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Harbour K, Baccei ML. Influence of Early-Life Stress on the Excitability of Dynorphin Neurons in the Adult Mouse Dorsal Horn. THE JOURNAL OF PAIN 2024:104609. [PMID: 38885917 DOI: 10.1016/j.jpain.2024.104609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 05/24/2024] [Accepted: 06/11/2024] [Indexed: 06/20/2024]
Abstract
While early-life adversity has been associated with a higher risk of developing chronic pain in adulthood, the cellular and molecular mechanisms by which chronic stress during the neonatal period can persistently sensitize developing nociceptive circuits remain poorly understood. Here, we investigate the effects of early-life stress (ELS) on synaptic integration and intrinsic excitability in dynorphin-lineage (DYN) interneurons within the adult mouse superficial dorsal horn (SDH), which are important for inhibiting mechanical pain and itch. The administration of neonatal limited bedding between postnatal days (P)2 and P9 evoked sex-dependent effects on spontaneous glutamatergic signaling, as female SDH neurons exhibited a higher amplitude of miniature excitatory postsynaptic currents (mEPSCs) after ELS, while mEPSC frequency was reduced in DYN neurons of the male SDH. Furthermore, ELS decreased the frequency of miniature inhibitory postsynaptic currents selectively in female DYN neurons. As a result, ELS increased the balance of spontaneous excitation versus inhibition (E:I ratio) in mature DYN neurons of the female, but not male, SDH network. Nonetheless, ELS weakened the total primary afferent-evoked glutamatergic drive onto adult DYN neurons selectively in females, without modifying afferent-evoked inhibitory signaling onto the DYN population. Finally, ELS failed to significantly change the intrinsic membrane excitability of mature DYN neurons in either males or females. Collectively, these data suggest that ELS exerts a long-term influence on the properties of synaptic transmission onto DYN neurons within the adult SDH, which includes a reduction in the overall strength of sensory input onto this important subset of inhibitory interneurons. PERSPECTIVE: This study suggests that chronic stress during the neonatal period influences synaptic function within adult spinal nociceptive circuits in a sex-dependent manner. These findings yield new insight into the potential mechanisms by which early-life adversity might shape the maturation of pain pathways in the central nervous system (CNS).
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Affiliation(s)
- Kyle Harbour
- Molecular, Cellular and Biochemical Pharmacology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, Ohio; Department of Anesthesiology, Pain Research Center, University of Cincinnati Medical Center, Cincinnati, Ohio
| | - Mark L Baccei
- Molecular, Cellular and Biochemical Pharmacology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, Ohio; Department of Anesthesiology, Pain Research Center, University of Cincinnati Medical Center, Cincinnati, Ohio.
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2
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Upadhyay A, Gradwell MA, Vajtay TJ, Conner J, Sanyal AA, Azadegan C, Patel KR, Thackray JK, Bohic M, Imai F, Ogundare SO, Yoshida Y, Abdus-Saboor I, Azim E, Abraira VE. The Dorsal Column Nuclei Scale Mechanical Sensitivity in Naive and Neuropathic Pain States. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.20.581208. [PMID: 38712022 PMCID: PMC11071288 DOI: 10.1101/2024.02.20.581208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Tactile perception relies on reliable transmission and modulation of low-threshold information as it travels from the periphery to the brain. During pathological conditions, tactile stimuli can aberrantly engage nociceptive pathways leading to the perception of touch as pain, known as mechanical allodynia. Two main drivers of peripheral tactile information, low-threshold mechanoreceptors (LTMRs) and postsynaptic dorsal column neurons (PSDCs), terminate in the brainstem dorsal column nuclei (DCN). Activity within the DRG, spinal cord, and DCN have all been implicated in mediating allodynia, yet the DCN remains understudied at the cellular, circuit, and functional levels compared to the other two. Here, we show that the gracile nucleus (Gr) of the DCN mediates tactile sensitivity for low-threshold stimuli and contributes to mechanical allodynia during neuropathic pain in mice. We found that the Gr contains local inhibitory interneurons in addition to thalamus-projecting neurons, which are differentially innervated by primary afferents and spinal inputs. Functional manipulations of these distinct Gr neuronal populations resulted in bidirectional changes to tactile sensitivity, but did not affect noxious mechanical or thermal sensitivity. During neuropathic pain, silencing Gr projection neurons or activating Gr inhibitory neurons was able to reduce tactile hypersensitivity, and enhancing inhibition was able to ameliorate paw withdrawal signatures of neuropathic pain, like shaking. Collectively, these results suggest that the Gr plays a specific role in mediating hypersensitivity to low-threshold, innocuous mechanical stimuli during neuropathic pain, and that Gr activity contributes to affective, pain-associated phenotypes of mechanical allodynia. Therefore, these brainstem circuits work in tandem with traditional spinal circuits underlying allodynia, resulting in enhanced signaling of tactile stimuli in the brain during neuropathic pain.
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Affiliation(s)
- Aman Upadhyay
- W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA; Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA
- Brain Health Institute, Rutgers University, Piscataway, New Jersey, USA
- Neuroscience PhD program at Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | - Mark A Gradwell
- W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA; Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA
- Brain Health Institute, Rutgers University, Piscataway, New Jersey, USA
| | - Thomas J Vajtay
- W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA; Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - James Conner
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Arnab A Sanyal
- W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA; Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Chloe Azadegan
- W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA; Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Komal R Patel
- W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA; Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Joshua K Thackray
- Human Genetics Institute of New Jersey, Rutgers University, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Manon Bohic
- W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA; Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA
- Brain Health Institute, Rutgers University, Piscataway, New Jersey, USA
| | - Fumiyasu Imai
- Burke Neurological Institute, White Plains, New York City, New York, USA
- Brain and Mind Research Institute, Weill Cornell Medicine, New York City, New York, USA
| | - Simon O Ogundare
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA; Department of Biological Sciences, Columbia University, New York City, New York, USA
| | - Yutaka Yoshida
- Burke Neurological Institute, White Plains, New York City, New York, USA
- Brain and Mind Research Institute, Weill Cornell Medicine, New York City, New York, USA
| | - Ishmail Abdus-Saboor
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA; Department of Biological Sciences, Columbia University, New York City, New York, USA
| | - Eiman Azim
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Victoria E Abraira
- W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA; Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey, USA
- Brain Health Institute, Rutgers University, Piscataway, New Jersey, USA
- Lead contact
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3
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Espinosa F, Pop IV, Lai HC. Electrophysiological Properties of Proprioception-Related Neurons in the Intermediate Thoracolumbar Spinal Cord. eNeuro 2024; 11:ENEURO.0331-23.2024. [PMID: 38627062 PMCID: PMC11055654 DOI: 10.1523/eneuro.0331-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 04/03/2024] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
Proprioception, the sense of limb and body position, is required to produce accurate and precise movements. Proprioceptive sensory neurons transmit muscle length and tension information to the spinal cord. The function of excitatory neurons in the intermediate spinal cord, which receive this proprioceptive information, remains poorly understood. Using genetic labeling strategies and patch-clamp techniques in acute spinal cord preparations in mice, we set out to uncover how two sets of spinal neurons, Clarke's column (CC) and Atoh1-lineage neurons, respond to electrical activity and how their inputs are organized. Both sets of neurons are located in close proximity in laminae V-VII of the thoracolumbar spinal cord and have been described to receive proprioceptive signals. We find that a majority of CC neurons have a tonic-firing type and express a distinctive hyperpolarization-activated current (Ih). Atoh1-lineage neurons, which cluster into two spatially distinct populations, are mostly a fading-firing type and display similar electrophysiological properties to each other, possibly due to their common developmental lineage. Finally, we find that CC neurons respond to stimulation of lumbar dorsal roots, consistent with prior knowledge that CC neurons receive hindlimb proprioceptive information. In contrast, using a combination of electrical stimulation, optogenetic stimulation, and transsynaptic rabies virus tracing, we find that Atoh1-lineage neurons receive heterogeneous, predominantly local thoracic inputs that include parvalbumin-lineage sensory afferents and local interneuron presynaptic inputs. Altogether, we find that CC and Atoh1-lineage neurons have distinct membrane properties and sensory input organization, representing different subcircuit modes of proprioceptive information processing.
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Affiliation(s)
- Felipe Espinosa
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, Texas 75390
| | - Iliodora V Pop
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, Texas 75390
| | - Helen C Lai
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, Texas 75390
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Safronov BV, Szucs P. Novel aspects of signal processing in lamina I. Neuropharmacology 2024; 247:109858. [PMID: 38286189 DOI: 10.1016/j.neuropharm.2024.109858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/12/2024] [Accepted: 01/25/2024] [Indexed: 01/31/2024]
Abstract
The most superficial layer of the spinal dorsal horn, lamina I, is a key element of the nociceptive processing system. It contains different types of projection neurons (PNs) and local-circuit neurons (LCNs) whose functional roles in the signal processing are poorly understood. This article reviews recent progress in elucidating novel anatomical features and physiological properties of lamina I PNs and LCNs revealed by whole-cell recordings in ex vivo spinal cord. This article is part of the Special Issue on "Ukrainian Neuroscience".
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Affiliation(s)
- Boris V Safronov
- Neuronal Networks Group, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
| | - Peter Szucs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; HUN-REN-DE Neuroscience Research Group, Debrecen, Hungary
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5
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Eliav T, Benoliel R, Korczeniewska OA. Post-Traumatic Trigeminal Neuropathy: Neurobiology and Pathophysiology. BIOLOGY 2024; 13:167. [PMID: 38534437 DOI: 10.3390/biology13030167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/23/2024] [Accepted: 02/26/2024] [Indexed: 03/28/2024]
Abstract
Painful traumatic trigeminal neuropathy (PTTN) is a chronic neuropathic pain that may develop following injury to the trigeminal nerve. Etiologies include cranio-orofacial trauma that may result from dental, surgical, or anesthetic procedures or physical trauma, such as a motor vehicle accident. Following nerve injury, there are various mechanisms, including peripheral and central, as well as phenotypic changes and genetic predispositions that may contribute to the development of neuropathic pain. In this article, we review current literature pertaining to the cellular processes that occur following traumatic damage to the trigeminal nerve, also called cranial nerve V, that results in chronic neuropathic pain. We examine the neurobiology and pathophysiology based mostly on pre-clinical animal models of neuropathic/trigeminal pain.
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Affiliation(s)
- Tal Eliav
- Medical School for International Health, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 8410501, Israel
| | - Rafael Benoliel
- Center for Orofacial Pain and Temporomandibular Disorders, Department of Diagnostic Sciences, Rutgers School of Dental Medicine, Rutgers, The State University of New Jersey, Room D-837, 110 Bergen Street, Newark, NJ 07101, USA
| | - Olga A Korczeniewska
- Center for Orofacial Pain and Temporomandibular Disorders, Department of Diagnostic Sciences, Rutgers School of Dental Medicine, Rutgers, The State University of New Jersey, Room D-837, 110 Bergen Street, Newark, NJ 07101, USA
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6
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Rankin G, Chirila AM, Emanuel AJ, Zhang Z, Woolf CJ, Drugowitsch J, Ginty DD. Nerve injury disrupts temporal processing in the spinal cord dorsal horn through alterations in PV + interneurons. Cell Rep 2024; 43:113718. [PMID: 38294904 PMCID: PMC11101906 DOI: 10.1016/j.celrep.2024.113718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 11/13/2023] [Accepted: 01/11/2024] [Indexed: 02/02/2024] Open
Abstract
How mechanical allodynia following nerve injury is encoded in patterns of neural activity in the spinal cord dorsal horn (DH) remains incompletely understood. We address this in mice using the spared nerve injury model of neuropathic pain and in vivo electrophysiological recordings. Surprisingly, despite dramatic behavioral over-reactivity to mechanical stimuli following nerve injury, an overall increase in sensitivity or reactivity of DH neurons is not observed. We do, however, observe a marked decrease in correlated neural firing patterns, including the synchrony of mechanical stimulus-evoked firing, across the DH. Alterations in DH temporal firing patterns are recapitulated by silencing DH parvalbumin+ (PV+) interneurons, previously implicated in mechanical allodynia, as are allodynic pain-like behaviors. These findings reveal decorrelated DH network activity, driven by alterations in PV+ interneurons, as a prominent feature of neuropathic pain and suggest restoration of proper temporal activity as a potential therapeutic strategy to treat chronic neuropathic pain.
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Affiliation(s)
- Genelle Rankin
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Anda M Chirila
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Alan J Emanuel
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Zihe Zhang
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Clifford J Woolf
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jan Drugowitsch
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - David D Ginty
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA.
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7
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Chen X, Tang SJ. Neural Circuitry Polarization in the Spinal Dorsal Horn (SDH): A Novel Form of Dysregulated Circuitry Plasticity during Pain Pathogenesis. Cells 2024; 13:398. [PMID: 38474361 PMCID: PMC10930392 DOI: 10.3390/cells13050398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 02/20/2024] [Accepted: 02/23/2024] [Indexed: 03/14/2024] Open
Abstract
Pathological pain emerges from nociceptive system dysfunction, resulting in heightened pain circuit activity. Various forms of circuitry plasticity, such as central sensitization, synaptic plasticity, homeostatic plasticity, and excitation/inhibition balance, contribute to the malfunction of neural circuits during pain pathogenesis. Recently, a new form of plasticity in the spinal dorsal horn (SDH), named neural circuit polarization (NCP), was discovered in pain models induced by HIV-1 gp120 and chronic morphine administration. NCP manifests as an increase in excitatory postsynaptic currents (EPSCs) in excitatory neurons and a decrease in EPSCs in inhibitory neurons, presumably facilitating hyperactivation of pain circuits. The expression of NCP is associated with astrogliosis. Ablation of reactive astrocytes or suppression of astrogliosis blocks NCP and, concomitantly, the development of gp120- or morphine-induced pain. In this review, we aim to compare and integrate NCP with other forms of plasticity in pain circuits to improve the understanding of the pathogenic contribution of NCP and its cooperation with other forms of circuitry plasticity during the development of pathological pain.
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Affiliation(s)
| | - Shao-Jun Tang
- Stony Brook University Pain and Anesthesia Research Center (SPARC), Department of Anesthesiology, Stony Brook University, Stony Brook, NY 11794, USA;
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8
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Bai HH, Wang KL, Zeng XR, Li J, Li Y, Xu JY, Zhang Y, Jiang HF, Yang X, Suo ZW, Hu XD. GPR39 regulated spinal glycinergic inhibition and mechanical inflammatory pain. SCIENCE ADVANCES 2024; 10:eadj3808. [PMID: 38306424 PMCID: PMC10836721 DOI: 10.1126/sciadv.adj3808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 01/04/2024] [Indexed: 02/04/2024]
Abstract
G protein-coupled receptor 39 (GPR39) senses the change of extracellular divalent zinc ion and signals through multiple G proteins to a broad spectrum of downstream effectors. Here, we found that GPR39 was prevalent at inhibitory synapses of spinal cord somatostatin-positive (SOM+) interneurons, a mechanosensitive subpopulation that is critical for the conveyance of mechanical pain. GPR39 complexed specifically with inhibitory glycine receptors (GlyRs) and helped maintain glycinergic transmission in a manner independent of G protein signalings. Targeted knockdown of GPR39 in SOM+ interneurons reduced the glycinergic inhibition and facilitated the excitatory output from SOM+ interneurons to spinoparabrachial neurons that engaged superspinal neural circuits encoding both the sensory discriminative and affective motivational domains of pain experience. Our data showed that pharmacological activation of GPR39 or augmenting GPR39 interaction with GlyRs at the spinal level effectively alleviated the sensory and affective pain induced by complete Freund's adjuvant and implicated GPR39 as a promising therapeutic target for the treatment of inflammatory mechanical pain.
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Affiliation(s)
- Hu-Hu Bai
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
- School of Life Science, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Kang-Li Wang
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Xiang-Ru Zeng
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Jing Li
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Yuan Li
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Jia-Yu Xu
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Yue Zhang
- School of Public Health, Gansu University of Chinese medicine, Lanzhou, Gansu 730000, P.R. China
| | - Hai-Feng Jiang
- School of Public Health, Gansu University of Chinese medicine, Lanzhou, Gansu 730000, P.R. China
| | - Xian Yang
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Zhan-Wei Suo
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Xiao-Dong Hu
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
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9
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Fujiwara Y, Koga K, Nakamura NH, Maruo K, Tachibana T, Furue H. Optogenetic inhibition of spinal inhibitory neurons facilitates mechanical responses of spinal wide dynamic range neurons and causes mechanical hypersensitivity. Neuropharmacology 2024; 242:109763. [PMID: 37852319 DOI: 10.1016/j.neuropharm.2023.109763] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/06/2023] [Accepted: 10/14/2023] [Indexed: 10/20/2023]
Abstract
Inhibitory interneurons in the spinal dorsal horn (DH) play a major role in regulating innocuous and noxious information. Reduction in inhibitory synaptic transmission is thought to contribute to the development of touch-evoked pain (allodynia), a common symptom of neuropathic pain. However, it is not fully understood how inhibitory neurons in the DH regulate sensory responses in surrounding neurons and modulate sensory transmission. In this study, we established a novel experimental method to analyze temporal activity of DH neurons during the optogenetically induced disinhibition state by combining extracellular recording and optogenetics. We investigated how specific and temporally restricted dysfunction of DH inhibitory neurons affected spinal neuronal activities evoked by cutaneous mechanical stimulation. In behavioral experiments, the specific and temporally restricted spinal optogenetic suppression of DH inhibitory neurons induced mechanical hypersensitivity. Furthermore, this manipulation enhanced the mechanical responses of wide dynamic range (WDR) neurons, which are important for pain transmission, in response to brush and von Frey stimulation but not in response to nociceptive pinch stimulation. In addition, we examined whether a neuropathic pain medication, mirogabalin, suppressed these optogenetically induced abnormal pain responses. We found that mirogabalin treatment attenuated the abnormal firing responses of WDR neurons and mechanical hypersensitivity. These results suggest that temporally restricted and specific reduction of spinal inhibitory neuronal activity facilitates the mechanical responses of WDR neurons, resulting in neuropathic-like mechanical allodynia which can be suppressed by mirogabalin. Our optogenetic methods could be useful for developing novel therapeutics for neuropathic pain.
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Affiliation(s)
- Yuka Fujiwara
- Department of Neurophysiology, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan; Department of Orthopaedic Surgery, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan
| | - Keisuke Koga
- Department of Neurophysiology, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan.
| | - Nozomu H Nakamura
- Department of Physiology, Hyogo Medical University, 1-1, Mukogawa, Nishinomiya, 663-8501, Japan
| | - Keishi Maruo
- Department of Orthopaedic Surgery, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan
| | - Toshiya Tachibana
- Department of Orthopaedic Surgery, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan.
| | - Hidemasa Furue
- Department of Neurophysiology, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan
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10
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Moreau N, Peirs C, Dallel R, Boucher Y. [Specificities of orofacial neuropathic pain]. Med Sci (Paris) 2024; 40:64-71. [PMID: 38299905 DOI: 10.1051/medsci/2023197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2024] Open
Abstract
Head pain and notably orofacial pain differs from spinal pain on pathophysiological, clinical, therapeutic and prognostic levels. Its high prevalence, important impact on quality of life and significant socio-economical burden justify specific study of such type of pain. Among them, neuropathic orofacial pain resulting from disease or trauma of the trigeminal nervous system is among the most difficult types of pain to diagnose and to treat. Deciphering of underlying peripheral and central mechanisms has allowed numerous conceptual, clinical and therapeutic advances, notably the role of neural and non neural cell types, such as glia, immunocytes, vascular endothelial cells or the role of trigeminal sensory complex neural circuitry reconfiguration in the development of post-traumatic trigeminal neuropathic pain. Cellular interactions within the trigeminal ganglion, allowing a better understanding of several painful dental, ocular or cephalalgic comorbidities, are also described.
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Affiliation(s)
- Nathan Moreau
- Laboratoire de neurobiologie orofaciale, EA 7543, Université Paris Cité, Paris, France - Hôpital Bretonneau, Service de médecine bucco-dentaire, AP-HP, Paris, France
| | - Cédric Peirs
- Université Clermont Auvergne, CHU Clermont-Ferrand, Inserm, Neuro-Dol, Clermont-Ferrand, France
| | - Radhouane Dallel
- Université Clermont Auvergne, CHU Clermont-Ferrand, Inserm, Neuro-Dol, Clermont-Ferrand, France
| | - Yves Boucher
- Laboratoire de neurobiologie orofaciale, EA 7543, Université Paris Cité, Paris, France - Hôpital Pitié-Salpêtrière, Service de médecine bucco-dentaire, AP-HP, Paris, France
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11
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Blažetić S, Krajina V, Labak I, Viljetić B, Pavić V, Ivić V, Balog M, Schnaar RL, Heffer M. Sialyltransferase Mutations Alter the Expression of Calcium-Binding Interneurons in Mice Neocortex, Hippocampus and Striatum. Int J Mol Sci 2023; 24:17218. [PMID: 38139047 PMCID: PMC10743413 DOI: 10.3390/ijms242417218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 11/30/2023] [Accepted: 12/04/2023] [Indexed: 12/24/2023] Open
Abstract
Gangliosides are major glycans on vertebrate nerve cells, and their metabolic disruption results in congenital disorders with marked cognitive and motor deficits. The sialyltransferase gene St3gal2 is responsible for terminal sialylation of two prominent brain gangliosides in mammals, GD1a and GT1b. In this study, we analyzed the expression of calcium-binding interneurons in primary sensory (somatic, visual, and auditory) and motor areas of the neocortex, hippocampus, and striatum of St3gal2-null mice as well as St3gal3-null and St3gal2/3-double null. Immunohistochemistry with highly specific primary antibodies for GABA, parvalbumin, calretinin, and calbindin were used for interneuron detection. St3gal2-null mice had decreased expression of all three analyzed types of calcium-binding interneurons in all analyzed regions of the neocortex. These results implicate gangliosides GD1a and GT1b in the process of interneuron migration and maturation.
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Affiliation(s)
- Senka Blažetić
- Department of Biology, Josip Juraj Strossmayer University of Osijek, Ulica cara Hadrijana 8A, 31000 Osijek, Croatia; (S.B.); (V.P.)
| | - Vinko Krajina
- Department of Medical Biology, School of Medicine, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia; (V.K.); (V.I.); (M.B.); (M.H.)
| | - Irena Labak
- Department of Biology, Josip Juraj Strossmayer University of Osijek, Ulica cara Hadrijana 8A, 31000 Osijek, Croatia; (S.B.); (V.P.)
| | - Barbara Viljetić
- Department of Chemistry, Biochemistry and Clinical Chemistry, School of Medicine, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia;
| | - Valentina Pavić
- Department of Biology, Josip Juraj Strossmayer University of Osijek, Ulica cara Hadrijana 8A, 31000 Osijek, Croatia; (S.B.); (V.P.)
| | - Vedrana Ivić
- Department of Medical Biology, School of Medicine, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia; (V.K.); (V.I.); (M.B.); (M.H.)
| | - Marta Balog
- Department of Medical Biology, School of Medicine, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia; (V.K.); (V.I.); (M.B.); (M.H.)
| | - Ronald L. Schnaar
- Department of Pharmacology and Neuroscience, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA;
| | - Marija Heffer
- Department of Medical Biology, School of Medicine, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia; (V.K.); (V.I.); (M.B.); (M.H.)
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12
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Gilbert JE, Zhang T, Esteller R, Grill WM. Network model of nociceptive processing in the superficial spinal dorsal horn reveals mechanisms of hyperalgesia, allodynia, and spinal cord stimulation. J Neurophysiol 2023; 130:1103-1117. [PMID: 37727912 DOI: 10.1152/jn.00186.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 09/13/2023] [Accepted: 09/15/2023] [Indexed: 09/21/2023] Open
Abstract
The spinal dorsal horn (DH) processes sensory information and plays a key role in transmitting nociception to supraspinal centers. Loss of DH inhibition during neuropathic pain unmasks a pathway from nonnociceptive Aβ-afferent inputs to superficial dorsal horn (SDH) nociceptive-specific (NS) projection neurons, and this change may contribute to hyperalgesia and allodynia. We developed and validated a computational model of SDH neuronal circuitry that links nonnociceptive Aβ-afferent inputs in lamina II/III to a NS projection neuron in lamina I via a network of excitatory interneurons. The excitatory pathway and the NS projection neuron were in turn gated by inhibitory interneurons with connections based on prior patch-clamp recordings. Changing synaptic weights in the computational model to replicate neuropathic pain states unmasked a low-threshold excitatory pathway to NS neurons similar to experimental recordings. Spinal cord stimulation (SCS) is an effective therapy for neuropathic pain, and accumulating experimental evidence indicates that NS neurons in the SDH also respond to SCS. Accounting for these responses may inform therapeutic improvements, and we quantified responses to SCS in the SDH network model and examined the role of different modes of inhibitory control in modulating NS neuron responses to SCS. We combined the SDH network model with a previously published model of the deep dorsal horn (DDH) and identified optimal stimulation frequencies across different neuropathic pain conditions. Finally, we found that SCS-generated inhibition did not completely suppress model NS activity during simulated pinch inputs, providing an explanation of why SCS does not eliminate acute pain.NEW & NOTEWORTHY Chronic pain is a severe public health problem that reduces the quality of life for those affected and exacts an enormous socio-economic burden worldwide. Spinal cord stimulation (SCS) is an effective treatment for chronic pain, but SCS efficacy has not significantly improved over time, in part because the mechanisms of action remain unclear. Most preclinical studies investigating pain and SCS mechanisms have focused on the responses of deep dorsal horn (DDH) neurons, but neural networks in the superficial dorsal horn (SDH) are also important for processing nociceptive information. This work synthesizes heterogeneous experimental recordings from the SDH into a computational model that replicates experimental responses and that can be used to quantify neuronal responses to SCS under neuropathic pain conditions.
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Affiliation(s)
- John E Gilbert
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| | - Tianhe Zhang
- Neuromodulation Research and Advanced Concepts, Boston Scientific Neuromodulation, Valencia, California, United States
| | - Rosana Esteller
- Neuromodulation Research and Advanced Concepts, Boston Scientific Neuromodulation, Valencia, California, United States
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
- Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, United States
- Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina, United States
- Department of Neurosurgery, Duke University School of Medicine, Durham, North Carolina, United States
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13
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Guo R, Xue J, Shao P, Cai C, Wang Y. NETO2-GluK2 interaction contributes to postoperative pain hypersensitivity through inducing PKCγ activation and synaptic incorporation of AMPA receptor GluR1 subunits in rat dorsal horn. Neurosci Lett 2023; 813:137430. [PMID: 37544581 DOI: 10.1016/j.neulet.2023.137430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 08/02/2023] [Accepted: 08/03/2023] [Indexed: 08/08/2023]
Abstract
Important roles in the initiation and maintenance of postoperative pain are played by the functional control of kainate (KA) and α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors in the rat dorsal horn (DH). However, the mechanisms underpinning the cross-talk between spinal KA and AMPA receptors in postoperative pain are poorly understood. We hypothesized that after the rat's plantar incision, the synaptic incorporation of AMPA receptor GluR1 subunits in the DH ipsilateral to the incision would increase due to the interaction between GluK2 and neuropilin tolloid-like 2 (NETO2). Our findings showed that incision stimuli caused severe pain responses, as measured by cumulative pain scores. GluK2-NETO2 but not GluK2-NETO1interaction was upregulated in ipsilateral dorsal horn neurons (DHNs) at 6 h post-incision. At 6 h post-incision, NETO2 small interfering ribonucleic acid (siRNA) intrathecal pretreatment increased mechanical withdrawal thresholds to von Freys and decreased ipsilateral paw cumulative pain scores. Further, PKCγactivation and synaptic abundance of GluK2 and GluR1 subunits in the ipsilateral DH were decreased by intrathecal pretreatment with NETO2 siRNA at 6 h post-incision. In conclusion, our findings imply that GluK2-NETO2 interaction could trigger PKCγactivation and the synaptic incorporation of AMPA receptor GluR1 subunits in rat DHs, which in turn led to the enhanced pain hypersensitivity after surgery. It sheds light on the interplay between KA and AMPA receptors in DHNs, which is thought to contribute to postoperative pain.
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Affiliation(s)
- Ruijuan Guo
- Department of Anesthesiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Jianjun Xue
- Department of Anesthesiology, Gansu Provincial Hospital of Traditional Chinese Medicine, Lanzhou 730050, Gansu, China
| | - Peiqi Shao
- Department of Anesthesiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China
| | - Chenghui Cai
- Department of Anesthesiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China
| | - Yun Wang
- Department of Anesthesiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
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14
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Du F, Yin G, Han L, Liu X, Dong D, Duan K, Huo J, Sun Y, Cheng L. Targeting Peripheral μ-opioid Receptors or μ-opioid Receptor-Expressing Neurons Does not Prevent Morphine-induced Mechanical Allodynia and Anti-allodynic Tolerance. Neurosci Bull 2023; 39:1210-1228. [PMID: 36622575 PMCID: PMC10387027 DOI: 10.1007/s12264-022-01009-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 09/19/2022] [Indexed: 01/10/2023] Open
Abstract
The chronic use of morphine and other opioids is associated with opioid-induced hypersensitivity (OIH) and analgesic tolerance. Among the different forms of OIH and tolerance, the opioid receptors and cell types mediating opioid-induced mechanical allodynia and anti-allodynic tolerance remain unresolved. Here we demonstrated that the loss of peripheral μ-opioid receptors (MORs) or MOR-expressing neurons attenuated thermal tolerance, but did not affect the expression and maintenance of morphine-induced mechanical allodynia and anti-allodynic tolerance. To confirm this result, we made dorsal root ganglia-dorsal roots-sagittal spinal cord slice preparations and recorded low-threshold Aβ-fiber stimulation-evoked inputs and outputs in superficial dorsal horn neurons. Consistent with the behavioral results, peripheral MOR loss did not prevent the opening of Aβ mechanical allodynia pathways in the spinal dorsal horn. Therefore, the peripheral MOR signaling pathway may not be an optimal target for preventing mechanical OIH and analgesic tolerance. Future studies should focus more on central mechanisms.
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Affiliation(s)
- Feng Du
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, 150001, China
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Guangjuan Yin
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Lei Han
- Department of Anesthesiology, Shenzhen University General Hospital, Shenzhen University, Shenzhen, 518055, China
| | - Xi Liu
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Dong Dong
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Kaifang Duan
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Jiantao Huo
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Yanyan Sun
- Department of Anesthesiology, Shenzhen University General Hospital, Shenzhen University, Shenzhen, 518055, China.
| | - Longzhen Cheng
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China.
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China.
- Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China.
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15
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Ma Q, Su D, Huo J, Yin G, Dong D, Duan K, Cheng H, Xu H, Ma J, Liu D, Mou B, Peng J, Cheng L. Microglial Depletion does not Affect the Laterality of Mechanical Allodynia in Mice. Neurosci Bull 2023; 39:1229-1245. [PMID: 36637789 PMCID: PMC10387012 DOI: 10.1007/s12264-022-01017-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 10/12/2022] [Indexed: 01/14/2023] Open
Abstract
Mechanical allodynia (MA), including punctate and dynamic forms, is a common and debilitating symptom suffered by millions of chronic pain patients. Some peripheral injuries result in the development of bilateral MA, while most injuries usually led to unilateral MA. To date, the control of such laterality remains poorly understood. Here, to study the role of microglia in the control of MA laterality, we used genetic strategies to deplete microglia and tested both dynamic and punctate forms of MA in mice. Surprisingly, the depletion of central microglia did not prevent the induction of bilateral dynamic and punctate MA. Moreover, in dorsal root ganglion-dorsal root-sagittal spinal cord slice preparations we recorded the low-threshold Aβ-fiber stimulation-evoked inputs and outputs of superficial dorsal horn neurons. Consistent with behavioral results, microglial depletion did not prevent the opening of bilateral gates for Aβ pathways in the superficial dorsal horn. This study challenges the role of microglia in the control of MA laterality in mice. Future studies are needed to further understand whether the role of microglia in the control of MA laterality is etiology-or species-specific.
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Affiliation(s)
- Quan Ma
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, 150001, China
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Dongmei Su
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Jiantao Huo
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Guangjuan Yin
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Dong Dong
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Kaifang Duan
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Hong Cheng
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Huiling Xu
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Jiao Ma
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Dong Liu
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Bin Mou
- Institute of Life Science, Nanchang University, Nanchang, 330031, China
| | - Jiyun Peng
- Institute of Life Science, Nanchang University, Nanchang, 330031, China.
| | - Longzhen Cheng
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China.
- Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, China.
- Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, 518055, China.
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16
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Davis OC, Dickie AC, Mustapa MB, Boyle KA, Browne TJ, Gradwell MA, Smith KM, Polgár E, Bell AM, Kókai É, Watanabe M, Wildner H, Zeilhofer HU, Ginty DD, Callister RJ, Graham BA, Todd AJ, Hughes DI. Calretinin-expressing islet cells are a source of pre- and post-synaptic inhibition of non-peptidergic nociceptor input to the mouse spinal cord. Sci Rep 2023; 13:11561. [PMID: 37464016 PMCID: PMC10354228 DOI: 10.1038/s41598-023-38605-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 07/11/2023] [Indexed: 07/20/2023] Open
Abstract
Unmyelinated non-peptidergic nociceptors (NP afferents) arborise in lamina II of the spinal cord and receive GABAergic axoaxonic synapses, which mediate presynaptic inhibition. However, until now the source of this axoaxonic synaptic input was not known. Here we provide evidence that it originates from a population of inhibitory calretinin-expressing interneurons (iCRs), which correspond to lamina II islet cells. The NP afferents can be assigned to 3 functionally distinct classes (NP1-3). NP1 afferents have been implicated in pathological pain states, while NP2 and NP3 afferents also function as pruritoceptors. Our findings suggest that all 3 of these afferent types innervate iCRs and receive axoaxonic synapses from them, providing feedback inhibition of NP input. The iCRs also form axodendritic synapses, and their targets include cells that are themselves innervated by the NP afferents, thus allowing for feedforward inhibition. The iCRs are therefore ideally placed to control the input from non-peptidergic nociceptors and pruritoceptors to other dorsal horn neurons, and thus represent a potential therapeutic target for the treatment of chronic pain and itch.
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Affiliation(s)
- Olivia C Davis
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Allen C Dickie
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Marami B Mustapa
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
- Faculty of Medicine and Defence Health, National Defence University of Malaysia, 57000, Kuala Lumpur, Malaysia
| | - Kieran A Boyle
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Tyler J Browne
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Mark A Gradwell
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Kelly M Smith
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Erika Polgár
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Andrew M Bell
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Éva Kókai
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo, 060-8638, Japan
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zurich, 8057, Zürich, Switzerland
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, 8057, Zürich, Switzerland
| | - David D Ginty
- Department of Neurobiology, Howard Hughes Medical Institute, Harvard Medical School, 220 Longwood Avenue, Boston, MA, 02115, USA
| | - Robert J Callister
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Brett A Graham
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia.
| | - Andrew J Todd
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - David I Hughes
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
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17
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Davis OC, Dickie AC, Mustapa MB, Boyle KA, Browne TJ, Gradwell MA, Smith KM, Polgár E, Bell AM, Kókai É, Watanabe M, Wildner H, Zeilhofer HU, Ginty DD, Callister RJ, Graham BA, Todd AJ, Hughes DI. Calretinin-expressing islet cells: a source of pre- and post-synaptic inhibition of non-peptidergic nociceptor input to the mouse spinal cord. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.01.543241. [PMID: 37333120 PMCID: PMC10274676 DOI: 10.1101/2023.06.01.543241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Unmyelinated non-peptidergic nociceptors (NP afferents) arborise in lamina II of the spinal cord and receive GABAergic axoaxonic synapses, which mediate presynaptic inhibition. However, until now the source of this axoaxonic synaptic input was not known. Here we provide evidence that it originates from a population of inhibitory calretinin-expressing interneurons (iCRs), which correspond to lamina II islet cells. The NP afferents can be assigned to 3 functionally distinct classes (NP1-3). NP1 afferents have been implicated in pathological pain states, while NP2 and NP3 afferents also function as pruritoceptors. Our findings suggest that all 3 of these afferent types innervate iCRs and receive axoaxonic synapses from them, providing feedback inhibition of NP input. The iCRs also form axodendritic synapses, and their targets include cells that are themselves innervated by the NP afferents, thus allowing for feedforward inhibition. The iCRs are therefore ideally placed to control the input from non-peptidergic nociceptors and pruritoceptors to other dorsal horn neurons, and thus represent a potential therapeutic target for the treatment of chronic pain and itch.
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Affiliation(s)
- Olivia C. Davis
- School of Psychology and Neuroscience, Sir James Black Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Allen C. Dickie
- School of Psychology and Neuroscience, Sir James Black Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Marami B. Mustapa
- School of Psychology and Neuroscience, Sir James Black Building, University of Glasgow, Glasgow, G12 8QQ, UK
- Present address: Faculty of Medicine and Defence Health, National Defence University of Malaysia, 57000, Kuala Lumpur, Malaysia
| | - Kieran A. Boyle
- School of Psychology and Neuroscience, Sir James Black Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Tyler J. Browne
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Mark A. Gradwell
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Kelly M. Smith
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Erika Polgár
- School of Psychology and Neuroscience, Sir James Black Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Andrew M. Bell
- School of Psychology and Neuroscience, Sir James Black Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Éva Kókai
- School of Psychology and Neuroscience, Sir James Black Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo 060-8638, Japan
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - David D. Ginty
- Department of Neurobiology, Howard Hughes Medical Institute, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Robert J. Callister
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Brett A. Graham
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Andrew J. Todd
- School of Psychology and Neuroscience, Sir James Black Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - David I. Hughes
- School of Psychology and Neuroscience, Sir James Black Building, University of Glasgow, Glasgow, G12 8QQ, UK
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18
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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: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [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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19
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Huo J, Du F, Duan K, Yin G, Liu X, Ma Q, Dong D, Sun M, Hao M, Su D, Huang T, Ke J, Lai S, Zhang Z, Guo C, Sun Y, Cheng L. Identification of brain-to-spinal circuits controlling the laterality and duration of mechanical allodynia in mice. Cell Rep 2023; 42:112300. [PMID: 36952340 DOI: 10.1016/j.celrep.2023.112300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 12/22/2022] [Accepted: 03/07/2023] [Indexed: 03/24/2023] Open
Abstract
Mechanical allodynia (MA) represents one prevalent symptom of chronic pain. Previously we and others have identified spinal and brain circuits that transmit or modulate the initial establishment of MA. However, brain-derived descending pathways that control the laterality and duration of MA are still poorly understood. Here we report that the contralateral brain-to-spinal circuits, from Oprm1 neurons in the lateral parabrachial nucleus (lPBNOprm1), via Pdyn neurons in the dorsal medial regions of hypothalamus (dmHPdyn), to the spinal dorsal horn (SDH), act to prevent nerve injury from inducing contralateral MA and reduce the duration of bilateral MA induced by capsaicin. Ablating/silencing dmH-projecting lPBNOprm1 neurons or SDH-projecting dmHPdyn neurons, deleting Dyn peptide from dmH, or blocking spinal κ-opioid receptors all led to long-lasting bilateral MA. Conversely, activation of dmHPdyn neurons or their axonal terminals in SDH can suppress sustained bilateral MA induced by lPBN lesion.
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Affiliation(s)
- Jiantao Huo
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Feng Du
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Kaifang Duan
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Guangjuan Yin
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xi Liu
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Quan Ma
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Dong Dong
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Mengge Sun
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Mei Hao
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Dongmei Su
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Tianwen Huang
- Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China
| | - Jin Ke
- Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China
| | - Shishi Lai
- Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China
| | - Zhi Zhang
- Division of Life Sciences and Medicine, CAS Key Laboratory of Brain Function and Diseases, University of Science and Technology of China, Hefei 230027, China
| | - Chao Guo
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yuanjie Sun
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Longzhen Cheng
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China; Department of Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen 518055, China; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China.
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20
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Kuo SW, Zhang T, Esteller R, Grill WM. In Vivo Measurements reveal that both low- and high-frequency spinal cord stimulation heterogeneously modulate superficial dorsal horn neurons. Neuroscience 2023; 520:119-131. [PMID: 37085007 DOI: 10.1016/j.neuroscience.2023.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 03/01/2023] [Accepted: 04/08/2023] [Indexed: 04/23/2023]
Abstract
Current sub-perception spinal cord stimulation (SCS) is characterized by the use of high-frequency pulses to achieve paresthesia-free analgesic effects. High-frequency SCS demonstrates distinctive properties from paresthesia-based SCS, such as a longer time course to response, implying the existence of alternative mechanism(s) of action beyond gate control theory. We quantified the responses to SCS of single neurons within the superficial dorsal horn (SDH), a structure in close proximity to SCS electrodes, to investigate the mechanisms underlying high-frequency SCS in 62 urethane-anesthetized male rats. Sciatic nerve stimulation was delivered to isolate lumbar SDH neurons with evoked C-fiber activity. The evoked C-fiber activity before and after the application of SCS was compared to quantify the effects of SCS across stimulation intensity and stimulation duration at three different stimulation frequencies. We observed heterogeneous responses of SDH neurons which depended primarily on the type of unit. Low-threshold units with spontaneous activity, putatively inhibitory interneurons, tended to be facilitated by SCS while the other unit types were suppressed. The effects of SCS were more prominent with increased stimulation duration from 30 s to 30 m across frequencies. Our results highlight the importance of inhibitory interneurons in modulating local circuits of the SDH and the importance of local circuit contributions to the analgesic mechanisms of SCS.
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Affiliation(s)
- Su-Wei Kuo
- Department of Biomedical Engineering, Duke University, Durham, NC
| | - Tianhe Zhang
- Division of Neuromodulation, Boston Scientific Corporation, CA
| | - Rosana Esteller
- Division of Neuromodulation, Boston Scientific Corporation, CA
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC; Departments of Electrical and Computer Engineering, Neurobiology, and Neurosurgery, Duke University, Durham, NC.
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21
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Miranda CO, Hegedüs K, Kis G, Antal M. Synaptic Targets of Glycinergic Neurons in Laminae I-III of the Spinal Dorsal Horn. Int J Mol Sci 2023; 24:ijms24086943. [PMID: 37108107 PMCID: PMC10139066 DOI: 10.3390/ijms24086943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/04/2023] [Accepted: 04/07/2023] [Indexed: 04/29/2023] Open
Abstract
A great deal of evidence supports the inevitable importance of spinal glycinergic inhibition in the development of chronic pain conditions. However, it remains unclear how glycinergic neurons contribute to the formation of spinal neural circuits underlying pain-related information processing. Thus, we intended to explore the synaptic targets of spinal glycinergic neurons in the pain processing region (laminae I-III) of the spinal dorsal horn by combining transgenic technology with immunocytochemistry and in situ hybridization accompanied by light and electron microscopy. First, our results suggest that, in addition to neurons in laminae I-III, glycinergic neurons with cell bodies in lamina IV may contribute substantially to spinal pain processing. On the one hand, we show that glycine transporter 2 immunostained glycinergic axon terminals target almost all types of excitatory and inhibitory interneurons identified by their neuronal markers in laminae I-III. Thus, glycinergic postsynaptic inhibition, including glycinergic inhibition of inhibitory interneurons, must be a common functional mechanism of spinal pain processing. On the other hand, our results demonstrate that glycine transporter 2 containing axon terminals target only specific subsets of axon terminals in laminae I-III, including nonpeptidergic nociceptive C fibers binding IB4 and nonnociceptive myelinated A fibers immunoreactive for type 1 vesicular glutamate transporter, indicating that glycinergic presynaptic inhibition may be important for targeting functionally specific subpopulations of primary afferent inputs.
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Affiliation(s)
- Camila Oliveira Miranda
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Krisztina Hegedüs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Gréta Kis
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Miklós Antal
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
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22
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Franzen AD, Paulsen RT, Kabeiseman EJ, Burrell BD. Heterosynaptic long-term potentiation of non-nociceptive synapses requires endocannabinoids, NMDARs, CamKII, and PKCζ. J Neurophysiol 2023; 129:807-818. [PMID: 36883763 PMCID: PMC10085563 DOI: 10.1152/jn.00494.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/09/2023] Open
Abstract
Noxious stimuli or injury can trigger long-lasting sensitization to non-nociceptive stimuli (referred to as allodynia in mammals). Long-term potentiation (LTP) of nociceptive synapses has been shown to contribute to nociceptive sensitization (hyperalgesia) and there is even evidence of heterosynaptic spread of LTP contributing to this type of sensitization. This study will focus on how activation of nociceptors elicits heterosynaptic LTP (hetLTP) in non-nociceptive synapses. Previous studies in the medicinal leech (Hirudo verbana) have demonstrated that high-frequency stimulation (HFS) of nociceptors produces both homosynaptic LTP as well as hetLTP in non-nociceptive afferent synapses. This hetLTP involves endocannabinoid-mediated disinhibition of non-nociceptive synapses at the presynaptic level, but it is not clear if there are additional processes contributing to this synaptic potentiation. In this study, we found evidence for the involvement of postsynaptic level change and observed that postsynaptic N-methyl-d-aspartate (NMDA) receptors (NMDARs) were required for this potentiation. Next, Hirudo orthologs for known LTP signaling proteins, CamKII and PKCζ, were identified based on sequences from humans, mice, and the marine mollusk Aplysia. In electrophysiological experiments, inhibitors of CamKII (AIP) and PKCζ (ZIP) were found to interfere with hetLTP. Interestingly, CamKII was found to be necessary for both induction and maintenance of hetLTP, whereas PKCζ was only necessary for maintenance. These findings show that activation of nociceptors can elicit a potentiation of non-nociceptive synapses through a process that involves both endocannabinoid-mediated disinhibition and NMDAR-initiated signaling pathways.NEW & NOTEWORTHY Pain-related sensitization involves increases in signaling by non-nociceptive sensory neurons. This can allow non-nociceptive afferents to have access to nociceptive circuitry. In this study, we examine a form of synaptic potentiation in which nociceptor activity elicits increases in non-nociceptive synapses. This process involves endocannabinoids, "gating" the activation of NMDA receptors, which in turn activate CamKII and PKCζ. This study provides an important link in how nociceptive stimuli can enhance non-nociceptive signaling related to pain.
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Affiliation(s)
- Avery D Franzen
- Division of Basic Biomedical Sciences, Center for Brain and Behavior Research, Sanford School of Medicine, University of South Dakota, Vermillion, South Dakota, United States
| | - Riley T Paulsen
- Division of Basic Biomedical Sciences, Center for Brain and Behavior Research, Sanford School of Medicine, University of South Dakota, Vermillion, South Dakota, United States
| | - Emily J Kabeiseman
- Division of Basic Biomedical Sciences, Center for Brain and Behavior Research, Sanford School of Medicine, University of South Dakota, Vermillion, South Dakota, United States
| | - Brian D Burrell
- Division of Basic Biomedical Sciences, Center for Brain and Behavior Research, Sanford School of Medicine, University of South Dakota, Vermillion, South Dakota, United States
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23
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Li J, Serafin EK, Baccei ML. Intrinsic and synaptic properties of adult mouse spinoperiaqueductal gray neurons and the influence of neonatal tissue damage. Pain 2023; 164:905-917. [PMID: 36149785 PMCID: PMC10033328 DOI: 10.1097/j.pain.0000000000002787] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 09/09/2022] [Indexed: 11/26/2022]
Abstract
ABSTRACT The periaqueductal gray (PAG) represents a key target of projection neurons residing in the spinal dorsal horn. In comparison to lamina I spinoparabrachial neurons, little is known about the intrinsic and synaptic properties governing the firing of spino-PAG neurons, or whether such activity is modulated by neonatal injury. In this study, this issue was addressed using ex vivo whole-cell patch clamp recordings from lamina I spino-PAG neurons in adult male and female FVB mice after hindpaw incision at postnatal day (P)3. Spino-PAG neurons were classified as high output, medium output, or low output based on their action potential discharge after dorsal root stimulation. The high-output subgroup exhibited prevalent spontaneous burst firing and displayed initial burst or tonic patterns of intrinsic firing, whereas low-output neurons showed little spontaneous activity. Interestingly, the level of dorsal root-evoked firing significantly correlated with the resting potential and membrane resistance but not with the strength of primary afferent-mediated glutamatergic drive. Neonatal incision failed to alter the pattern of monosynaptic sensory input, with most spino-PAG neurons receiving direct connections from low-threshold C-fibers. Furthermore, primary afferent-evoked glutamatergic input and action potential discharge in adult spino-PAG neurons were unaltered by neonatal surgical injury. Finally, Hebbian long-term potentiation at sensory synapses, which significantly increased afferent-evoked firing, was similar between P3-incised and naive littermates. Collectively, these data suggest that the functional response of lamina I spino-PAG neurons to sensory input is largely governed by their intrinsic membrane properties and appears resistant to the persistent influence of neonatal tissue damage.
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Affiliation(s)
- Jie Li
- Department of Anesthesiology, Pain Research Center, University of Cincinnati Medical Center, Cincinnati, OH, United States
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24
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Rankin G, Chirila AM, Emanuel AJ, Zhang Z, Woolf CJ, Drugowitsch J, Ginty DD. Nerve injury disrupts temporal processing in the spinal cord dorsal horn through alterations in PV + interneurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.20.533541. [PMID: 36993199 PMCID: PMC10055222 DOI: 10.1101/2023.03.20.533541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
How mechanical allodynia following nerve injury is encoded in patterns of neural activity in the spinal cord dorsal horn (DH) is not known. We addressed this using the spared nerve injury model of neuropathic pain and in vivo electrophysiological recordings. Surprisingly, despite dramatic behavioral over-reactivity to mechanical stimuli following nerve injury, an overall increase in sensitivity or reactivity of DH neurons was not observed. We did, however, observe a marked decrease in correlated neural firing patterns, including the synchrony of mechanical stimulus-evoked firing, across the DH. Alterations in DH temporal firing patterns were recapitulated by silencing DH parvalbumin + (PV + ) inhibitory interneurons, previously implicated in mechanical allodynia, as were allodynic pain-like behaviors in mice. These findings reveal decorrelated DH network activity, driven by alterations in PV + interneurons, as a prominent feature of neuropathic pain, and suggest that restoration of proper temporal activity is a potential treatment for chronic neuropathic pain.
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25
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Natale CA, Christie MJ, Aubrey KR. Spinal glycinergic currents are reduced in a rat model of neuropathic pain following partial nerve ligation but not chronic constriction injury. J Neurophysiol 2023; 129:333-341. [PMID: 36541621 DOI: 10.1152/jn.00451.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Animal models have consistently indicated that central sensitization and the development of chronic neuropathic pain are linked to changes to inhibitory signaling in the dorsal horn of the spinal cord. However, replication of data investigating the cellular mechanisms that underlie these changes remains a challenge and there is still a lack of understanding about what aspects of spinal inhibitory transmission most strongly contribute to the disease. Here, we compared the effect of two different sciatic nerve injuries commonly used to generate rodent models of neuropathic pain on spinal glycinergic signaling. Using whole cell patch-clamp electrophysiology in spinal slices, we recorded from neurons in the lamina II of the dorsal horn and evoked inhibitory postsynaptic currents with a stimulator in lamina III, where glycinergic cell bodies are concentrated. We found that glycine inputs onto radial neurons were reduced following partial nerve ligation (PNL) of the sciatic nerve, consistent with a previous report. However, this finding was not replicated in animals that underwent chronic constriction injury (CCI) to the same nerve region. To limit the between-experiment variability, we kept the rat species, sex, and age consistent and had a single investigator carry out the surgeries. These data show that PNL and CCI cause divergent spinal signaling outcomes in the cord and add to the body of evidence suggesting that treatments for neuropathic pain should be triaged according to nerve injury or cellular dysfunction rather than the symptoms of the disease.NEW & NOTEWORTHY Neuropathic pain models are used in preclinical research to investigate the mechanisms underlying allodynia, a common symptom of neuropathic pain, and to test, develop, and validate therapies for persistent pain. We demonstrate that a glycinergic dysfunction is consistently associated with partial nerve ligation but not the chronic constriction injury model. This suggests that the cellular effects produced by each injury are distinct and that data from different neuropathic pain models should be considered separately.
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Affiliation(s)
- Claudia A Natale
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Camperdown, New South Wales, Australia
| | - Macdonald J Christie
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Camperdown, New South Wales, Australia
| | - Karin R Aubrey
- Pain Management Research, Kolling Institute, Royal North Shore Hospital, St Leonards, New South Wales, Australia.,Northern Clinical School, Faculty of Medicine and Health, University of Sydney, Camperdown, New South Wales, Australia
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26
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Time-dependent and selective microglia-mediated removal of spinal synapses in neuropathic pain. Cell Rep 2023; 42:112010. [PMID: 36656715 DOI: 10.1016/j.celrep.2023.112010] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 09/20/2022] [Accepted: 01/03/2023] [Indexed: 01/20/2023] Open
Abstract
Neuropathic pain is a debilitating condition resulting from damage to the nervous system. Imbalance of spinal excitation and inhibition has been proposed to contribute to neuropathic pain. However, the structural basis of this imbalance remains unknown. Using a preclinical model of neuropathic pain, we show that microglia selectively engulf spinal synapses that are formed by central neurons and spare those of peripheral sensory neurons. Furthermore, we reveal that removal of inhibitory and excitatory synapses exhibits distinct temporal patterns, in which microglia-mediated inhibitory synapse removal precedes excitatory synapse removal. We also find selective and gradual increase in complement depositions on dorsal horn synapses that corresponds to the temporal pattern of microglial synapse pruning activity and type-specific synapse loss. Together, these results define a specific role for microglia in the progression of neuropathic pain pathogenesis and implicate these immune cells in structural remodeling of dorsal horn circuitry.
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27
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Differences between Maximum Tongue Force in Women Suffering from Chronic and Asymptomatic Temporomandibular Disorders-An Observational Study. Life (Basel) 2023; 13:life13010229. [PMID: 36676178 PMCID: PMC9866298 DOI: 10.3390/life13010229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/04/2023] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
Background: Temporomandibular disorders are craniofacial disorders characterized by the presence of chronic pain in masticatory muscles, with higher incidence in the women population. There is little research that has studied tongue force related to temporomandibular disorders, but there are a lot of studies that have demonstrated the impact of tongue force in vital functions, such as chewing, swallowing, phonation, or breathing. According to this, the aim of this study was to compare the maximum force of the tongue between females with chronic temporomandibular disorders and asymptomatic females. We also wanted to establish whether any relationship existed between the pain and fatigue versus the maximum force developed in females with chronic temporomandibular disorders. Material and methods: A cross-sectional study of 67 women between the ages of 18 and 65 years old was performed. The included women were assigned to one of two groups, according to whether they had chronic temporomandibular disorders or not. The procedure was the same for both groups. Outcome measures included the maximum tongue force, intensity of perceived orofacial pain, and intensity of perceived orofacial fatigue. Results: The results showed significant statistical differences for the maximum tongue force measurement between the chronic temporomandibular disorders group and the control group (p < 0.05) for all the movements, except the lip pressure measurement. Furthermore, the analysis revealed significant statistical differences between the intensity of perceived orofacial fatigue between the groups (p < 0.05). Moreover, the data showed no significant correlations between variables. Conclusion: The study found significant differences in maximum tongue force when comparing women with chronic temporomandibular disorders and asymptomatic women (being superior in these). Likewise, we found that the intensity of perceived orofacial fatigue after tongue exercises showed significant differences between groups. However, this study reveals no correlations between the intensity of perceived orofacial pain and fatigue and the maximum tongue force.
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28
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Albisetti GW, Ganley RP, Pietrafesa F, Werynska K, Magalhaes de Sousa M, Sipione R, Scheurer L, Bösl MR, Pelczar P, Wildner H, Zeilhofer HU. Inhibitory Kcnip2 neurons of the spinal dorsal horn control behavioral sensitivity to environmental cold. Neuron 2023; 111:92-105.e5. [PMID: 36323322 PMCID: PMC9831669 DOI: 10.1016/j.neuron.2022.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 08/16/2022] [Accepted: 10/04/2022] [Indexed: 11/12/2022]
Abstract
Proper sensing of ambient temperature is of utmost importance for the survival of euthermic animals, including humans. While considerable progress has been made in our understanding of temperature sensors and transduction mechanisms, the higher-order neural circuits processing such information are still only incompletely understood. Using intersectional genetics in combination with circuit tracing and functional neuron manipulation, we identified Kcnip2-expressing inhibitory (Kcnip2GlyT2) interneurons of the mouse spinal dorsal horn as critical elements of a neural circuit that tunes sensitivity to cold. Diphtheria toxin-mediated ablation of these neurons increased cold sensitivity without affecting responses to other somatosensory modalities, while their chemogenetic activation reduced cold and also heat sensitivity. We also show that Kcnip2GlyT2 neurons become activated preferentially upon exposure to cold temperatures and subsequently inhibit spinal nociceptive output neurons that project to the lateral parabrachial nucleus. Our results thus identify a hitherto unknown spinal circuit that tunes cold sensitivity.
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Affiliation(s)
- Gioele W. Albisetti
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Robert P. Ganley
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Francesca Pietrafesa
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Karolina Werynska
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | | | - Rebecca Sipione
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Louis Scheurer
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Michael R. Bösl
- Institute of Experimental Biomedicine I, University Hospital Würzburg, and Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Pawel Pelczar
- Center for Transgenic Models, University of Basel, 4001 Basel, Switzerland
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland,Corresponding author
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland,Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, 8093 Zürich, Switzerland,Center for Neuroscience Zurich (ZNZ), 8057 Zürich, Switzerland,Drug Discovery Network Zurich (DDNZ), 8057 Zürich, Switzerland,Corresponding author
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29
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Grpr expression defines a population of superficial dorsal horn vertical cells that have a role in both itch and pain. Pain 2023; 164:149-170. [PMID: 35543635 PMCID: PMC9756441 DOI: 10.1097/j.pain.0000000000002677] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 04/06/2022] [Indexed: 01/09/2023]
Abstract
ABSTRACT Neurons in the superficial dorsal horn that express the gastrin-releasing peptide receptor (GRPR) are strongly implicated in spinal itch pathways. However, a recent study reported that many of these correspond to vertical cells, a population of interneurons that are believed to transmit nociceptive information. In this study, we have used a GRPR CreERT2 mouse line to identify and target cells that possess Grpr mRNA. We find that the GRPR cells are highly concentrated in lamina I and the outer part of lamina II, that they are all glutamatergic, and that they account for ∼15% of the excitatory neurons in the superficial dorsal horn. We had previously identified 6 neurochemically distinct excitatory interneuron populations in this region based on neuropeptide expression and the GRPR cells are largely separate from these, although they show some overlap with cells that express substance P. Anatomical analysis revealed that the GRPR neurons are indeed vertical cells, and that their axons target each other, as well as arborising in regions that contain projection neurons: lamina I, the lateral spinal nucleus, and the lateral part of lamina V. Surprisingly, given the proposed role of GRPR cells in itch, we found that most of the cells received monosynaptic input from Trpv1-expressing (nociceptive) afferents, that the majority responded to noxious and pruritic stimuli, and that chemogenetically activating them resulted in pain-related and itch-related behaviours. Together, these findings suggest that the GRPR cells are involved in spinal cord circuits that underlie both pain and itch.
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30
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McDonough KE, Hammond R, Wang J, Tierney J, Hankerd K, Chung JM, La JH. Spinal GABAergic disinhibition allows microglial activation mediating the development of nociplastic pain in male mice. Brain Behav Immun 2023; 107:215-224. [PMID: 36273650 PMCID: PMC9855286 DOI: 10.1016/j.bbi.2022.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 10/14/2022] [Accepted: 10/15/2022] [Indexed: 11/05/2022] Open
Abstract
Previously we developed a murine model in which postinjury stimulation of an injured area triggers a transition to a nociplastic pain state manifesting as persistent mechanical hypersensitivity outside of the previously injured area. This hypersensitivity was maintained by sex-specific mechanisms; specifically, activated spinal microglia maintained the hypersensitivity only in males. Here we investigated whether spinal microglia drive the transition from acute injury-induced pain to nociplastic pain in males, and if so, how they are activated by normally innocuous stimulation after peripheral injury. Using intraplantar capsaicin injection as an acute peripheral injury and vibration of the injured paw as postinjury stimulation, we found that inhibition of spinal microglia prevents the vibration-induced transition to a nociplastic pain state. The transition was mediated by the ATP-P2X4 pathway, but not BDNF-TrkB signaling. Intrathecally injected GABA receptor agonists after intraplantar capsaicin injection prevented the vibration-induced transition to a nociplastic pain state. Conversely, in the absence of intraplantar capsaicin injection, intrathecally injected GABA receptor antagonists allowed the vibration stimulation of a normal paw to trigger the transition to a spinal microglia-mediated nociplastic pain state only in males. At the spinal level, TNF-α, IL-1β, and IL-6, but not prostaglandins, contributed to the maintenance of the nociplastic pain state in males. These results demonstrate that in males, the transition from acute injury-induced pain to nociplastic pain is driven by spinal microglia causing neuroinflammation and that peripheral injury-induced spinal GABAergic disinhibition is pivotal for normally innocuous stimulation to activate spinal microglia.
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Affiliation(s)
- Kathleen E McDonough
- Department of Neurobiology, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555, United States
| | - Regan Hammond
- Department of Neurobiology, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555, United States
| | - Jigong Wang
- Department of Neurobiology, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555, United States
| | - Jessica Tierney
- Department of Neurobiology, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555, United States
| | - Kali Hankerd
- Department of Neurobiology, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555, United States
| | - Jin Mo Chung
- Department of Neurobiology, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555, United States
| | - Jun-Ho La
- Department of Neurobiology, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555, United States.
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31
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Cao B, Scherrer G, Chen L. Spinal cord retinoic acid receptor signaling gates mechanical hypersensitivity in neuropathic pain. Neuron 2022; 110:4108-4124.e6. [PMID: 36223767 PMCID: PMC9789181 DOI: 10.1016/j.neuron.2022.09.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 08/27/2022] [Accepted: 09/22/2022] [Indexed: 02/08/2023]
Abstract
Central sensitization caused by spinal disinhibition is a key mechanism of mechanical allodynia in neuropathic pain. However, the molecular mechanisms underlying spinal disinhibition after nerve injury remain unclear. Here, we show in mice that spared nerve injury (SNI), which induces mechanical hypersensitivity and neuropathic pain, triggers homeostatic reduction of inhibitory outputs from dorsal horn parvalbumin-positive (PV+) interneurons onto both primary afferent terminals and excitatory interneurons. The reduction in inhibitory outputs drives hyperactivation of the spinal cord nociceptive pathway, causing mechanical hypersensitivity. We identified the retinoic acid receptor RARα, a central regulator of homeostatic plasticity, as the key molecular mediator for this synaptic disinhibition. Deletion of RARα in spinal PV+ neurons or application of an RARα antagonist in the spinal cord prevented the development of SNI-induced mechanical hypersensitivity. Our results identify RARα as a crucial molecular effector for neuropathic pain and a potential target for its treatment.
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Affiliation(s)
- Bing Cao
- Department of Neurosurgery, Wu Tsai Neuroscience Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Gregory Scherrer
- Department of Cell Biology and Physiology, UNC Neuroscience Center, Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Lu Chen
- Department of Neurosurgery, Wu Tsai Neuroscience Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
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32
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Chirila AM, Rankin G, Tseng SY, Emanuel AJ, Chavez-Martinez CL, Zhang D, Harvey CD, Ginty DD. Mechanoreceptor signal convergence and transformation in the dorsal horn flexibly shape a diversity of outputs to the brain. Cell 2022; 185:4541-4559.e23. [PMID: 36334588 PMCID: PMC9691598 DOI: 10.1016/j.cell.2022.10.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 08/22/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022]
Abstract
The encoding of touch in the spinal cord dorsal horn (DH) and its influence on tactile representations in the brain are poorly understood. Using a range of mechanical stimuli applied to the skin, large-scale in vivo electrophysiological recordings, and genetic manipulations, here we show that neurons in the mouse spinal cord DH receive convergent inputs from both low- and high-threshold mechanoreceptor subtypes and exhibit one of six functionally distinct mechanical response profiles. Genetic disruption of DH feedforward or feedback inhibitory motifs, comprised of interneurons with distinct mechanical response profiles, revealed an extensively interconnected DH network that enables dynamic, flexible tuning of postsynaptic dorsal column (PSDC) output neurons and dictates how neurons in the primary somatosensory cortex respond to touch. Thus, mechanoreceptor subtype convergence and non-linear transformations at the earliest stage of the somatosensory hierarchy shape how touch of the skin is represented in the brain.
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Affiliation(s)
- Anda M Chirila
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Genelle Rankin
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Shih-Yi Tseng
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Alan J Emanuel
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Carmine L Chavez-Martinez
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Dawei Zhang
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Christopher D Harvey
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - David D Ginty
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA.
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Warwick C, Salsovic J, Hachisuka J, Smith KM, Sheahan TD, Chen H, Ibinson J, Koerber HR, Ross SE. Cell type-specific calcium imaging of central sensitization in mouse dorsal horn. Nat Commun 2022; 13:5199. [PMID: 36057681 PMCID: PMC9440908 DOI: 10.1038/s41467-022-32608-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 08/08/2022] [Indexed: 01/12/2023] Open
Abstract
Allodynia is a state in which pain is elicited by innocuous stimuli. Capsaicin applied to the skin results in an allodynia that extends to a broad region beyond the application site. This sensitization is thought to be mediated by spinal networks; however, we do not have a clear picture of which spinal neurons mediate this phenomenon. To address this gap, we used two-photon calcium imaging of excitatory interneurons and spinal projection neurons in the mouse spinal dorsal horn. To distinguish among neuronal subtypes, we developed CICADA, a cell profiling approach to identify cell types during calcium imaging. We then identified capsaicin-responsive and capsaicin-sensitized neuronal populations. Capsaicin-sensitized neurons showed emergent responses to innocuous input and increased receptive field sizes consistent with psychophysical reports. Finally, we identified spinal output neurons that showed enhanced responses from innocuous input. These experiments provide a population-level view of central sensitization and a framework with which to model somatosensory integration in the dorsal horn.
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Affiliation(s)
- Charles Warwick
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - Joseph Salsovic
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - Junichi Hachisuka
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
- Spinal Cord Group, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | - Kelly M Smith
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tayler D Sheahan
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - Haichao Chen
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA
- School of Medicine, Tsinghua University, Beijing, China
| | - James Ibinson
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - H Richard Koerber
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Sarah E Ross
- Department of Neurobiology and the Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA.
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA, USA.
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Thalhammer A, Fontanini M, Shi J, Scaini D, Recupero L, Evtushenko A, Fu Y, Pavagada S, Bistrovic-Popov A, Fruk L, Tian B, Ballerini L. Distributed interfacing by nanoscale photodiodes enables single-neuron light activation and sensory enhancement in 3D spinal explants. SCIENCE ADVANCES 2022; 8:eabp9257. [PMID: 35960795 PMCID: PMC9374338 DOI: 10.1126/sciadv.abp9257] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 06/29/2022] [Indexed: 05/29/2023]
Abstract
Among emerging technologies developed to interface neuronal signaling, engineering electrodes at the nanoscale would yield more precise biodevices opening to progress in neural circuit investigations and to new therapeutic potential. Despite remarkable progress in miniature electronics for less invasive neurostimulation, most nano-enabled, optically triggered interfaces are demonstrated in cultured cells, which precludes the studies of natural neural circuits. We exploit here free-standing silicon-based nanoscale photodiodes to optically modulate single, identified neurons in mammalian spinal cord explants. With near-infrared light stimulation, we show that activating single excitatory or inhibitory neurons differently affects sensory circuits processing in the dorsal horn. We successfully functionalize nano-photodiodes to target single molecules, such as glutamate AMPA receptor subunits, thus enabling light activation of specific synaptic pathways. We conclude that nano-enabled neural interfaces can modulate selected sensory networks with low invasiveness. The use of nanoscale photodiodes can thus provide original perspective in linking neural activity to specific behavioral outcome.
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Affiliation(s)
- Agnes Thalhammer
- International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
| | - Mario Fontanini
- International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
| | - Jiuyun Shi
- Department of Chemistry, University of Chicago, Chicago, IL, USA
| | - Denis Scaini
- International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
- Elettra Sincrotrone Trieste S.C.p.A., Area Science Park, I-34149 Trieste, Italy
- Basque Foundation for Science, Ikerbasque, Bilbao 48013, Spain
- Universidad del País Vasco (UPV/EHU), Barrio Sarriena s/n, 48940 Leioa, Spain
| | - Luca Recupero
- International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
| | - Alexander Evtushenko
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Ying Fu
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Suraj Pavagada
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Andrea Bistrovic-Popov
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Ljiljana Fruk
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Bozhi Tian
- Department of Chemistry, University of Chicago, Chicago, IL, USA
| | - Laura Ballerini
- International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
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Pre-Synaptic GABAA in NaV1.8+ Primary Afferents Is Required for the Development of Punctate but Not Dynamic Mechanical Allodynia following CFA Inflammation. Cells 2022; 11:cells11152390. [PMID: 35954234 PMCID: PMC9368720 DOI: 10.3390/cells11152390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/26/2022] [Accepted: 07/27/2022] [Indexed: 01/27/2023] Open
Abstract
Hypersensitivity to mechanical stimuli is a cardinal symptom of neuropathic and inflammatory pain. A reduction in spinal inhibition is generally considered a causal factor in the development of mechanical hypersensitivity after injury. However, the extent to which presynaptic inhibition contributes to altered spinal inhibition is less well established. Here, we used conditional deletion of GABAA in NaV1.8-positive sensory neurons (Scn10aCre;Gabrb3fl/fl) to manipulate selectively presynaptic GABAergic inhibition. Behavioral testing showed that the development of inflammatory punctate allodynia was mitigated in mice lacking pre-synaptic GABAA. Dorsal horn cellular circuits were visualized in single slices using stimulus-tractable dual-labelling of c-fos mRNA for punctate and the cognate c-Fos protein for dynamic mechanical stimulation. This revealed a substantial reduction in the number of cells activated by punctate stimulation in mice lacking presynaptic GABAA and an approximate 50% overlap of the punctate with the dynamic circuit, the relative percentage of which did not change following inflammation. The reduction in dorsal horn cells activated by punctate stimuli was equally prevalent in parvalbumin- and calretinin-positive cells and across all laminae I–V, indicating a generalized reduction in spinal input. In peripheral DRG neurons, inflammation following complete Freund’s adjuvant (CFA) led to an increase in axonal excitability responses to GABA, suggesting that presynaptic GABA effects in NaV1.8+ afferents switch from inhibition to excitation after CFA. In the days after inflammation, presynaptic GABAA in NaV1.8+ nociceptors constitutes an “open gate” pathway allowing mechanoreceptors responding to punctate mechanical stimulation access to nociceptive dorsal horn circuits.
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Omara-Reda H, Ouachikh O, Hamdi D, Dieb W, Lashin M, Durif F, Hafidi A. Naltrexone promotes mechanical allodynia in humans and rats. Neurosci Lett 2022; 786:136816. [PMID: 35901909 DOI: 10.1016/j.neulet.2022.136816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 07/19/2022] [Accepted: 07/22/2022] [Indexed: 11/30/2022]
Abstract
Mechanical allodynia has been studied in chronic naltrexone-treated people (N.T.P.) and rats (N.T.R.). After persistent naltrexone administration, patients acquired static and dynamic mechanical allodynia, as measured by von Frey filament (vFf) and brush stimulations. Pregabalin and levodopa administrations in N.T.P. significantly reduced allodynic behaviour, albeit these molecules did not completely stop it. As evidenced by the deployment of the vFf, subchronic treatment with Naltrexone delivered peripherally or intrathecally induced allodynic behaviour in rats. Increased expressions of two pain markers, pERK1/2 and PKCγ, in the spinal dorsal horn laminae were associated with naltrexone-induced allodynic behaviour. After vFf stimulation, pERK1/2 expression was substantially higher (p < 0.001) in superficial spinal dorsal horn laminae than in non-stimulated or naive non-stimulated rats. In addition, when compared to control rats, N.T.R. showed a substantial (p < 0.001) increase in PKCγ expression. PKCγ expression was found to be strong in lamina IIi and laminae III-IV. A cellular mechanism is proposed for the naltrexone effect. In both people and rats, Naltrexone induces static mechanical allodynia, according to this study.
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Affiliation(s)
- Hend Omara-Reda
- Université Clermont Auvergne, TGI, CNRS, Clermont Auvergne INP, Institut Pascal, 63000 Clermont-Ferrand, France
| | - Omar Ouachikh
- Université Clermont Auvergne, TGI, CNRS, Clermont Auvergne INP, Institut Pascal, 63000 Clermont-Ferrand, France.
| | - Dhouha Hamdi
- Université Clermont Auvergne, TGI, CNRS, Clermont Auvergne INP, Institut Pascal, 63000 Clermont-Ferrand, France.
| | - Wisam Dieb
- Université Clermont Auvergne, TGI, CNRS, Clermont Auvergne INP, Institut Pascal, 63000 Clermont-Ferrand, France
| | - Mohamed Lashin
- Université Clermont Auvergne, TGI, CNRS, Clermont Auvergne INP, Institut Pascal, 63000 Clermont-Ferrand, France
| | - Franck Durif
- Université Clermont Auvergne, TGI, CNRS, Clermont Auvergne INP, Institut Pascal, 63000 Clermont-Ferrand, France.
| | - Aziz Hafidi
- Université Clermont Auvergne, TGI, CNRS, Clermont Auvergne INP, Institut Pascal, 63000 Clermont-Ferrand, France.
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37
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Leonardon B, Cathenaut L, Vial-Markiewicz L, Hugel S, Schlichter R, Inquimbert P. Modulation of GABAergic Synaptic Transmission by NMDA Receptors in the Dorsal Horn of the Spinal Cord. Front Mol Neurosci 2022; 15:903087. [PMID: 35860500 PMCID: PMC9289521 DOI: 10.3389/fnmol.2022.903087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 05/31/2022] [Indexed: 12/30/2022] Open
Abstract
The dorsal horn (DH) of the spinal cord is an important structure involved in the integration of nociceptive messages. Plastic changes in the properties of neuronal networks in the DH underlie the development of analgesia as well as of hyperalgesia and allodynia in acute and chronic pain states. Two key mechanisms are involved in these chronic pain states: increased electrical activities and glutamate release leading to the recruitment of NMDAr and plastic changes in the synaptic inhibition. Although: (1) the balance between excitation and inhibition is known to play a critical role in the spinal network; and (2) plastic changes in spinal excitation and inhibition have been studied separately, the relationship between these two mechanisms has not been investigated in detail. In the present work, we addressed the role of NMDA receptors in the modulation of GABAergic synaptic transmission in the DH network. Using tight-seal whole-cell recordings on adult mice DH neurons, we characterized the effect of NMDAr activation on inhibitory synaptic transmission and more especially on the GABAergic one. Our results show that, in a subset of neurons recorded in lamina II, NMDAr activation facilitates spontaneous and miniature GABAergic synaptic transmission with a target specificity on GABAergic interneurons. In contrast, NMDA reduced the mean amplitude of evoked GABAergic IPSCs. These results show that NMDAr modulate GABAergic transmission by a presynaptic mechanism of action. Using a pharmacological approach, we investigated the composition of NMDAr involved in this modulation of GABAergic synaptic transmission. We found that the NMDA-induced facilitation was mediated by the activation of NMDAr containing GluN2C/D subunits. Altogether, our results bring new insights on nociceptive information processing in the spinal cord network and plastic changes in synaptic inhibition that could underlie the development and maintenance of chronic pain.
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Affiliation(s)
- Benjamin Leonardon
- Centre National de la Recherche Scientifique, UPR 3212 Institute of Cellular and Integrative Neurosciences, Strasbourg, France
- Université de Strasbourg, Strasbourg, France
| | - Lou Cathenaut
- Centre National de la Recherche Scientifique, UPR 3212 Institute of Cellular and Integrative Neurosciences, Strasbourg, France
- Université de Strasbourg, Strasbourg, France
| | - Louise Vial-Markiewicz
- Centre National de la Recherche Scientifique, UPR 3212 Institute of Cellular and Integrative Neurosciences, Strasbourg, France
- Université de Strasbourg, Strasbourg, France
| | - Sylvain Hugel
- Centre National de la Recherche Scientifique, UPR 3212 Institute of Cellular and Integrative Neurosciences, Strasbourg, France
| | - Rémy Schlichter
- Centre National de la Recherche Scientifique, UPR 3212 Institute of Cellular and Integrative Neurosciences, Strasbourg, France
- Université de Strasbourg, Strasbourg, France
| | - Perrine Inquimbert
- Centre National de la Recherche Scientifique, UPR 3212 Institute of Cellular and Integrative Neurosciences, Strasbourg, France
- Université de Strasbourg, Strasbourg, France
- *Correspondence: Perrine Inquimbert
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Wang LB, Su XJ, Wu QF, Xu X, Wang XY, Chen M, Ye JR, Maimaitiabula A, Liu XQ, Sun W, Zhang Y. Parallel Spinal Pathways for Transmitting Reflexive and Affective Dimensions of Nocifensive Behaviors Evoked by Selective Activation of the Mas-Related G Protein-Coupled Receptor D-Positive and Transient Receptor Potential Vanilloid 1-Positive Subsets of Nociceptors. Front Cell Neurosci 2022; 16:910670. [PMID: 35693883 PMCID: PMC9175034 DOI: 10.3389/fncel.2022.910670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/04/2022] [Indexed: 11/29/2022] Open
Abstract
The high incidence of treatment-resistant pain calls for the urgent preclinical translation of new analgesics. Understanding the behavioral readout of pain in animals is crucial for efficacy evaluation when developing novel analgesics. Mas-related G protein-coupled receptor D-positive (Mrgprd+) and transient receptor potential vanilloid 1-positive (TRPV1+) sensory neurons are two major non-overlapping subpopulations of C-fiber nociceptors. Their activation has been reported to provoke diverse nocifensive behaviors. However, what kind of behavior reliably represents subjectively conscious pain perception needs to be revisited. Here, we generated transgenic mice in which Mrgprd+ or TRPV1+ sensory neurons specifically express channelrhodopsin-2 (ChR2). Under physiological conditions, optogenetic activation of hindpaw Mrgprd+ afferents evoked reflexive behaviors (lifting, etc.), but failed to produce aversion. In contrast, TRPV1+ afferents activation evoked marked reflexive behaviors and affective responses (licking, etc.), as well as robust aversion. Under neuropathic pain conditions induced by spared nerve injury (SNI), affective behaviors and avoidance can be elicited by Mrgprd+ afferents excitation. Mechanistically, spinal cord-lateral parabrachial nucleus (lPBN) projecting neurons in superficial layers (lamina I–IIo) were activated by TRPV1+ nociceptors in naïve conditions or by Mrgprd+ nociceptors after SNI, whereas only deep spinal cord neurons were activated by Mrgprd+ nociceptors in naïve conditions. Moreover, the excitatory inputs from Mrgprd+ afferents to neurons within inner lamina II (IIi) are partially gated under normal conditions. Altogether, we conclude that optogenetic activation of the adult Mrgprd+ nociceptors drives non-pain-like reflexive behaviors via the deep spinal cord pathway under physiological conditions and drives pain-like affective behaviors via superficial spinal cord pathway under pathological conditions. The distinct spinal pathway transmitting different forms of nocifensive behaviors provides different therapeutic targets. Moreover, this study appeals to the rational evaluation of preclinical analgesic efficacy by using comprehensive and suitable behavioral assays, as well as by assessing neural activity in the two distinct pathways.
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Affiliation(s)
- Liang-Biao Wang
- Stroke Center & Department of Neurology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Xiao-Jing Su
- Stroke Center & Department of Neurology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Qiao-Feng Wu
- Stroke Center & Department of Neurology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Xiang Xu
- Stroke Center & Department of Neurology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Xin-Yue Wang
- Stroke Center & Department of Neurology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Mo Chen
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Jia-Reng Ye
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Abasi Maimaitiabula
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Xiao-Qing Liu
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Wen Sun
- Stroke Center & Department of Neurology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Wen Sun,
| | - Yan Zhang
- Stroke Center & Department of Neurology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- *Correspondence: Yan Zhang,
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Homeostatic plasticity and excitation-inhibition balance: The good, the bad, and the ugly. Curr Opin Neurobiol 2022; 75:102553. [PMID: 35594578 DOI: 10.1016/j.conb.2022.102553] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 02/15/2022] [Accepted: 04/13/2022] [Indexed: 12/12/2022]
Abstract
In this review, we discuss the significance of the synaptic excitation/inhibition (E/I) balance in the context of homeostatic plasticity, whose primary goal is thought to maintain neuronal firing rates at a set point. We first provide an overview of the processes through which patterned input activity drives synaptic E/I tuning and maturation of circuits during development. Next, we emphasize the importance of the E/I balance at the synaptic level (homeostatic control of message reception) as a means to achieve the goal (homeostatic control of information transmission) at the network level and consider how compromised homeostatic plasticity associated with neurological diseases leads to hyperactivity, network instability, and ultimately improper information processing. Lastly, we highlight several pathological conditions related to sensory deafferentation and describe how, in some cases, homeostatic compensation without appropriate sensory inputs can result in phantom perceptions.
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Mack D, Yevugah A, Renner K, Burrell BD. Serotonin mediates stress-like effects on responses to non-nociceptive stimuli in Hirudo. J Exp Biol 2022; 225:275639. [PMID: 35510636 PMCID: PMC9234501 DOI: 10.1242/jeb.243404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 04/29/2022] [Indexed: 11/28/2022]
Abstract
Noxious stimuli can elicit stress in animals that produce a variety of adaptations including changes in responses to nociceptive and non-nociceptive sensory input. One example is stress-induced analgesia that may be mediated, in part, by the endocannabinoid system. However, endocannabinoids can also have pro-nociceptive effects. In this study, the effects of electroshock, one experimental approach for producing acute stress, were examined on responses to non-nociceptive mechanical stimuli and nociceptive thermal stimuli in the medicinal leech (Hirudo verbana). The electroshock stimuli did not alter the leeches’ responses to nociceptive stimuli, but did cause sensitization to non-nociceptive stimuli, characterized by a reduction in response threshold. These experiments were repeated with drugs that either blocked synthesis of the endocannabinoid transmitter 2-arachidonoylglycerol (2-AG) or transient receptor potential vanilloid (TRPV) channel, which is known to act as an endocannabinoid receptor. Surprisingly, neither treatment had any effect on responses following electroshock. However, the electroshock stimuli reliably increased serotonin (5-hydroxytryptamine or 5HT) levels in the H. verbana CNS. Injection of 5HT mimicked the effects of the electroshocks, sensitizing responses to non-nociceptive stimuli and having no effect on responses to nociceptive stimuli. Injections of the 5HT receptor antagonist methysergide reduced the sensitization effect to non-nociceptive stimuli after electroshock treatment. These results indicate that electroshocks enhance response to non-nociceptive stimuli but do not alter responses to nociceptive stimuli. Furthermore, while 5HT appears to play a critical role in this shock-induced sensitizing effect, the endocannabinoid system seems to have no effect. Summary: The role of serotonin and endocannabinoids in mediating the effects of potentially stress-inducing stimuli on Hirudo verbana’s response to nociceptive and non-nociceptive input.
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Affiliation(s)
- Danielle Mack
- Division of Basic Biomedical Sciences, University of South Dakota, USA.,Center for Brain and Behavior Research, University of South Dakota, USA
| | | | - Kenneth Renner
- Department of Biology, University of South Dakota, USA.,Center for Brain and Behavior Research, University of South Dakota, USA
| | - Brian D Burrell
- Division of Basic Biomedical Sciences, University of South Dakota, USA.,Center for Brain and Behavior Research, University of South Dakota, USA
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El Khoueiry C, Alba-Delgado C, Antri M, Gutierrez-Mecinas M, Todd AJ, Artola A, Dallel R. GABAA and Glycine Receptor-Mediated Inhibitory Synaptic Transmission onto Adult Rat Lamina IIi PKCγ-Interneurons: Pharmacological but not Anatomical Specialization. Cells 2022; 11:cells11081356. [PMID: 35456035 PMCID: PMC9033052 DOI: 10.3390/cells11081356] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/07/2022] [Accepted: 04/13/2022] [Indexed: 11/16/2022] Open
Abstract
Mechanical allodynia (pain to normally innocuous tactile stimuli) is a widespread symptom of inflammatory and neuropathic pain. Spinal or medullary dorsal horn (SDH or MDH) circuits mediating tactile sensation and pain need to interact in order to evoke mechanical allodynia. PKCγ-expressing (PKCγ+) interneurons and inhibitory controls within SDH/MDH inner lamina II (IIi) are pivotal in connecting touch and pain circuits. However, the relative contribution of GABA and glycine to PKCγ+ interneuron inhibition remains unknown. We characterized inhibitory inputs onto PKCγ+ interneurons by combining electrophysiology to record spontaneous and miniature IPSCs (sIPSCs, mIPSCs) and immunohistochemical detection of GABAARα2 and GlyRα1 subunits in adult rat MDH. While GlyR-only- and GABAAR-only-mediated mIPSCs/sIPSCs are predominantly recorded from PKCγ+ interneurons, immunohistochemistry reveals that ~80% of their inhibitory synapses possess both GABAARα2 and GlyRα1. Moreover, nearly all inhibitory boutons at gephyrin-expressing synapses on these cells contain glutamate decarboxylase and are therefore GABAergic, with around half possessing the neuronal glycine transporter (GlyT2) and therefore being glycinergic. Thus, while GABA and glycine are presumably co-released and GABAARs and GlyRs are present at most inhibitory synapses on PKCγ+ interneurons, these interneurons exhibit almost exclusively GABAAR-only and GlyR-only quantal postsynaptic inhibitory currents, suggesting a pharmacological specialization of their inhibitory synapses.
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Affiliation(s)
- Corinne El Khoueiry
- Neuro-Dol, Inserm, Université Clermont Auvergne, CHU Clermont-Ferrand, F-63000 Clermont-Ferrand, France; (C.E.K.); (C.A.-D.); (M.A.)
| | - Cristina Alba-Delgado
- Neuro-Dol, Inserm, Université Clermont Auvergne, CHU Clermont-Ferrand, F-63000 Clermont-Ferrand, France; (C.E.K.); (C.A.-D.); (M.A.)
| | - Myriam Antri
- Neuro-Dol, Inserm, Université Clermont Auvergne, CHU Clermont-Ferrand, F-63000 Clermont-Ferrand, France; (C.E.K.); (C.A.-D.); (M.A.)
| | - Maria Gutierrez-Mecinas
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QQ, UK; (M.G.-M.); (A.J.T.)
| | - Andrew J. Todd
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QQ, UK; (M.G.-M.); (A.J.T.)
| | - Alain Artola
- Neuro-Dol, Inserm, Université Clermont Auvergne, CHU Clermont-Ferrand, F-63000 Clermont-Ferrand, France; (C.E.K.); (C.A.-D.); (M.A.)
- Correspondence: (A.A.); (R.D.)
| | - Radhouane Dallel
- Neuro-Dol, Inserm, Université Clermont Auvergne, CHU Clermont-Ferrand, F-63000 Clermont-Ferrand, France; (C.E.K.); (C.A.-D.); (M.A.)
- Correspondence: (A.A.); (R.D.)
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42
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Medlock L, Sekiguchi K, Hong S, Dura-Bernal S, Lytton WW, Prescott SA. Multiscale Computer Model of the Spinal Dorsal Horn Reveals Changes in Network Processing Associated with Chronic Pain. J Neurosci 2022; 42:3133-3149. [PMID: 35232767 PMCID: PMC8996343 DOI: 10.1523/jneurosci.1199-21.2022] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 02/17/2022] [Accepted: 02/17/2022] [Indexed: 11/21/2022] Open
Abstract
Pain-related sensory input is processed in the spinal dorsal horn (SDH) before being relayed to the brain. That processing profoundly influences whether stimuli are correctly or incorrectly perceived as painful. Significant advances have been made in identifying the types of excitatory and inhibitory neurons that comprise the SDH, and there is some information about how neuron types are connected, but it remains unclear how the overall circuit processes sensory input or how that processing is disrupted under chronic pain conditions. To explore SDH function, we developed a computational model of the circuit that is tightly constrained by experimental data. Our model comprises conductance-based neuron models that reproduce the characteristic firing patterns of spinal neurons. Excitatory and inhibitory neuron populations, defined by their expression of genetic markers, spiking pattern, or morphology, were synaptically connected according to available qualitative data. Using a genetic algorithm, synaptic weights were tuned to reproduce projection neuron firing rates (model output) based on primary afferent firing rates (model input) across a range of mechanical stimulus intensities. Disparate synaptic weight combinations could produce equivalent circuit function, revealing degeneracy that may underlie heterogeneous responses of different circuits to perturbations or pathologic insults. To validate our model, we verified that it responded to the reduction of inhibition (i.e., disinhibition) and ablation of specific neuron types in a manner consistent with experiments. Thus validated, our model offers a valuable resource for interpreting experimental results and testing hypotheses in silico to plan experiments for examining normal and pathologic SDH circuit function.SIGNIFICANCE STATEMENT We developed a multiscale computer model of the posterior part of spinal cord gray matter (spinal dorsal horn), which is involved in perceiving touch and pain. The model reproduces several experimental observations and makes predictions about how specific types of spinal neurons and synapses influence projection neurons that send information to the brain. Misfiring of these projection neurons can produce anomalous sensations associated with chronic pain. Our computer model will not only assist in planning future experiments, but will also be useful for developing new pharmacotherapy for chronic pain disorders, connecting the effect of drugs acting at the molecular scale with emergent properties of neurons and circuits that shape the pain experience.
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Affiliation(s)
- Laura Medlock
- Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada
| | - Kazutaka Sekiguchi
- Drug Developmental Research Laboratory, Shionogi Pharmaceutical Research Center, Toyonaka, Osaka 561-0825, Japan
- State University of New York Downstate Health Science University, Brooklyn, New York 11203
| | - Sungho Hong
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, Okinawa, 904-0495, Japan
| | - Salvador Dura-Bernal
- State University of New York Downstate Health Science University, Brooklyn, New York 11203
- Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962
| | - William W Lytton
- State University of New York Downstate Health Science University, Brooklyn, New York 11203
- Kings County Hospital, Brooklyn, New York 11207
| | - Steven A Prescott
- Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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43
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Bardoni R. Experimental Protocols and Analytical Procedures for Studying Synaptic Transmission in Rodent Spinal Cord Dorsal Horn. Curr Protoc 2022; 2:e409. [PMID: 35435326 DOI: 10.1002/cpz1.409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Synaptic modulation and plasticity are key mechanisms underlying pain transmission in the spinal cord and supra-spinal centers. The study and understanding of these phenomena are fundamental to investigating both acute nociception and maladaptive changes occurring in chronic pain. This article describes experimental protocols and analytical methods utilized in electrophysiological studies to investigate synaptic modulation and plasticity at the first station of somatosensory processing, the spinal cord dorsal horn. Protocols useful for characterizing the nature of synaptic inputs, the site of modulation (pre- versus postsynaptic), and the presence of short-term synaptic plasticity are presented. These methods can be employed to study the physiology of acute nociception, the pathological mechanisms of persistent inflammatory and neuropathic pain, and the pharmacology of receptors and channels involved in pain transmission. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Spinal cord dissection and acute slice preparation Basic Protocol 2: Stimulation of the dorsal root and extracellular recording (compound action potentials and field potentials) Basic Protocol 3: Patch-clamp recording from dorsal horn neurons: action potential firing patterns and evoked synaptic inputs Basic Protocol 4: Analysis of parameters responsible for changes in synaptic efficacy Basic Protocol 5: Recording and analysis of currents mediated by astrocytic glutamate.
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Affiliation(s)
- Rita Bardoni
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Via Campi, Modena, Italy
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44
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Boakye PA, Tang SJ, Smith PA. Mediators of Neuropathic Pain; Focus on Spinal Microglia, CSF-1, BDNF, CCL21, TNF-α, Wnt Ligands, and Interleukin 1β. FRONTIERS IN PAIN RESEARCH 2022; 2:698157. [PMID: 35295524 PMCID: PMC8915739 DOI: 10.3389/fpain.2021.698157] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 07/14/2021] [Indexed: 01/04/2023] Open
Abstract
Intractable neuropathic pain is a frequent consequence of nerve injury or disease. When peripheral nerves are injured, damaged axons undergo Wallerian degeneration. Schwann cells, mast cells, fibroblasts, keratinocytes and epithelial cells are activated leading to the generation of an “inflammatory soup” containing cytokines, chemokines and growth factors. These primary mediators sensitize sensory nerve endings, attract macrophages, neutrophils and lymphocytes, alter gene expression, promote post-translational modification of proteins, and alter ion channel function in primary afferent neurons. This leads to increased excitability and spontaneous activity and the generation of secondary mediators including colony stimulating factor 1 (CSF-1), chemokine C-C motif ligand 21 (CCL-21), Wnt3a, and Wnt5a. Release of these mediators from primary afferent neurons alters the properties of spinal microglial cells causing them to release tertiary mediators, in many situations via ATP-dependent mechanisms. Tertiary mediators such as BDNF, tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and other Wnt ligands facilitate the generation and transmission of nociceptive information by increasing excitatory glutamatergic transmission and attenuating inhibitory GABA and glycinergic transmission in the spinal dorsal horn. This review focusses on activation of microglia by secondary mediators, release of tertiary mediators from microglia and a description of their actions in the spinal dorsal horn. Attention is drawn to the substantial differences in the precise roles of various mediators in males compared to females. At least 25 different mediators have been identified but the similarity of their actions at sensory nerve endings, in the dorsal root ganglia and in the spinal cord means there is considerable redundancy in the available mechanisms. Despite this, behavioral studies show that interruption of the actions of any single mediator can relieve signs of pain in experimental animals. We draw attention this paradox. It is difficult to explain how inactivation of one mediator can relieve pain when so many parallel pathways are available.
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Affiliation(s)
- Paul A Boakye
- Department of Anesthesiology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Shao-Jun Tang
- Department of Anesthesiology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Peter A Smith
- Neuroscience and Mental Health Institute and Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
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45
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Paulsen RT, Burrell BD. Activity-Dependent Modulation of Tonic GABA Currents by Endocannabinoids in Hirudo verbana. Front Synaptic Neurosci 2022; 14:760330. [PMID: 35368247 PMCID: PMC8964407 DOI: 10.3389/fnsyn.2022.760330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 02/21/2022] [Indexed: 01/21/2023] Open
Abstract
Endocannabinoids are lipid neuromodulators that are synthesized on demand and primarily signal in a retrograde manner to elicit depression of excitatory and inhibitory synapses. Despite the considerable interest in their potential analgesic effects, there is evidence that endocannabinoids can have both pro-nociceptive and anti-nociceptive effects. The mechanisms contributing to the opposing effects of endocannabinoids in nociception need to be better understood before cannabinoid-based therapies can be effectively utilized to treat pain. Using the medicinal leech, Hirudo verbana, this work investigates whether endocannabinoids modulate tonic inhibition onto non-nociceptive afferents. In voltage clamp recordings, we analyzed changes in the tonic inhibition in pressure-sensitive (P) cells following pre-treatment with endocannabinoids, 2-arachidonoylglycerol (2-AG) or anandamide (AEA). We also tested whether high frequency stimulation (HFS) of nociceptive (N) cells could also modulate tonic inhibition. Both endocannabinoid application and N cell HFS depressed tonic inhibition in the P cell. Depression of tonic inhibition by N cell HFS was blocked by SB 366791 (a TRPV1 inhibitor). SB 366791 also prevented 2-AG-and AEA-induced depression of tonic inhibition. HFS-induced depression was not blocked by tetrahydrolipstatin (THL), which prevents 2-AG synthesis, nor AM 251 (a CB1 receptor inverse agonist). These results illustrate a novel activity-dependent modulation of tonic GABA currents that is mediated by endocannabinoid signaling and is likely to play an important role in sensitization of non-nociceptive afferent pathways.
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46
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Jorgensen MM, Burrell BD. Approaches to studying injury-induced sensitization and the potential role of an endocannabinoid transmitter. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2022; 208:313-323. [PMID: 35050393 PMCID: PMC8940709 DOI: 10.1007/s00359-021-01540-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 12/28/2021] [Accepted: 12/30/2021] [Indexed: 10/19/2022]
Abstract
Endocannabinoids are traditionally thought to have an analgesic effect. However, it has been shown that while endocannabinoids can depress nociceptive signaling, they can also enhance non-nociceptive signaling. Therefore, endocannabinoids have the potential to contribute to non-nociceptive sensitization after an injury. Using Hirudo verbana (the medicinal leech), a model of injury-induced sensitization was developed in which a reproducible piercing injury was delivered to the posterior sucker of Hirudo. Injury-induced changes in the non-nociceptive threshold of Hirudo were determined through testing with Von Frey filaments and changes in the response to nociceptive stimuli were tested by measuring the latency to withdraw to a nociceptive thermal stimulus (Hargreaves apparatus). To test the potential role of endocannabinoids in mediating injury-induced sensitization, animals were injected with tetrahydrolipstatin (THL), which inhibits synthesis of the endocannabinoid transmitter 2-arachidonoylglycerol (2-AG). Following injury, a significant decrease in the non-nociceptive response threshold (consistent with non-nociceptive sensitization) and a significant decrease in the response latency to nociceptive stimulation (consistent with nociceptive sensitization) were observed. In animals injected with THL, a decrease in non-nociceptive sensitization in injured animals was observed, but no effect on nociceptive sensitization was observed.
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47
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Fan W, Sullivan SJ, Sdrulla AD. Dorsal Column and Root Stimulation at Aβ-fiber Intensity Activate Superficial Dorsal Horn Glutamatergic and GABAergic Populations. Mol Pain 2022; 18:17448069221079559. [PMID: 35088625 PMCID: PMC8891844 DOI: 10.1177/17448069221079559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Neurostimulation therapies are frequently used in patients with chronic pain conditions. They emerged from Gate Control Theory (GCT), which posits that Aβ-fiber activation recruits superficial dorsal horn (SDH) inhibitory networks to “close the gate” on nociceptive transmission, resulting in pain relief. However, the efficacy of current therapies is limited, and the underlying circuits remain poorly understood. For example, it remains unknown whether ongoing stimulation of Aβ-fibers is sufficient to drive activity in SDH neurons. We used multiphoton microscopy in spinal cords extracted from mice expressing the genetically encoded calcium indicator GCaMP6s in glutamatergic and GABAergic populations; activity levels were inferred from deconvolved calcium signals using CaImAn software. Sustained Aβ-fiber stimulation at the dorsal columns or dorsal roots drove robust yet transient activation of both SDH populations. Following the initial increase, activity levels decreased below baseline in glutamatergic neurons and were depressed after stimulation ceased in both populations. Surprisingly, only about half of GABAergic neurons responded to Aβ-fiber stimulation. This subset showed elevated activity for the entire duration of stimulation, while non-responders decreased with time. Our findings suggest that Aβ-fiber stimulation initially recruits both excitatory and inhibitory populations but has divergent effects on their activity, providing a foundation for understanding the analgesic effects of neurostimulation devices. Perspective: This article used microscopy to characterize the responses of mouse spinal cord cells to stimulation of non-painful nerve fibers. These findings deepen our understanding of how the spinal cord processes information and provide a foundation for improving pain-relieving therapies.
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Affiliation(s)
- Wei Fan
- Anesthesiology and Pain Management6684Oregon Health & Science University
| | - Steve J Sullivan
- Anesthesiology and Pain Management6684Oregon Health & Science University
| | - Andrei D Sdrulla
- Anesthesiology and Pain Management6684Oregon Health & Science University
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48
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Yang NJ, Isensee J, Neel DV, Quadros AU, Zhang HXB, Lauzadis J, Liu SM, Shiers S, Belu A, Palan S, Marlin S, Maignel J, Kennedy-Curran A, Tong VS, Moayeri M, Röderer P, Nitzsche A, Lu M, Pentelute BL, Brüstle O, Tripathi V, Foster KA, Price TJ, Collier RJ, Leppla SH, Puopolo M, Bean BP, Cunha TM, Hucho T, Chiu IM. Anthrax toxins regulate pain signaling and can deliver molecular cargoes into ANTXR2 + DRG sensory neurons. Nat Neurosci 2021; 25:168-179. [PMID: 34931070 DOI: 10.1038/s41593-021-00973-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 11/01/2021] [Indexed: 11/09/2022]
Abstract
Bacterial products can act on neurons to alter signaling and function. In the present study, we found that dorsal root ganglion (DRG) sensory neurons are enriched for ANTXR2, the high-affinity receptor for anthrax toxins. Anthrax toxins are composed of protective antigen (PA), which binds to ANTXR2, and the protein cargoes edema factor (EF) and lethal factor (LF). Intrathecal administration of edema toxin (ET (PA + EF)) targeted DRG neurons and induced analgesia in mice. ET inhibited mechanical and thermal sensation, and pain caused by formalin, carrageenan or nerve injury. Analgesia depended on ANTXR2 expressed by Nav1.8+ or Advillin+ neurons. ET modulated protein kinase A signaling in mouse sensory and human induced pluripotent stem cell-derived sensory neurons, and attenuated spinal cord neurotransmission. We further engineered anthrax toxins to introduce exogenous protein cargoes, including botulinum toxin, into DRG neurons to silence pain. Our study highlights interactions between a bacterial toxin and nociceptors, which may lead to the development of new pain therapeutics.
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Affiliation(s)
- Nicole J Yang
- Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - Jörg Isensee
- Translational Pain Research, Department of Anesthesiology and Intensive Care Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Dylan V Neel
- Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - Andreza U Quadros
- Center for Research in Inflammatory Diseases, Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | | | - Justas Lauzadis
- Department of Anesthesiology, Stony Brook Medicine, Stony Brook, NY, USA
| | | | - Stephanie Shiers
- Department of Neuroscience, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, USA
| | - Andreea Belu
- Translational Pain Research, Department of Anesthesiology and Intensive Care Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | | | | | | | | | - Victoria S Tong
- Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Pascal Röderer
- Institute of Reconstructive Neurobiology, University of Bonn Medical Faculty and University Hospital Bonn, Bonn, Germany.,Cellomics Unit, LIFE & BRAIN GmbH, Bonn, Germany
| | - Anja Nitzsche
- Institute of Reconstructive Neurobiology, University of Bonn Medical Faculty and University Hospital Bonn, Bonn, Germany.,Cellomics Unit, LIFE & BRAIN GmbH, Bonn, Germany
| | - Mike Lu
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Bradley L Pentelute
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA.,The Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Oliver Brüstle
- Institute of Reconstructive Neurobiology, University of Bonn Medical Faculty and University Hospital Bonn, Bonn, Germany
| | | | | | - Theodore J Price
- Department of Neuroscience, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, USA
| | - R John Collier
- Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Michelino Puopolo
- Department of Anesthesiology, Stony Brook Medicine, Stony Brook, NY, USA
| | - Bruce P Bean
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Thiago M Cunha
- Center for Research in Inflammatory Diseases, Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Tim Hucho
- Translational Pain Research, Department of Anesthesiology and Intensive Care Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Isaac M Chiu
- Department of Immunology, Harvard Medical School, Boston, MA, USA.
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49
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Kearns A, Jayasi J, Liu X, Wang J, Shi Y, Chung JM, La JH, Tang SJ, Bae C. Neuron Type-Dependent Synaptic Activity in the Spinal Dorsal Horn of Opioid-Induced Hyperalgesia Mouse Model. Front Synaptic Neurosci 2021; 13:748929. [PMID: 34867259 PMCID: PMC8637419 DOI: 10.3389/fnsyn.2021.748929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/26/2021] [Indexed: 11/26/2022] Open
Abstract
Opioids are widely used for pain relief; however, chronic opioid use causes a paradoxical state of enhanced pain sensitivity, termed “Opioid-induced hyperalgesia (OIH).” Despite the clinical importance of OIH, the detailed mechanism by which it enhances pain sensitivity remains unclear. In this study, we tested whether repeated morphine induces a neuronal circuit polarization in the mouse spinal dorsal horn (SDH). Transgenic mice expressing GFP to neurokinin 1 receptor-expressing neurons (sNK1Rn) and GABAergic interneurons (sGABAn) that received morphine [20 mg/kg, once daily for four consecutive days (i.p.)] developed mechanical hypersensitivity. Repeated morphine altered synaptic strengths in the SDH as a specific cell-type but not in a gender-dependent manner. In sNK1Rn and non-tonic firing neurons, repeated morphine treatment significantly increased frequency of spontaneous excitatory postsynaptic current (sEPSC) and evoked EPSC (eEPSC). In addition, repeated morphine treatment significantly decreased evoked inhibitory postsynaptic current (eIPSC) in sNK1Rn. Conversely, in sGABAn and tonic firing neurons, repeated morphine treatment significantly decreased sEPSC frequency and eEPSC, but had no change of eIPSC in sGABAn. Interestingly, repeated morphine treatment significantly decreased neuronal rheobase of sNK1Rn but had no effect on sGABAn. These findings suggest that spinal neuronal circuit polarization maybe the mechanism of OIH and identify a potential therapeutic mechanism to prevent or treat opioid-induced pain.
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Affiliation(s)
- Austin Kearns
- School of Electrical, Computer, and Biomedical Engineering, Southern Illinois University, Carbondale, IL, United States
| | - Jazmine Jayasi
- School of Electrical, Computer, and Biomedical Engineering, Southern Illinois University, Carbondale, IL, United States
| | - Xin Liu
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Jigong Wang
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Yuqiang Shi
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Jin Mo Chung
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Jun-Ho La
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Shao-Jun Tang
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Chilman Bae
- School of Electrical, Computer, and Biomedical Engineering, Southern Illinois University, Carbondale, IL, United States.,Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
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50
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Delgado‐Lezama R, Bravo‐Hernández M, Franco‐Enzástiga Ú, De la Luz‐Cuellar YE, Alvarado‐Cervantes NS, Raya‐Tafolla G, Martínez‐Zaldivar LA, Vargas‐Parada A, Rodríguez‐Palma EJ, Vidal‐Cantú GC, Guzmán‐Priego CG, Torres‐López JE, Murbartián J, Felix R, Granados‐Soto V. The role of spinal cord extrasynaptic α 5 GABA A receptors in chronic pain. Physiol Rep 2021; 9:e14984. [PMID: 34409771 PMCID: PMC8374381 DOI: 10.14814/phy2.14984] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 06/25/2021] [Accepted: 06/29/2021] [Indexed: 11/24/2022] Open
Abstract
Chronic pain is an incapacitating condition that affects a large population worldwide. Until now, there is no drug treatment to relieve it. The impairment of GABAergic inhibition mediated by GABAA receptors (GABAA R) is considered a relevant factor in mediating chronic pain. Even though both synaptic and extrasynaptic GABAA inhibition are present in neurons that process nociceptive information, the latter is not considered relevant as a target for the development of pain treatments. In particular, the extrasynaptic α5 GABAA Rs are expressed in laminae I-II of the spinal cord neurons, sensory neurons, and motoneurons. In this review, we discuss evidence showing that blockade of the extrasynaptic α5 GABAA Rs reduces mechanical allodynia in various models of chronic pain and restores the associated loss of rate-dependent depression of the Hoffmann reflex. Furthermore, in healthy animals, extrasynaptic α5 GABAA R blockade induces both allodynia and hyperalgesia. These results indicate that this receptor may have an antinociceptive and pronociceptive role in healthy and chronic pain-affected animals, respectively. We propose a hypothesis to explain the relevant role of the extrasynaptic α5 GABAA Rs in the processing of nociceptive information. The data discussed here strongly suggest that this receptor could be a valid pharmacological target to treat chronic pain states.
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Affiliation(s)
| | - Mariana Bravo‐Hernández
- Neuroregeneration LaboratoryDepartment of AnesthesiologyUniversity of CaliforniaSan Diego, La JollaCAUSA
| | | | | | | | | | | | | | | | | | - Crystell G. Guzmán‐Priego
- Mechanisms of Pain LaboratoryDivisión Académica de Ciencias de la SaludUniversidad Juárez Autónoma de Tabasco, VillahermosaTabascoMexico
| | - Jorge E. Torres‐López
- Mechanisms of Pain LaboratoryDivisión Académica de Ciencias de la SaludUniversidad Juárez Autónoma de Tabasco, VillahermosaTabascoMexico
- Hospital Regional de Alta Especialidad “Dr. Juan Graham Casasús”, VillahermosaTabascoMexico
| | | | - Ricardo Felix
- Departamento de Biología CelularCinvestavMexico CityMexico
| | - Vinicio Granados‐Soto
- Neurobiology of Pain LaboratoryDepartamento de FarmacobiologíaCinvestavMexico CityMexico
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