes regulate homeostasis in visceral organs and systems through afferent and efferent neurons and nerve fibers. Small, unmyelinated, C-type afferents comprise over 80% of fibers in the vagus and form the sensory arc of autonomic reflexes of the gut, lungs, heart and vessels and the immune system. Selective bioelectronic activation of C-afferents could be used to mechanistically study and treat diseases of peripheral organs in which vagal reflexes are involved, but it has not been achieved. METHODS We stimulated the vagus in rats and mice using trains of kHz-frequency stimuli. Stimulation effects were assessed using neuronal c-Fos expression, physiological and nerve fiber responses, optogenetic and computational methods. RESULTS Intermittent kHz stimulation for 30 min activates specific motor and, preferentially, sensory vagus neurons in the brainstem. At sufficiently high frequencies (>5 kHz) and at intensities within a specific range (7-10 times activation threshold, T, in rats; 15-25 × T in mice), C-afferents are activated, whereas larger, A- and B-fibers, are blocked. This was determined by measuring fiber-specific acute physiological responses to kHz stimulus trains, and by assessing fiber excitability around kHz stimulus trains through compound action potentials evoked by probing pulses. Aspects of selective activation of C-afferents are explained in computational models of nerve fibers by how fiber size and myelin shape the response of sodium channels to kHz-frequency stimuli. CONCLUSION kHz stimulation is a neuromodulation strategy to robustly and selectively activate vagal C-afferents implicated in physiological homeostasis and disease, over larger vagal fibers.
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Affiliation(s)
- Yao-Chuan Chang
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Umair Ahmed
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Naveen Jayaprakash
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Ibrahim Mughrabi
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Qihang Lin
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, 2052, Australia
| | - Yi-Chen Wu
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Michael Gerber
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Adam Abbas
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Anna Daytz
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Arielle H Gabalski
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Jason Ashville
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Socrates Dokos
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, 2052, Australia
| | - Loren Rieth
- Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV, 26506, United States
| | - Timir Datta-Chaudhuri
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Kevin J Tracey
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Tianruo Guo
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, 2052, Australia
| | - Yousef Al-Abed
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States
| | - Stavros Zanos
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, 11030, United States; Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY, United States.
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23
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Krotov V, Agashkov K, Krasniakova M, Safronov BV, Belan P, Voitenko N. Segmental and descending control of primary afferent input to the spinal lamina X. Pain 2022; 163:2014-2020. [PMID: 35297816 PMCID: PMC9339045 DOI: 10.1097/j.pain.0000000000002597] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 01/03/2022] [Accepted: 01/20/2022] [Indexed: 02/04/2023]
Abstract
ABSTRACT Despite being involved in a number of functions, such as nociception and locomotion, spinal lamina X remains one of the least studied central nervous system regions. Here, we show that Aδ- and C-afferent inputs to lamina X neurons are presynaptically inhibited by homo- and heterosegmental afferents as well as by descending fibers from the corticospinal tract, dorsolateral funiculus, and anterior funiculus. Activation of descending tracts suppresses primary afferent-evoked action potentials and also elicits excitatory (mono- and polysynaptic) and inhibitory postsynaptic responses in lamina X neurons. Thus, primary afferent input to lamina X is subject to both spinal and supraspinal control being regulated by at least 5 distinct pathways.
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Affiliation(s)
- Volodymyr Krotov
- Departments of Sensory Signaling and
- Molecular Biophysics, Bogomoletz Institute of Physiology, Kyiv, Ukraine
| | | | | | - Boris V. Safronov
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Neuronal Networks Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Pavel Belan
- Molecular Biophysics, Bogomoletz Institute of Physiology, Kyiv, Ukraine
- Kyiv Academic University, Kyiv, Ukraine
| | - Nana Voitenko
- Departments of Sensory Signaling and
- Kyiv Academic University, Kyiv, Ukraine
- Private Institution Dobrobut Academy, Kyiv, Ukraine
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24
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Sukhanova KY, Koirala A, Elmslie KS. Na V1.9 current in muscle afferent neurons is enhanced by substances released during muscle activity. J Neurophysiol 2022; 128:739-750. [PMID: 36043704 PMCID: PMC9512110 DOI: 10.1152/jn.00116.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 11/22/2022] Open
Abstract
Skeletal muscle contraction triggers the exercise pressor reflex (EPR) to regulate the cardiovascular system response to exercise. During muscle contraction, substances are released that generate action potential activity in group III and IV afferents that mediate the EPR. Some of these substances increase afferent activity via G-protein-coupled receptor (GPCR) activation, but the mechanisms are incompletely understood. We were interested in determining if tetrodotoxin-resistant (TTX-R) voltage-dependent sodium channels (NaV) were involved and investigated the effect of a mixture of such compounds (bradykinin, prostaglandin, norepinephrine, and ATP, called muscle metabolites). Using whole cell patch-clamp electrophysiology, we show that the muscle metabolites significantly increased TTX-R NaV currents. The rise time of this enhancement averaged ∼2 min, which suggests the involvement of a diffusible second messenger pathway. The effect of muscle metabolites on the current-voltage relationship, channel activation and inactivation kinetics support NaV1.9 channels as the target for this enhancement. When applied individually at the concentration used in the mixture, only prostaglandin and bradykinin significantly enhanced NaV current, but the sum of these enhancements was <1/3 that observed when the muscle metabolites were applied together. This suggests synergism between the activated GPCRs to enhance NaV1.9 current. When applied at a higher concentration, all four substances could enhance the current, which demonstrates that the GPCRs activated by each metabolite can enhance channel activity. The enhancement of NaV1.9 channel activity is a likely mechanism by which GPCR activation increases action potential activity in afferents generating the EPR.NEW & NOTEWORTHY G-protein-coupled receptor (GPCR) activation increases action potential activity in muscle afferents to produce the exercise pressor reflex (EPR), but the mechanisms are incompletely understood. We provide evidence that NaV1.9 current is synergistically enhanced by application of a mixture of metabolites potentially released during muscle contraction. The enhancement of NaV1.9 current is likely one mechanism by which GPCR activation generates the EPR and the inappropriate activation of the EPR in patients with cardiovascular disease.
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Affiliation(s)
- Khrystyna Yu Sukhanova
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
| | - Ankeeta Koirala
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
| | - Keith S Elmslie
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
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25
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Caldwell A, Grundy L, Harrington AM, Garcia-Caraballo S, Castro J, Bunnett NW, Brierley SM. TGR5 agonists induce peripheral and central hypersensitivity to bladder distension. Sci Rep 2022; 12:9920. [PMID: 35705684 PMCID: PMC9200837 DOI: 10.1038/s41598-022-14195-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 06/02/2022] [Indexed: 11/30/2022] Open
Abstract
The mechanisms underlying chronic bladder conditions such as interstitial cystitis/bladder pain syndrome (IC/BPS) and overactive bladder syndrome (OAB) are incompletely understood. However, targeting specific receptors mediating neuronal sensitivity to specific stimuli is an emerging treatment strategy. Recently, irritant-sensing receptors including the bile acid receptor TGR5, have been identified within the viscera and are thought to play a key role in neuronal hypersensitivity. Here, in mice, we identify mRNA expression of TGR5 (Gpbar1) in all layers of the bladder as well as in the lumbosacral dorsal root ganglia (DRG) and in isolated bladder-innervating DRG neurons. In bladder-innervating DRG neurons Gpbar1 mRNA was 100% co-expressed with Trpv1 and 30% co-expressed with Trpa1. In vitro live-cell calcium imaging of bladder-innervating DRG neurons showed direct activation of a sub-population of bladder-innervating DRG neurons with the synthetic TGR5 agonist CCDC, which was diminished in Trpv1-/- but not Trpa1-/- DRG neurons. CCDC also activated a small percentage of non-neuronal cells. Using an ex vivo mouse bladder afferent recording preparation we show intravesical application of endogenous (5α-pregnan-3β-ol-20-one sulphate, Pg5α) and synthetic (CCDC) TGR5 agonists enhanced afferent mechanosensitivity to bladder distension. Correspondingly, in vivo intravesical administration of CCDC increased the number of spinal dorsal horn neurons that were activated by bladder distension. The enhanced mechanosensitivity induced by CCDC ex vivo and in vivo was absent using Gpbar1-/- mice. Together, these results indicate a role for the TGR5 receptor in mediating bladder afferent hypersensitivity to distension and thus may be important to the symptoms associated with IC/BPS and OAB.
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Affiliation(s)
- Ashlee Caldwell
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute (FHMRI), Flinders University, Bedford Park, South Australia, 5042, Australia
- Hopwood Centre for Neurobiology, Lifelong Health Theme, Level 7, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, 5000, Australia
- Discipline of Medicine, University of Adelaide, Level 7, SAHMRI, North Terrace, Adelaide, South Australia, 5000, Australia
| | - Luke Grundy
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute (FHMRI), Flinders University, Bedford Park, South Australia, 5042, Australia
- Hopwood Centre for Neurobiology, Lifelong Health Theme, Level 7, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, 5000, Australia
| | - Andrea M Harrington
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute (FHMRI), Flinders University, Bedford Park, South Australia, 5042, Australia
- Hopwood Centre for Neurobiology, Lifelong Health Theme, Level 7, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, 5000, Australia
| | - Sonia Garcia-Caraballo
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute (FHMRI), Flinders University, Bedford Park, South Australia, 5042, Australia
- Hopwood Centre for Neurobiology, Lifelong Health Theme, Level 7, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, 5000, Australia
| | - Joel Castro
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute (FHMRI), Flinders University, Bedford Park, South Australia, 5042, Australia
- Hopwood Centre for Neurobiology, Lifelong Health Theme, Level 7, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, 5000, Australia
| | - Nigel W Bunnett
- Department of Molecular Pathobiology, Department of Neuroscience and Physiology, Neuroscience Institute, New York University, New York, NY, USA
| | - Stuart M Brierley
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute (FHMRI), Flinders University, Bedford Park, South Australia, 5042, Australia.
- Hopwood Centre for Neurobiology, Lifelong Health Theme, Level 7, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, 5000, Australia.
- Discipline of Medicine, University of Adelaide, Level 7, SAHMRI, North Terrace, Adelaide, South Australia, 5000, Australia.
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Abstract
The muscle spindle (MS) provides essential sensory information for motor control and proprioception. The Group Ia and II MS afferents are low threshold slowly-adapting mechanoreceptors and report both static muscle length and dynamic muscle movement information. The exact molecular mechanism by which MS afferents transduce muscle movement into action potentials is incompletely understood. This short review will discuss recent evidence suggesting that PIEZO2 is an essential mechanically sensitive ion channel in MS afferents and that vesicle-released glutamate contributes to maintaining afferent excitability during the static phase of stretch. Other mechanically gated ion channels, voltage-gated sodium channels, other ion channels, regulatory proteins, and interactions with the intrafusal fibers are also important for MS afferent mechanosensation. Future studies are needed to fully understand mechanosensation in the MS and whether different complements of molecular mediators contribute to the different response properties of Group Ia and II afferents.
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27
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Wei Y, McGlone FP, Marshall AG, Makdani A, Zou Z, Ren L, Wei G. From skin mechanics to tactile neural coding: Predicting afferent neural dynamics during active touch and perception. IEEE Trans Biomed Eng 2022; 69:3748-3759. [PMID: 35604990 DOI: 10.1109/tbme.2022.3177006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
First order cutaneous neurons allow object recognition, texture discrimination, and sensorimotor feedback. Their function is well-investigated under passive stimulation while their role during active touch or sensorimotor control is understudied. To understand how human perception and sensorimotor controlling strategy depend on cutaneous neural signals under active tactile exploration, the finite element (FE) hand and Izhikevich neural dynamic model were combined to predict the cutaneous neural dynamics and the resulting perception during a discrimination test. Using in-vivo microneurography generated single afferent recordings, 75% of the data was applied for the model optimization and another 25% was used for validation. By using this integrated numerical model, the predicted tactile neural signals of the single afferent fibers agreed well with the microneurography test results, achieving the out-of-sample values of 0.94 and 0.82 for slowly adapting type I (SAI) and fast adapting type I unit (FAI) respectively. Similar discriminating capability with the human subject was achieved based on this computational model. Comparable performance with the published numerical model on predicting the cutaneous neural response under passive stimuli was also presented, ensuring the potential applicability of this multi-level numerical model in studying the human tactile sensing mechanisms during active touch. The predicted population-level 1st order afferent neural signals under active touch suggest that different coding strategies might be applied to the afferent neural signals elicited from different cutaneous neurons simultaneously.
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28
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Fernandes EC, Carlos-Ferreira J, Luz LL, Safronov BV. Presynaptic Interactions between Trigeminal and Cervical Nociceptive Afferents Supplying Upper Cervical Lamina I Neurons. J Neurosci 2022; 42:3587-3598. [PMID: 35318285 PMCID: PMC9053849 DOI: 10.1523/jneurosci.0025-22.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/08/2022] [Accepted: 03/07/2022] [Indexed: 11/21/2022] Open
Abstract
Cervical and trigeminal afferents innervate neighboring cranial territories, and their convergence on upper cervical dorsal horn neurons provides a potential substrate for pain referral in primary headache syndromes. Lamina I neurons are central to this mechanism, as they relay convergent nociceptive input to supraspinal pain centers. Unfortunately, little is known about the interactions between trigeminal and cervical afferents supplying Lamina I neurons. Here, we used rats of both sexes to show that cervical and trigeminal afferents interact via presynaptic inhibition, where monosynaptic inputs to Lamina I neurons undergo unidirectional as well as reciprocal presynaptic control. This means that afferent-driven presynaptic inhibition shapes the way trigeminal and cervical Aδ-fiber and C-fiber input reaches Lamina I projection neurons (PNs) and local-circuit neurons (LCNs). We propose that this inhibition provides a feedforward control of excitatory drive to Lamina I neurons that regulates their convergent and cervical-specific or trigeminal-specific processing modes. As a consequence, disruption of the trigeminal and cervical afferent-driven presynaptic inhibition may contribute to development of primary headache syndromes.SIGNIFICANCE STATEMENT Cervical and trigeminal afferents innervate neighboring cranial territories, and their convergence on upper cervical dorsal horn neurons provides a potential substrate for pain referral in primary headache syndromes. Lamina I neurons are central to this mechanism as they relay convergent nociceptive input to supraspinal pain centers. Here, we show that cervical and trigeminal afferents interact via presynaptic inhibition, where inputs to Lamina I neurons undergo unidirectional as well as reciprocal control. The afferent-driven presynaptic inhibition shapes the trigeminocervical Aδ-fiber and C-fiber input to Lamina I neurons. This inhibition provides control of excitatory drive to Lamina I neurons that regulates their convergent and cervical-specific or trigeminal-specific processing modes. Disruption of this control may contribute to development of primary headache syndromes.
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Affiliation(s)
- Elisabete C Fernandes
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- Neuronal Networks Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto 4200-135, Portugal
| | - José Carlos-Ferreira
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- Neuronal Networks Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto 4200-135, Portugal
| | - Liliana L Luz
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- Neuronal Networks Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto 4200-135, Portugal
| | - Boris V Safronov
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- Neuronal Networks Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto 4200-135, Portugal
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Kim SH, Patil MJ, Hadley SH, Bahia PK, Butler SG, Madaram M, Taylor-Clark TE. Mapping of the Sensory Innervation of the Mouse Lung by Specific Vagal and Dorsal Root Ganglion Neuronal Subsets. eNeuro 2022; 9:ENEURO.0026-22.2022. [PMID: 35365503 PMCID: PMC9015009 DOI: 10.1523/eneuro.0026-22.2022] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 03/10/2022] [Accepted: 03/26/2022] [Indexed: 11/21/2022] Open
Abstract
The airways are densely innervated by sensory afferent nerves, whose activation regulates respiration and triggers defensive reflexes (e.g., cough, bronchospasm). Airway innervation is heterogeneous, and distinct afferent subsets have distinct functional responses. However, little is known of the innervation patterns of subsets within the lung. A neuroanatomical map is critical for understanding afferent activation under physiological and pathophysiological conditions. Here, we quantified the innervation of the mouse lung by vagal and dorsal root ganglion (DRG) sensory subsets defined by the expression of Pirt (all afferents), 5HT3 (vagal nodose afferents), Tac1 (tachykinergic afferents), and transient receptor potential vanilloid 1 channel (TRPV1; defensive/nociceptive afferents) using Cre-mediated reporter expression. We found that vagal afferents innervate almost all conducting airways and project into the alveolar region, whereas DRG afferents only innervate large airways. Of the two vagal ganglia, only nodose afferents project into the alveolar region, but both nodose and jugular afferents innervate conducting airways throughout the lung. Many afferents that project into the alveolar region express TRPV1. Few DRG afferents expressed TRPV1. Approximately 25% of blood vessels were innervated by vagal afferents (many were Tac1+). Approximately 10% of blood vessels had DRG afferents (some were Tac1+), but this was restricted to large vessels. Lastly, innervation of neuroepithelial bodies (NEBs) correlated with the cell number within the bodies. In conclusion, functionally distinct sensory subsets have distinct innervation patterns within the conducting airways, alveoli and blood vessels. Physiologic (e.g., stretch) and pathophysiological (e.g., inflammation, edema) stimuli likely vary throughout these regions. Our data provide a neuroanatomical basis for understanding afferent responses in vivo.
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Affiliation(s)
- Seol-Hee Kim
- Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612
| | - Mayur J Patil
- Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612
| | - Stephen H Hadley
- Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612
| | - Parmvir K Bahia
- Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612
| | - Shane G Butler
- Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612
| | - Meghana Madaram
- Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612
| | - Thomas E Taylor-Clark
- Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612
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30
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Ng KKW, Tee X, Vickery RM, Birznieks I. The Relationship Between Tactile Intensity Perception and Afferent Spike Count is Moderated by a Function of Frequency. IEEE Trans Haptics 2022; 15:14-19. [PMID: 34990370 DOI: 10.1109/toh.2022.3140877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It has been suggested that tactile intensity perception can be explained by a linear function of spike rate weighted by afferent type. Other than relying on mathematical models, verifying this experimentally is difficult due to the frequency tuning of different afferent types and changes in population recruitment patterns with vibrotactile frequency. To overcome these complexities, we used pulsatile mechanical stimuli which activate the same afferent population regardless of the repetition rate (frequency), generating one action potential per pulse. We used trains of different frequencies (20-200 Hz) to investigate perceived intensity. Subjects' magnitude ratings increased with pulse rate up to ∼100 Hz and plateaued beyond this frequency. This was true regardless of pulse amplitude, from small pulses that exclusively activated Pacinian (PC) afferents, to pulses large enough to activate other afferents including slowly adapting. Electrical stimulation, which activates afferents indiscriminately, plateaued at a similar frequency, although not in all subjects. As the plateauing did not depend on indentation magnitude and hence on afferent weights, we propose that the contribution of spike count to intensity perception is weighted by a function of frequency. This may explain why fine textures evoking high frequency vibrations of a small magnitude do not feel disproportionally intense.
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31
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Streeter KA, Sunshine MD, Davenport PW, Fuller DD. Phrenic afferent activation modulates cardiorespiratory output in the adult rat. J Neurophysiol 2021; 126:2091-2103. [PMID: 34788165 PMCID: PMC8715055 DOI: 10.1152/jn.00433.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/10/2021] [Accepted: 11/12/2021] [Indexed: 11/22/2022] Open
Abstract
Phrenic afferents project to brainstem areas responsible for cardiorespiratory control and the mid-cervical spinal cord containing the phrenic motor nucleus. Our purpose was to quantify the impact of small- and large-diameter phrenic afferent activation on phrenic motor output. Anesthetized and ventilated rats received unilateral phrenic nerve stimulation while contralateral phrenic motor output and blood pressure were recorded. Twelve currents of 40-Hz inspiratory-triggered stimulation were delivered (20 s on, 5 min off) to establish current response curves. Stimulation pulse width was varied to preferentially activate large-diameter phrenic afferents (narrow pulse width) and recruit small-diameter fibers (wide pulse width). Contralateral phrenic amplitude was elevated immediately poststimulation at currents above 35 µA for wide and 70 µA for narrow pulse stimulation when compared with animals not receiving stimulation (time controls). Wide pulse width stimulation also increased phrenic burst frequency at currents ≥35 µA, caused a transient decrease in mean arterial blood pressure at currents ≥50 µA, and resulted in a small change in heart rate at 300 µA. Unilateral dorsal rhizotomy attenuated stimulation-induced cardiorespiratory responses indicating that phrenic afferent activation is required. Additional analyses compared phrenic motor amplitude with output before stimulation and showed that episodic activation of phrenic afferents with narrow pulse stimulation can induce short-term plasticity. We conclude that the activation of phrenic afferents 1) enhances contralateral phrenic motor amplitude when large-diameter afferents are activated, and 2) when small-diameter fibers are recruited, the amplitude response is associated with changes in burst frequency and cardiovascular parameters.NEW & NOTEWORTHY Acute, inspiratory-triggered stimulation of phrenic afferents increases contralateral phrenic motor amplitude in adult rats. When small-diameter afferents are recruited, the amplitude response is accompanied by an increase in phrenic burst frequency, a transient decrease in mean arterial blood pressure, and a slight increase in heart rate. Repeated episodes of large-diameter phrenic afferent activation may also be capable of inducing short-term plasticity.
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Affiliation(s)
- Kristi A Streeter
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin
- Center for Research and Rehabilitation, University of Florida, Gainesville, Florida
| | - Michael D Sunshine
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- Center for Research and Rehabilitation, University of Florida, Gainesville, Florida
| | - Paul W Davenport
- Center for Research and Rehabilitation, University of Florida, Gainesville, Florida
- Department of Physiological Sciences, University of Florida, Gainesville, Florida
| | - David D Fuller
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- Center for Research and Rehabilitation, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
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Geramipour A, Danziger ZC. Age is associated with reduced urethral pressure and afferent activity in rat. Physiol Rep 2021; 9:e15107. [PMID: 34755496 PMCID: PMC8578905 DOI: 10.14814/phy2.15107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/05/2021] [Accepted: 09/07/2021] [Indexed: 11/24/2022] Open
Abstract
Age-related changes in the lower urinary tract (LUT) can affect the coordination of reflexes and increase the incidence of bladder disorders in elderly. This study examines the age-related loss of urethral signaling capability by measuring the afferent activity directly. We find that less urethral pressure develops in response to fluid flow in old rats compared to young rats and that pressure and flow evoke less urethral afferent activation. These findings are consistent with our previous study demonstrating that the urethra-to-bladder reflex, which is required for efficient voiding, becomes weaker with age. We measured the pudendal afferent response in young (4-7 months) and old (18-24 months) rats to fluid flow in the urethra across a range of flow rates. We used paraffin embedding and hematoxylin and eosin staining to quantify age-related changes in the sensory branch of the pudendal nerve. Urethral afferent signaling in response to the same urethral flow rates was weaker in older animals. That is, the sensitivity of urethra afferents to flow decreased with age, and higher flow rates were required in older animals to recruit urethra afferents. There was also a reduction in the myelin thickness of pudendal afferents in old rats, which is a possible contributing factor to the sensory activity. Furthermore, the same flow rates evoked less pressure in the urethras of old animals, indicating there is an age-related change of the urethral tissue that reduces the pressure stimulus to which these afferents respond. These results help characterize the underlying changes in LUT system with age.
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Affiliation(s)
- Arezoo Geramipour
- Department of Biomedical EngineeringFlorida International UniversityMiamiFloridaUSA
| | - Zachary C. Danziger
- Department of Biomedical EngineeringFlorida International UniversityMiamiFloridaUSA
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Beekhof GC, Gornati SV, Canto CB, Libster AM, Schonewille M, De Zeeuw CI, Hoebeek FE. Activity of Cerebellar Nuclei Neurons Correlates with ZebrinII Identity of Their Purkinje Cell Afferents. Cells 2021; 10:2686. [PMID: 34685666 PMCID: PMC8534335 DOI: 10.3390/cells10102686] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/24/2021] [Accepted: 09/28/2021] [Indexed: 11/17/2022] Open
Abstract
Purkinje cells (PCs) in the cerebellar cortex can be divided into at least two main subpopulations: one subpopulation that prominently expresses ZebrinII (Z+), and shows a relatively low simple spike firing rate, and another that hardly expresses ZebrinII (Z-) and shows higher baseline firing rates. Likewise, the complex spike responses of PCs, which are evoked by climbing fiber inputs and thus reflect the activity of the inferior olive (IO), show the same dichotomy. However, it is not known whether the target neurons of PCs in the cerebellar nuclei (CN) maintain this bimodal distribution. Electrophysiological recordings in awake adult mice show that the rate of action potential firing of CN neurons that receive input from Z+ PCs was consistently lower than that of CN neurons innervated by Z- PCs. Similar in vivo recordings in juvenile and adolescent mice indicated that the firing frequency of CN neurons correlates to the ZebrinII identity of the PC afferents in adult, but not postnatal stages. Finally, the spontaneous action potential firing pattern of adult CN neurons recorded in vitro revealed no significant differences in intrinsic pacemaking activity between ZebrinII identities. Our findings indicate that all three main components of the olivocerebellar loop, i.e., PCs, IO neurons and CN neurons, operate at a higher rate in the Z- modules.
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Affiliation(s)
- Gerrit C. Beekhof
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands;
| | - Simona V. Gornati
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
| | - Cathrin B. Canto
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands;
| | - Avraham M. Libster
- Edmond & Lily Safra Center for Brain Sciences (ELSC), Department of Neurobiology, Institute of Life Sciences, The Hebrew University, Jerusalem 91904, Israel;
| | - Martijn Schonewille
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
| | - Chris I. De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands;
| | - Freek E. Hoebeek
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
- Department for Developmental Origins of Disease, Wilhelmina Children’s Hospital, Brain Center, University Medical Center Utrecht, 3584 EA Utrecht, The Netherlands
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34
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Biet M, Dansereau M, Sarret P, Dumaine R. The neuronal potassium current I A is a potential target for pain during chronic inflammation. Physiol Rep 2021; 9:e14975. [PMID: 34405579 PMCID: PMC8371350 DOI: 10.14814/phy2.14975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 05/10/2021] [Accepted: 06/25/2021] [Indexed: 11/24/2022] Open
Abstract
Voltage-gated ion channels play a key role in the action potential (AP) initiation and its propagation in sensory neurons. Modulation of their activity during chronic inflammation creates a persistent pain state. In this study, we sought to determine how peripheral inflammation caused by complete Freund's adjuvant (CFA) alters the fast sodium (INa ), L-type calcium (ICaL ), and potassium (IK ) currents in primary afferent fibers to increase nociception. In our model, intraplantar administration of CFA induced mechanical allodynia and thermal hyperalgesia at day 14 post-injection. Using whole-cell patch-clamp recording in dissociated small (C), medium (Aδ), and large-sized (Aβ) rat dorsal root ganglion (DRG) neurons, we found that CFA prolonged the AP duration and increased the amplitude of the tetrodotoxin-resistant (TTX-r) INa in Aβ fibers. In addition, CFA accelerated the recovery of INa from inactivation in C and Aδ nociceptive fibers but enhanced the late sodium current (INaL ) only in Aδ and Aβ neurons. Inflammation similarly reduced the amplitude of ICaL in each neuronal cell type. Fourteen days after injection, CFA reduced both components of IK (IKdr and IA ) in Aδ fibers. We also found that IA was significantly larger in C and Aδ neurons in normal conditions and during chronic inflammation. Our data, therefore, suggest that targeting the transient potassium current IA represents an efficient way to shift the balance toward antinociception during inflammation, since its activation will selectively decrease the AP duration in nociceptive fibers. Altogether, our data indicate that complex interactions between IK , INa , and ICaL reduce pain threshold by concomitantly enhancing the activity of nociceptive neurons and reducing the inhibitory action of Aβ fibers during chronic inflammation.
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MESH Headings
- Action Potentials
- Animals
- Calcium Channels, L-Type/metabolism
- Cells, Cultured
- Ganglia, Spinal/cytology
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/physiology
- Male
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Neurons, Afferent/physiology
- Nociception
- Nociceptive Pain/metabolism
- Nociceptive Pain/physiopathology
- Potassium Channels, Voltage-Gated/metabolism
- Rats
- Rats, Sprague-Dawley
- Sodium Channel Blockers/pharmacology
- Sodium Channels/metabolism
- Tetrodotoxin/pharmacology
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Affiliation(s)
- Michael Biet
- Département de Pharmacologie et PhysiologieInstitut de pharmacologie de SherbrookeCentre de Recherche du Centre Hospitalier Universitaire de SherbrookeFaculté de médecine et des Sciences de la SantéUniversité de SherbrookeSherbrookeQuébecCanada
| | - Marc‐André Dansereau
- Département de Pharmacologie et PhysiologieInstitut de pharmacologie de SherbrookeCentre de Recherche du Centre Hospitalier Universitaire de SherbrookeFaculté de médecine et des Sciences de la SantéUniversité de SherbrookeSherbrookeQuébecCanada
| | - Philippe Sarret
- Département de Pharmacologie et PhysiologieInstitut de pharmacologie de SherbrookeCentre de Recherche du Centre Hospitalier Universitaire de SherbrookeFaculté de médecine et des Sciences de la SantéUniversité de SherbrookeSherbrookeQuébecCanada
| | - Robert Dumaine
- Département de Pharmacologie et PhysiologieInstitut de pharmacologie de SherbrookeCentre de Recherche du Centre Hospitalier Universitaire de SherbrookeFaculté de médecine et des Sciences de la SantéUniversité de SherbrookeSherbrookeQuébecCanada
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35
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Li Q, Qin L, Li J. IL-6 signaling pathway contributes to exercise pressor reflex in rats with femoral artery occlusion in association with Kv4 activity in muscle afferent nerves. Physiol Rep 2021; 9:e14935. [PMID: 34231965 PMCID: PMC8261684 DOI: 10.14814/phy2.14935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 05/26/2021] [Indexed: 12/02/2022] Open
Abstract
Interleukin-6 (IL-6) via trans-signaling pathway plays a role in modifying muscle sensory nerve-exaggerated exercise pressor reflex in rats with ligated femoral arteries, but the underlying mechanisms are poorly understood. It is known that voltage-gated potassium channel subfamily member Kv4 channels contribute to the excitabilities of sensory neurons and neuronal signaling transduction. Thus, in this study, we determined that 1) IL-6 regulates the exaggerated exercise pressor reflex in rats with peripheral artery disease (PAD) induced by femoral artery ligation and 2) Kv4 channels in muscle dorsal root ganglion (DRG) neurons are engaged in the role played by IL-6 trans-signaling pathway. We found that the protein levels of IL-6 and its receptor IL-6R expression were increased in the DRGs of PAD rats with 3-day of femoral artery occlusion. Inhibition of muscle afferents' IL-6 trans-signaling pathway (gp130) by intra-arterial administration of SC144, a gp130 inhibitor, into the hindlimb muscles of PAD rats alleviated blood pressure response to static muscle contraction. On the other hand, we found that 3-day femoral occlusion decreased amplitude of Kv4 currents in rat muscle DRG neurons. The homo IL-6/IL-6Rα fusion protein (H. IL-6/6Rα), but not IL-6 alone significantly inhibited Kv4 currents in muscle DRG neurons; and the effect of H. IL-6/6Rα was largely reverted by SC144. In conclusion, our data suggest that via trans-signaling pathway upregulated IL-6 in muscle afferent nerves by ischemic hindlimb muscles inhibits the activity of Kv4 channels and thus likely leads to adjustments of the exercise pressor reflex in PAD.
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Affiliation(s)
- Qin Li
- Heart and Vascular InstituteThe Pennsylvania State University College of MedicineHersheyPAUSA
| | - Lu Qin
- Heart and Vascular InstituteThe Pennsylvania State University College of MedicineHersheyPAUSA
| | - Jianhua Li
- Heart and Vascular InstituteThe Pennsylvania State University College of MedicineHersheyPAUSA
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36
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Ota H, Takebe H, Mizumura K, Taguchi T. Responses of cutaneous C-fiber afferents and spinal microglia after hindlimb cast immobilization in rats. J Physiol Sci 2021; 71:19. [PMID: 34162322 PMCID: PMC10717157 DOI: 10.1186/s12576-021-00803-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 06/08/2021] [Indexed: 11/10/2022]
Abstract
Previous studies have shown that persistent limb immobilization using a cast increases nociceptive behavior to somatic stimuli in rats. However, the peripheral neural mechanisms of nociception remain unclear. Using single-fiber electrophysiological recordings in vitro, we examined the general characteristics of cutaneous C-fiber afferents in the saphenous nerve and their responsiveness to mechanical and heat stimuli in a rat model of immobilization-induced pain by subjecting the rats to hindlimb cast immobilization for 4 weeks. The mechanical response of C-fibers appeared to increase in the model; however, statistical analysis revealed that neither the response threshold nor the response magnitude was altered. The general characteristics and heat responses of the C-fibers were not altered. The number of microglia and cell diameters significantly increased in the superficial dorsal horn of the lumbar spinal cord. Thus, activated microglia-mediated spinal mechanisms are associated with the induction of nociceptive hypersensitivity in rats after persistent cast immobilization.
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Affiliation(s)
- Hiroki Ota
- Department of Physical Therapy, Faculty of Rehabilitation, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata, 950-3198, Japan
- Institute for Human Movement and Medical Science, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata, 950-3198, Japan
| | - Haruna Takebe
- Department of Physical Therapy, Faculty of Rehabilitation, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata, 950-3198, Japan
| | - Kazue Mizumura
- Department of Physiology, Nihon University School of Dentistry, 1-8-13 Kandasurugadai, Chiyoda-ku, Tokyo, 101-8310, Japan
| | - Toru Taguchi
- Department of Physical Therapy, Faculty of Rehabilitation, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata, 950-3198, Japan.
- Institute for Human Movement and Medical Science, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata, 950-3198, Japan.
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37
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Maltese M, March JR, Bashaw AG, Tritsch NX. Dopamine differentially modulates the size of projection neuron ensembles in the intact and dopamine-depleted striatum. eLife 2021; 10:e68041. [PMID: 33983121 PMCID: PMC8163504 DOI: 10.7554/elife.68041] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 05/12/2021] [Indexed: 12/20/2022] Open
Abstract
Dopamine (DA) is a critical modulator of brain circuits that control voluntary movements, but our understanding of its influence on the activity of target neurons in vivo remains limited. Here, we use two-photon Ca2+ imaging to monitor the activity of direct and indirect-pathway spiny projection neurons (SPNs) simultaneously in the striatum of behaving mice during acute and prolonged manipulations of DA signaling. We find that increasing and decreasing DA biases striatal activity toward the direct and indirect pathways, respectively, by changing the overall number of SPNs recruited during behavior in a manner not predicted by existing models of DA function. This modulation is drastically altered in a model of Parkinson's disease. Our results reveal a previously unappreciated population-level influence of DA on striatal output and provide novel insights into the pathophysiology of Parkinson's disease.
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Affiliation(s)
- Marta Maltese
- Neuroscience Institute, New York University Grossman School of MedicineNew YorkUnited States
- Fresco Institute for Parkinson’s and Movement Disorders, New York University Langone HealthNew YorkUnited States
| | - Jeffrey R March
- Neuroscience Institute, New York University Grossman School of MedicineNew YorkUnited States
- Fresco Institute for Parkinson’s and Movement Disorders, New York University Langone HealthNew YorkUnited States
| | - Alexander G Bashaw
- Neuroscience Institute, New York University Grossman School of MedicineNew YorkUnited States
- Fresco Institute for Parkinson’s and Movement Disorders, New York University Langone HealthNew YorkUnited States
| | - Nicolas X Tritsch
- Neuroscience Institute, New York University Grossman School of MedicineNew YorkUnited States
- Fresco Institute for Parkinson’s and Movement Disorders, New York University Langone HealthNew YorkUnited States
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Pincus AB, Fryer AD, Jacoby DB. Mini review: Neural mechanisms underlying airway hyperresponsiveness. Neurosci Lett 2021; 751:135795. [PMID: 33667601 DOI: 10.1016/j.neulet.2021.135795] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 12/25/2022]
Abstract
Neural changes underly hyperresponsiveness in asthma and other airway diseases. Afferent sensory nerves, nerves within the brainstem, and efferent parasympathetic nerves all contribute to airway hyperresponsiveness. Inflammation plays a critical role in these nerve changes. Chronic inflammation and pre-natal exposures lead to increased airway innervation and structural changes. Acute inflammation leads to shifts in neurotransmitter expression of afferent nerves and dysfunction of M2 muscarinic receptors on efferent nerve endings. Eosinophils and macrophages drive these changes through release of inflammatory mediators. Novel tools, including optogenetics, two photon microscopy, and optical clearing and whole mount microscopy, allow for improved studies of the structure and function of airway nerves and airway hyperresponsiveness.
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Affiliation(s)
- Alexandra B Pincus
- Oregon Health and Science University, 3181 SW Sam Jackson Park Road, BRB 440, Portland, OR, 97239, USA.
| | - Allison D Fryer
- Oregon Health and Science University, 3181 SW Sam Jackson Park Road, BRB 440, Portland, OR, 97239, USA
| | - David B Jacoby
- Oregon Health and Science University, 3181 SW Sam Jackson Park Road, BRB 440, Portland, OR, 97239, USA
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39
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Chang YT, Ling J, Gu JG. Effects of GABA B receptor activation on excitability of IB4-positive maxillary trigeminal ganglion neurons: Possible involvement of TREK2 activation. Mol Pain 2021; 17:17448069211042963. [PMID: 34461754 PMCID: PMC8411610 DOI: 10.1177/17448069211042963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/26/2021] [Accepted: 08/11/2021] [Indexed: 11/16/2022] Open
Abstract
IB4-positive maxillary trigeminal ganglion (TG) neurons are a subtype of afferent neurons involving nociception in orofacial regions, and excitability of these neurons is associated with orofacial nociceptive sensitivity. TREK-2 channel is a member of two-pore domain potassium (K2P) channel family mediating leak K+ currents. It has been shown previously that TREK-2 channel activity can be enhanced following GABAB receptor activation, leading to a reduction of cortical neuron excitability. In the present study, we have characterized TREK-2 channel expression on maxillary TG neurons and investigated the effect of the GABAB agonist baclofen on electrophysiological properties of small-sized maxillary TG neurons of rats. We show with immunohistochemistry that TREK-2 channels are predominantly expressed in small-sized IB4-positive maxillary TG neurons. Patch-clamp recordings on neurons in ex vivo TG preparations show that baclofen hyperpolarizes resting membrane potentials, increases outward leak currents, and decreases input resistances in IB4-positive maxillary TG neurons. Moreover, baclofen significantly reduces action potential (AP) firing in IB4-positive maxillary TG neurons. In contrast, baclofen shows no significant effect on electrophysiological properties of small-sized nociceptive-like and non-nociceptive-like maxillary trigeminal neurons that are IB4-negatve. Our results suggest that TREK-2 channel activity can be enhanced by baclofen, leading to reduced excitability of IB4-positive maxillary TG neurons. This finding provides new insights into the role of TREK-2 and GABAB receptors in controlling nociceptive sensitivity in orofacial regions, which may have therapeutic implications.
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Affiliation(s)
- Ya-Ting Chang
- Department of Anesthesiology and Perioperative
Medicine, University of Alabama at Birmingham, Birmingham, USA
| | - Jennifer Ling
- Department of Anesthesiology and Perioperative
Medicine, University of Alabama at Birmingham, Birmingham, USA
| | - Jianguo G Gu
- Department of Anesthesiology and Perioperative
Medicine, University of Alabama at Birmingham, Birmingham, USA
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Seseña E, Soto E, Bueno J, Vega R. Nociceptin/orphanin FQ peptide receptor mediates inhibition of N-type calcium currents in vestibular afferent neurons of the rat. J Neurophysiol 2020; 124:1605-1614. [PMID: 32966754 DOI: 10.1152/jn.00269.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The vestibular system is modulated by various neuromodulators including opioid peptides. The current study was conducted to determine whether activation of nociceptin/orphanin FQ peptide (NOP) receptors modulates voltage-gated calcium currents and action potential discharge of rat vestibular afferent neurons. We performed whole cell patch-clamp recordings on cultured vestibular afferent neurons from P7-P10 Long-Evans rats. Application of nociceptin/orphanin FQ (N/OFQ), a 17-amino acid neuropeptide that is the endogenous ligand for NOP receptor, inhibits the high-voltage activated (HVA) component of the calcium current in a concentration-dependent manner with a half inhibitory concentration of 26 nM. Said inhibitory action on the calcium current is voltage-dependent, which was made clear by the fact that it was reverted in 80% by a depolarizing prepulse. Furthermore, the effect of N/OFQ was blocked by application of the specific NOP-antagonist UFP101, by preincubation with G-protein blocker pertussis toxin, and by coapplication of the specific N-type calcium-current blocker ω-conotoxin-MVIIA. N/OFQ application causes an increase in the duration and maximum rate of repolarization of action potentials. It also decreases repetitive discharge and discharge elicited by sinusoidal stimulation. These results show that in vestibular afferents, NOP receptor activation inhibits N-type calcium current by activating G proteins, mostly through the Gβγ subunit. This suggests that NOP activation produces a presynaptic modulation of primary vestibular afferent neurons' output into the vestibular nuclei, thus taking part in the integration and gain setting of vestibular information in second-order vestibular nucleus neurons.NEW & NOTEWORTHY Our results show that in primary vestibular afferent neurons, activation of the nociceptin/orphanin FQ peptide receptor inhibits the N-type calcium current by a mechanism mediated by G proteins. We propose that calcium current inhibition modulates neurotransmitter release from vestibular afferents, producing a presynaptic modulation of vestibular input to vestibular nuclei, thus contributing to gain control in the vestibular afferent input.
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Affiliation(s)
- Emmanuel Seseña
- Facultad de Medicina, Benemérita Universidad Autónoma de Puebla, Pue, México
| | - Enrique Soto
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Pue, México
| | - Jesua Bueno
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Pue, México
| | - Rosario Vega
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Pue, México
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Putland R, Rogers L, Giuffrida B, Mensinger A. Anesthetic effects of AQUI-S 20E® (eugenol) on the afferent neural activity of the oyster toadfish (Opsanus tau). Fish Physiol Biochem 2020; 46:2213-2226. [PMID: 32901327 DOI: 10.1007/s10695-020-00874-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/01/2020] [Indexed: 06/11/2023]
Abstract
Anesthesia is used to sedate aquatic animals during transportation or to immobilize them for surgery. However, most studies have focused on the behavioral effects of induction and recovery, without addressing the effect of anesthetic on neural activity. This study investigated the neural response of anterior lateral line afferent fibers in the oyster toadfish, Opsanus tau, during exposure to incremental increases of AQUI-S 20E (0.001-0.006%), to determine if eugenol (the active ingredient of AQUI-S 20E) influences neural activity of the fish lateral line system. Ventilation rate significantly decreased following AQUI-S 20E exposure with the surgical plane of anesthesia reached at 0.003%, characterized by shallow ventilation, equilibrium loss, and no response to tactile stimuli. Spontaneous and evoked firing rates of anterior lateral line fibers also significantly decreased following exposure, although the effect was transitory as neural activity recovered in the majority of fibers (70%) within 30 min of anesthetic withdrawal. While AQUI-S 20E proved effective in inducing the surgical plane of anesthesia without compromising survival, it is not recommended for acute neural preparations due to its depression of neural activity. However, the depression of lateral line sensitivity at low concentrations could play a role in reducing the stress response during fish transport.
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Affiliation(s)
- Rosalyn Putland
- Department of Biology, Swenson Science Building, University of Minnesota Duluth, Duluth, MN, 55812, USA.
- Marine Biological Laboratory, Woods Hole, MA, 02543, USA.
| | - Loranzie Rogers
- Marine Biological Laboratory, Woods Hole, MA, 02543, USA
- Department of Psychology, University of Washington, Seattle, WA, 98195, USA
| | - Beth Giuffrida
- Marine Biological Laboratory, Woods Hole, MA, 02543, USA
- Wareham High School, Wareham, MA, 02571, USA
| | - Allen Mensinger
- Department of Biology, Swenson Science Building, University of Minnesota Duluth, Duluth, MN, 55812, USA
- Marine Biological Laboratory, Woods Hole, MA, 02543, USA
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Abstract
Ophthalmic, maxillary, and mandibular branches of the trigeminal nerve provide sensory innervation to orofacial tissues. Trigeminal sensory neurons respond to a diverse array of sensory stimuli to generate distinct sensations, including thermosensation, mechanosensation, itching, and pain. These sensory neurons also detect the distinct sharpness or pungency of many foods and beverages. This SnapShot highlights the transduction ion channels critical to orofacial sensation.
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Affiliation(s)
- Patrick Delmas
- Laboratoire de Neurosciences Cognitives, Aix-Marseille-Université, CNRS, UMR 7291, Marseille, France
| | - Bertrand Coste
- Laboratoire de Neurosciences Cognitives, Aix-Marseille-Université, CNRS, UMR 7291, Marseille, France
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Wu CC, Brugeaud A, Seist R, Lin HC, Yeh WH, Petrillo M, Coppola G, Edge ASB, Stankovic KM. Altered expression of genes regulating inflammation and synaptogenesis during regrowth of afferent neurons to cochlear hair cells. PLoS One 2020; 15:e0238578. [PMID: 33001981 PMCID: PMC7529247 DOI: 10.1371/journal.pone.0238578] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 08/19/2020] [Indexed: 12/20/2022] Open
Abstract
The spiral ganglion neurons constitute the primary connection between auditory hair cells and the brain. The spiral ganglion afferent fibers and their synapse with hair cells do not regenerate to any significant degree in adult mammalian ears after damage. We have investigated gene expression changes after kainate-induced disruption of the synapses in a neonatal cochlear explant model in which peripheral fibers and the afferent synapse do regenerate. We compared gene expression early after damage, during regeneration of the fibers and synapses, and after completion of in vitro regeneration. These analyses revealed a total of 2.5% differentially regulated transcripts (588 out of 24,000) based on a threshold of p<0.005. Inflammatory response genes as well as genes involved in regeneration of neural circuits were upregulated in the spiral ganglion neurons and organ of Corti, where the hair cells reside. Prominent genes upregulated at several time points included genes with roles in neurogenesis (Elavl4 and Sox21), neural outgrowth (Ntrk3 and Ppp1r1c), axonal guidance (Rgmb and Sema7a), synaptogenesis (Nlgn2 and Psd2), and synaptic vesicular function (Syt8 and Syn1). Immunohistochemical and in situ hybridization analysis of genes that had not previously been described in the cochlea confirmed their cochlear expression. The time course of expression of these genes suggests that kainate treatment resulted in a two-phase response in spiral ganglion neurons: an acute response consistent with inflammation, followed by an upregulation of neural regeneration genes. Identification of the genes activated during regeneration of these fibers suggests candidates that could be targeted to enhance regeneration in adult ears.
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Affiliation(s)
- Chen-Chi Wu
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Aurore Brugeaud
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Richard Seist
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Otorhinolaryngology-Head and Neck Surgery, Paracelsus Medical University, Salzburg, Austria
| | - Hsiao-Chun Lin
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Wei-Hsi Yeh
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Marco Petrillo
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Giovanni Coppola
- Program in Neurogenetics, Department of Neurology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Albert S. B. Edge
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (KMS); (ASBE)
| | - Konstantina M. Stankovic
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, Massachusetts, United States of America
- Harvard Program in Therapeutic Science, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (KMS); (ASBE)
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Meerschaert KA, Adelman PC, Friedman RL, Albers KM, Koerber HR, Davis BM. Unique Molecular Characteristics of Visceral Afferents Arising from Different Levels of the Neuraxis: Location of Afferent Somata Predicts Function and Stimulus Detection Modalities. J Neurosci 2020; 40:7216-7228. [PMID: 32817244 PMCID: PMC7534907 DOI: 10.1523/jneurosci.1426-20.2020] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/30/2020] [Accepted: 08/07/2020] [Indexed: 02/07/2023] Open
Abstract
Viscera receive innervation from sensory ganglia located adjacent to multiple levels of the brainstem and spinal cord. Here we examined whether molecular profiling could be used to identify functional clusters of colon afferents from thoracolumbar (TL), lumbosacral (LS), and nodose ganglia (NG) in male and female mice. Profiling of TL and LS bladder afferents was also performed. Visceral afferents were back-labeled using retrograde tracers injected into proximal and distal regions of colon or bladder, followed by single-cell qRT-PCR and analysis via an automated hierarchical clustering method. Genes were chosen for assay (32 for bladder; 48 for colon) based on their established role in stimulus detection, regulation of sensitivity/function, or neuroimmune interaction. A total of 132 colon afferents (from NG, TL, and LS ganglia) and 128 bladder afferents (from TL and LS ganglia) were analyzed. Retrograde labeling from the colon showed that NG and TL afferents innervate proximal and distal regions of the colon, whereas 98% of LS afferents only project to distal regions. There were clusters of colon and bladder afferents, defined by mRNA profiling, that localized to either TL or LS ganglia. Mixed TL/LS clustering also was found. In addition, transcriptionally, NG colon afferents were almost completely segregated from colon TL and LS neurons. Furthermore, colon and bladder afferents expressed genes at similar levels, although different gene combinations defined the clusters. These results indicate that genes implicated in both homeostatic regulation and conscious sensations are found at all anatomic levels, suggesting that afferents from different portions of the neuraxis have overlapping functions.SIGNIFICANCE STATEMENT Visceral organs are innervated by sensory neurons whose cell bodies are located in multiple ganglia associated with the brainstem and spinal cord. For the colon, this overlapping innervation is proposed to facilitate visceral sensation and homeostasis, where sensation and pain are mediated by spinal afferents and fear and anxiety (the affective aspects of visceral pain) are the domain of nodose afferents. The transcriptomic analysis performed here reveals that genes implicated in both homeostatic regulation and pain are found in afferents across all ganglia types, suggesting that conscious sensation and homeostatic regulation are the result of convergence, and not segregation, of sensory input.
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Affiliation(s)
- Kimberly A Meerschaert
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | | | - Robert L Friedman
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Kathryn M Albers
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - H Richard Koerber
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Brian M Davis
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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Barnes JL, Mohr C, Ritchey CR, Erikson CM, Shiina H, Rossi DJ. Developmentally Transient CB1Rs on Cerebellar Afferents Suppress Afferent Input, Downstream Synaptic Excitation, and Signaling to Migrating Neurons. J Neurosci 2020; 40:6133-6145. [PMID: 32631938 PMCID: PMC7406284 DOI: 10.1523/jneurosci.1931-19.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 06/15/2020] [Accepted: 06/20/2020] [Indexed: 01/13/2023] Open
Abstract
The endocannabinoid system plays important roles in brain development, but mechanistic studies have focused on neuronal differentiation, migration, and synaptogenesis, with less attention to transcellular interactions that coordinate neurodevelopmental processes across developing neural networks. We determined that, in the developing rodent cerebellar cortex (of both sexes), there is a transient window when the dominant brain cannabinoid receptor, CB1R, is expressed on afferent terminals instead of output neuron Purkinje cell synapses that dominate the adult cerebellum. Activation of these afferent CB1Rs suppresses synaptic transmission onto developing granule cells, and consequently also suppresses excitation of downstream neurons in the developing cortical network, including nonsynaptic, migrating neurons. Application of a CB1R antagonist during afferent stimulation trains and depolarizing voltage steps caused a significant, sustained potentiation of synaptic amplitude. Our data demonstrate that transiently expressed afferent CB1Rs regulate afferent synaptic strength during synaptogenesis, which enables coordinated dampening of transcortical developmental signals.SIGNIFICANCE STATEMENT The endogenous cannabinoid system plays diverse roles in brain development, which, combined with the rapidly changing legal and medical status of cannabis-related compounds, makes understanding how exogenous cannabinoids affect brain development an important biomedical objective. The cerebellum is a key brain region in a variety of neurodevelopmental disorders, and the adult cerebellum has one of the highest expression levels of CB1R, but little is known about CB1R in the developing cerebellum. Here we report a developmentally distinct expression and function of CB1R in the cerebellum, in which endogenous or exogenous activation of CB1Rs modifies afferent synaptic strength and coordinated downstream network signaling. These findings have implications for recreational and medical use of exogenous cannabinoids by pregnant and breastfeeding women.
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MESH Headings
- Action Potentials
- Animals
- Cannabinoid Receptor Antagonists/pharmacology
- Cell Movement
- Excitatory Postsynaptic Potentials
- Female
- Male
- Mice
- Mice, Inbred C57BL
- Neurogenesis
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Neurons, Afferent/physiology
- Purkinje Cells/drug effects
- Purkinje Cells/metabolism
- Purkinje Cells/physiology
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Synapses/metabolism
- Synapses/physiology
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Affiliation(s)
- Jesse L Barnes
- Washington State University, Integrative Physiology and Neuroscience, Pullman, Washington 99164
| | - Claudia Mohr
- Washington State University, Integrative Physiology and Neuroscience, Pullman, Washington 99164
| | - Caitlin R Ritchey
- Washington State University, Integrative Physiology and Neuroscience, Pullman, Washington 99164
| | - Chloe M Erikson
- Washington State University, Integrative Physiology and Neuroscience, Pullman, Washington 99164
| | - Hiroko Shiina
- Washington State University, Integrative Physiology and Neuroscience, Pullman, Washington 99164
| | - David J Rossi
- Washington State University, Integrative Physiology and Neuroscience, Pullman, Washington 99164
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Harsanyiova J, Ru F, Zatko T, Kollarik M, Hennel M. Vagus Nerves Provide a Robust Afferent Innervation of the Mucosa Throughout the Body of the Esophagus in the Mouse. Dysphagia 2020; 35:471-478. [PMID: 31468191 PMCID: PMC10688604 DOI: 10.1007/s00455-019-10051-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/12/2019] [Indexed: 12/12/2022]
Abstract
The vagal afferent nerves regulate swallowing and esophageal motor reflexes. However, there are still gaps in the understanding of vagal afferent innervation of the esophageal mucosa. Anatomical studies found that the vagal afferent mucosal innervation is dense in the upper esophageal sphincter area but rare in more distal segments of the esophagus. In contrast, electrophysiological studies concluded that the vagal afferent nerve fibers also densely innervate mucosa in more distal esophagus. We hypothesized that the transfection of vagal afferent neurons with adeno-associated virus vector encoding green fluorescent protein (AAV-GFP) allows to visualize vagal afferent nerve fibers in the esophageal mucosa in the mouse. AAV-GFP was injected into the vagal jugular/nodose ganglia in vivo to sparsely label vagal afferent nerve fibers. The esophageal tissue was harvested 4-6 weeks later, the GFP signal was amplified by immunostaining, and confocal optical sections of the entire esophagi were obtained. We found numerous GFP-labeled fibers in the mucosa throughout the whole body of the esophagus. The GFP-labeled mucosal fibers were located just beneath the epithelium, branched repeatedly, had mostly longitudinal orientation, and terminated abruptly without forming terminal structures. The GFP-labeled mucosal fibers were concentrated in random areas of various sizes in which many fibers could be traced to a single parental axon. We conclude that the vagus nerves provide a robust afferent innervation of the mucosa throughout the whole body of the esophagus in the mouse. Vagal mucosal fibers may contribute to the sensing of intraluminal content and regulation of swallowing and other reflexes.
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Affiliation(s)
- J Harsanyiova
- Department of Pathophysiology, Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin (JFM CU), Mala Hora 4C, 036 01, Martin, Slovakia
- Department of Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd, MDC 8, Tampa, FL, 33612, USA
| | - F Ru
- Department of Medicine, Allergy and Asthma Center, The Johns Hopkins University School of Medicine, 5501 Hopkins Bayview Circle, Baltimore, MD, 21224, USA
| | - T Zatko
- Department of Pathophysiology, Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin (JFM CU), Mala Hora 4C, 036 01, Martin, Slovakia
| | - M Kollarik
- Department of Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd, MDC 8, Tampa, FL, 33612, USA
| | - M Hennel
- Division of Neuroscience, Biomedical Center Martin, Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin (JFM CU), Malá Hora 4C, 036 01, Martin, Slovakia.
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Mena-Avila E, Milla-Cruz JJ, Calvo JR, Hochman S, Villalón CM, Arias-Montaño JA, Quevedo JN. Activation of α-adrenoceptors depresses synaptic transmission of myelinated afferents and inhibits pathways mediating primary afferent depolarization (PAD) in the in vitro mouse spinal cord. Exp Brain Res 2020; 238:1293-1303. [PMID: 32322928 PMCID: PMC10751985 DOI: 10.1007/s00221-020-05805-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 04/07/2020] [Indexed: 12/25/2022]
Abstract
Somatosensory afferent transmission strength is controlled by several presynaptic mechanisms that reduce transmitter release at the spinal cord level. We focused this investigation on the role of α-adrenoceptors in modulating sensory transmission in low-threshold myelinated afferents and in pathways mediating primary afferent depolarization (PAD) of neonatal mouse spinal cord. We hypothesized that the activation of α-adrenoceptors depresses low threshold-evoked synaptic transmission and inhibits pathways mediating PAD. Extracellular field potentials (EFPs) recorded in the deep dorsal horn assessed adrenergic modulation of population monosynaptic transmission, while dorsal root potentials (DRPs) recorded at root entry zone assessed adrenergic modulation of PAD. We found that noradrenaline (NA) and the α1-adrenoceptor agonists phenylephrine and cirazoline depressed synaptic transmission (by 15, 14 and 22%, respectively). DRPs were also depressed by NA, phenylephrine and cirazoline (by 62, 30, and 64%, respectively), and by the α2-adrenoceptor agonist clonidine, although to a lower extent (20%). We conclude that NA depresses monosynaptic transmission of myelinated afferents onto deep dorsal horn neurons via α1-adrenoceptors and inhibits interneuronal pathways mediating PAD through the activation of α1- and α2-adrenoceptors. The functional significance of these modulatory actions in shaping cutaneous and muscle sensory information during motor behaviors requires further study.
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MESH Headings
- Adrenergic alpha-Agonists/pharmacology
- Animals
- Animals, Newborn
- Electrophysiological Phenomena/drug effects
- Electrophysiological Phenomena/physiology
- In Vitro Techniques
- Mice
- Mice, Inbred BALB C
- Nerve Fibers, Myelinated/physiology
- Neural Pathways/physiology
- Neurons, Afferent/physiology
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/physiology
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/physiology
- Spinal Cord Dorsal Horn/physiology
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
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Affiliation(s)
- Elvia Mena-Avila
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Cinvestav del IPN, Av. IPN 2508, San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - Jonathan J Milla-Cruz
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Cinvestav del IPN, Av. IPN 2508, San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - Jorge R Calvo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Cinvestav del IPN, Av. IPN 2508, San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - Shawn Hochman
- Physiology Department, Emory University, Atlanta, GA, USA
| | - Carlos M Villalón
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Sede-Sur, Ciudad de México, Mexico
| | - José-Antonio Arias-Montaño
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Cinvestav del IPN, Av. IPN 2508, San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - Jorge N Quevedo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Cinvestav del IPN, Av. IPN 2508, San Pedro Zacatenco, 07360, Ciudad de México, Mexico.
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48
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Affiliation(s)
- Horacio Kaufmann
- From the Department of Neurology, Dysautonomia Center, New York University School of Medicine, New York
| | - Lucy Norcliffe-Kaufmann
- From the Department of Neurology, Dysautonomia Center, New York University School of Medicine, New York
| | - Jose-Alberto Palma
- From the Department of Neurology, Dysautonomia Center, New York University School of Medicine, New York
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49
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Abstract
Galanin is a neuropeptide expressed by sensory neurones innervating the gastrointestinal (GI) tract. Galanin displays inhibitory effects on vagal afferent signaling within the upper GI tract, and the goal of this study was to determine the actions of galanin on colonic spinal afferent function. Specifically, we sought to evaluate the effect of galanin on lumbar splanchnic nerve (LSN) mechanosensitivity to noxious distending pressures and the development of hypersensitivity in the presence of inflammatory stimuli and colitis. Using ex vivo electrophysiological recordings we show that galanin produces a dose-dependent suppression of colonic LSN responses to mechanical stimuli and prevents the development of hypersensitivity to acutely administered inflammatory mediators. Using galanin receptor (GalR) agonists, we show that GalR1 activation, but not GalR2/3 activation, suppresses mechanosensitivity. The effect of galanin on colonic afferent activity was not observed in tissue from mice with dextran sodium sulfate-induced colitis. We conclude that galanin has a marked suppressive effect on colonic mechanosensitivity at noxious distending pressures and prevents the acute development of mechanical hypersensitivity to inflammatory mediators, an effect not seen in the inflamed colon. These actions highlight a potential role for galanin in the regulation of mechanical nociception in the bowel and the therapeutic potential of targeting galaninergic signaling to treat visceral hypersensitivity.
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Affiliation(s)
- Toni S. Taylor
- Department of PharmacologyUniversity of CambridgeCambridgeUK
| | - Parvesh Konda
- Department of PharmacologyUniversity of CambridgeCambridgeUK
| | - Sarah S. John
- Department of PharmacologyUniversity of CambridgeCambridgeUK
| | - David C. Bulmer
- Department of PharmacologyUniversity of CambridgeCambridgeUK
| | - James R. F. Hockley
- Department of PharmacologyUniversity of CambridgeCambridgeUK
- GSKGSK Medicines Research CentreStevenageHertfordshireUK
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50
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Abstract
To provide a meaningful representation of the auditory landscape, mammalian cochlear hair cells are optimized to detect sounds over an incredibly broad range of frequencies and intensities with unparalleled accuracy. This ability is largely conferred by specialized ribbon synapses that continuously transmit acoustic information with high fidelity and sub-millisecond precision to the afferent dendrites of the spiral ganglion neurons. To achieve this extraordinary task, ribbon synapses employ a unique combination of molecules and mechanisms that are tailored to sounds of different frequencies. Here we review the current understanding of how the hair cell's presynaptic machinery and its postsynaptic afferent connections are formed, how they mature, and how their function is adapted for an accurate perception of sound.
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Affiliation(s)
- Stuart L Johnson
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Saaid Safieddine
- UMRS 1120, Institut Pasteur, Paris, France
- Sorbonne Universités, UPMC Université Paris 06, Complexité du Vivant, Paris, France
| | - Mirna Mustapha
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
- Department of Otolaryngology-Head & Neck Surgery, Stanford University, Stanford, California 94035
| | - Walter Marcotti
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
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