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Chen HH, Mohsin M, Ge JY, Feng YT, Wang JG, Ou YS, Jiang ZJ, Hu BY, Liu XJ. Optogenetic Activation of Peripheral Somatosensory Neurons in Transgenic Mice as a Neuropathic Pain Model for Assessing the Therapeutic Efficacy of Analgesics. ACS Pharmacol Transl Sci 2024; 7:236-248. [PMID: 38230281 PMCID: PMC10789130 DOI: 10.1021/acsptsci.3c00254] [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: 09/27/2023] [Revised: 11/17/2023] [Accepted: 11/20/2023] [Indexed: 01/18/2024]
Abstract
Optogenetics is a novel biotechnology widely used to precisely manipulate a specific peripheral sensory neuron or neural circuit. However, the use of optogenetics to assess the therapeutic efficacy of analgesics is elusive. In this study, we generated a transgenic mouse stain in which all primary somatosensory neurons can be optogenetically activated to mimic neuronal hyperactivation in the neuropathic pain state for the assessment of analgesic effects of drugs. A transgenic mouse was generated using the advillin-Cre line mated with the Ai32 strain, in which channelrhodopsin-2 fused to enhanced yellow fluorescence protein (ChR2-EYFP) was conditionally expressed in all types of primary somatosensory neurons (advillincre/ChR2+/+). Immunofluorescence and transdermal photostimulation on the hindpaws were used to verify the transgenic mice. Optical stimulation to evoke pain-like paw withdrawal latency was used to assess the analgesic effects of a series of drugs. Injury- and pain-related molecular biomarkers were investigated with immunohistofluorescence. We found that the expression of ChR2-EYFP was observed in many primary afferents of paw skin and sciatic nerves and in primary sensory neurons and laminae I and II of the spinal dorsal horns in advillincre/ChR2+/+ mice. Transdermal blue light stimulation of the transgenic mouse hindpaw evoked nocifensive paw withdrawal behavior. Treatment with gabapentin, some channel blockers, and local anesthetics, but not opioids or COX-1/2 inhibitors, prolonged the paw withdrawal latency in the transgenic mice. The analgesic effect of gabapentin was also verified by the decreased expression of injury- and pain-related molecular biomarkers. These optogenetic mice provide a promising model for assessing the therapeutic efficacy of analgesics in neuropathic pain.
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Affiliation(s)
- Hao-Hao Chen
- School
of Pharmacy, Nantong University, Nantong, Jiangsu Province 226001, China
- Pain
and Related Diseases Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province 515041, China
| | - Muhammad Mohsin
- Pain
and Related Diseases Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province 515041, China
| | - Jia-Yi Ge
- School
of Pharmacy, Nantong University, Nantong, Jiangsu Province 226001, China
| | - Yu-Ting Feng
- School
of Pharmacy, Nantong University, Nantong, Jiangsu Province 226001, China
| | - Jing-Ge Wang
- School
of Pharmacy, Nantong University, Nantong, Jiangsu Province 226001, China
| | - Yu-Sen Ou
- Pain
and Related Diseases Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province 515041, China
| | - Zuo-Jie Jiang
- Pain
and Related Diseases Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province 515041, China
| | - Bo-Ya Hu
- Pain
and Related Diseases Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province 515041, China
| | - Xing-Jun Liu
- School
of Pharmacy, Nantong University, Nantong, Jiangsu Province 226001, China
- Pain
and Related Diseases Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province 515041, China
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2
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Espinosa-Juárez JV, Chiquete E, Estañol B, Aceves JDJ. Optogenetic and Chemogenic Control of Pain Signaling: Molecular Markers. Int J Mol Sci 2023; 24:10220. [PMID: 37373365 DOI: 10.3390/ijms241210220] [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: 04/11/2023] [Revised: 06/05/2023] [Accepted: 06/10/2023] [Indexed: 06/29/2023] Open
Abstract
Pain is a complex experience that involves physical, emotional, and cognitive aspects. This review focuses specifically on the physiological processes underlying pain perception, with a particular emphasis on the various types of sensory neurons involved in transmitting pain signals to the central nervous system. Recent advances in techniques like optogenetics and chemogenetics have allowed researchers to selectively activate or inactivate specific neuronal circuits, offering a promising avenue for developing more effective pain management strategies. The article delves into the molecular targets of different types of sensory fibers such as channels, for example, TRPV1 in C-peptidergic fiber, TRPA1 in C-non-peptidergic receptors expressed differentially as MOR and DOR, and transcription factors, and their colocalization with the vesicular transporter of glutamate, which enable researchers to identify specific subtypes of neurons within the pain pathway and allows for selective transfection and expression of opsins to modulate their activity.
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Affiliation(s)
- Josue Vidal Espinosa-Juárez
- Escuela de Ciencias Químicas Sede Ocozocoautla, Universidad Autónoma de Chiapas, Ocozocoautla de Espinosa 29140, Mexico
| | - Erwin Chiquete
- Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City 14080, Mexico
| | - Bruno Estañol
- Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City 14080, Mexico
| | - José de Jesús Aceves
- Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City 14080, Mexico
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Wang M, Gu Y, Meng S, Kang L, Yang J, Sun D, Liu Y, Wan Z, Shan Y, Xue D, Su C, Li S, Yan R, Liu Y, Zhao Y, Pan Y. Association between TRP channels and glutamatergic synapse gene polymorphisms and migraine and the comorbidities anxiety and depression in a Chinese population. Front Genet 2023; 14:1158028. [PMID: 37303955 PMCID: PMC10250607 DOI: 10.3389/fgene.2023.1158028] [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: 02/03/2023] [Accepted: 05/17/2023] [Indexed: 06/13/2023] Open
Abstract
Background: Genetic and environmental factors contribute to migraine and the comorbidities of anxiety and depression. However, the association between genetic polymorphisms in the transient receptor potential (TRP) channels and glutamatergic synapse genes with the risk of migraine and the comorbidities of anxiety and depression remain unclear. Methods: 251 migraine patients containing 49 comorbidities with anxiety and 112 with depression and 600 controls were recruited. A customized 48-plex SNPscan kit was used for genotyping 13 SNPs of nine target genes. Logistic regression was conducted to analyze these SNPs' association with the susceptibility of migraine and comorbidities. The generalized multifactor dimension reduction (GMDR) was applied to analyze the SNP-SNP and gene-environment interactions. The GTEx database was used to examine the effects of the significant SNPs on gene expressions. Results: The TRPV1 rs8065080 and TRPV3 rs7217270 were associated with an increased risk of migraine in the dominant model [ORadj (95% CI): 1.75 (1.09-2.90), p = 0.025; 1.63 (1.02-2.58), p = 0.039, respectively]. GRIK2 rs2227283 was associated with migraine in the edge of significance [ORadj (95% CI) = 1.36 (0.99-1.89), p = 0.062]. In migraine patients, TRPV1 rs222741 was associated with both anxiety risk and depression risk in the recessive model [ORadj (95% CI): 2.64 (1.24-5.73), p = 0.012; 1.97 (1.02-3.85), p = 0.046, respectively]. TRPM8 rs7577262 was associated with anxiety (ORadj = 0.27, 95% CI = 0.10-0.76, p = 0.011). TRPV4 rs3742037, TRPM8 rs17862920 and SLC17A8 rs11110359 were associated with depression in dominant model [ORadj (95% CI): 2.03 (1.06-3.96), p = 0.035; 0.48 (0.23-0.96), p = 0.042; 0.42 (0.20-0.84), p = 0.016, respectively]. Significant eQTL and sQTL signals were observed for SNP rs8065080. Individuals with GRS (Genetic risk scores) of Q4 (14-17) had a higher risk of migraine and a lower risk of comorbidity anxiety than those with Genetic risk scores scores of Q1 (0-9) groups [ORadj (95% CI): 2.31 (1.39-3.86), p = 0.001; 0.28 (0.08-0.88), p = 0.034, respectively]. Conclusion: This study suggests that TRPV1 rs8065080, TRPV3 rs7217270, and GRIK2 rs2227283 polymorphism may associate with migraine risk. TRPV1 rs222741 and TRPM8 rs7577262 may associate with migraine comorbidity anxiety risk. rs222741, rs3742037, rs17862920, and rs11110359 may associate with migraine comorbidity depression risk. Higher GRS scores may increase migraine risk and decrease comorbidity anxiety risk.
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Affiliation(s)
- Mingxue Wang
- Department of Epidemiology, School of Public Health, Harbin Medical University, Harbin, China
| | - Yujia Gu
- Chronic Disease Prevention and Treatment Clinic, Heilongjiang Provincial Center for Disease Control and Prevention, Harbin, China
| | - Shuhan Meng
- Department of Epidemiology, School of Public Health, Harbin Medical University, Harbin, China
| | - Lixin Kang
- Department of Epidemiology, School of Public Health, Harbin Medical University, Harbin, China
| | - Jing Yang
- Department of Neurology, Beidahuang Group Hongxinglong Hospital, Shuangyashan, China
| | - Degang Sun
- Department of Neurology, Beidahuang Group Hongxinglong Hospital, Shuangyashan, China
| | - Yuxing Liu
- Catheterization Room, Beidahuang Group Hongxinglong Hospital, Shuangyashan, China
| | - Ze Wan
- Science and Education Section, Beidahuang Group Hongxinglong Hospital, Shuangyashan, China
| | - Yi Shan
- Physical Examination Section, Beidahuang Group Baoquanling Hospital, Hegang, China
| | - Dongjie Xue
- Department of Neurology, Hegang He Mine Hospital, Hegang, China
| | - Chang Su
- Department of Internal Medicine, Baoquanling Farm Hospital, Hegang, China
| | - Shufen Li
- Vaccination Clinic, Baoquanling Farm Hospital, Hegang, China
| | - Ran Yan
- Department of Epidemiology, School of Public Health, Harbin Medical University, Harbin, China
| | - Yu Liu
- Chronic Disease Prevention and Treatment Clinic, Heilongjiang Provincial Center for Disease Control and Prevention, Harbin, China
| | - Yashuang Zhao
- Department of Epidemiology, School of Public Health, Harbin Medical University, Harbin, China
| | - Yonghui Pan
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
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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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5
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de Almeida C, Chabbah N, Eyraud C, Fasano C, Bernard V, Pietrancosta N, Fabre V, El Mestikawy S, Daumas S. Absence of VGLUT3 Expression Leads to Impaired Fear Memory in Mice. eNeuro 2023; 10:ENEURO.0304-22.2023. [PMID: 36720646 PMCID: PMC9953049 DOI: 10.1523/eneuro.0304-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 01/08/2023] [Accepted: 01/10/2023] [Indexed: 02/02/2023] Open
Abstract
Fear is an emotional mechanism that helps to cope with potential hazards. However, when fear is generalized, it becomes maladaptive and represents a core symptom of posttraumatic stress disorder (PTSD). Converging lines of research show that dysfunction of glutamatergic neurotransmission is a cardinal feature of trauma and stress related disorders such as PTSD. However, the involvement of glutamatergic co-transmission in fear is less well understood. Glutamate is accumulated into synaptic vesicles by vesicular glutamate transporters (VGLUTs). The atypical subtype, VGLUT3, is responsible for the co-transmission of glutamate with acetylcholine, serotonin, or GABA. To understand the involvement of VGLUT3-dependent co-transmission in aversive memories, we used a Pavlovian fear conditioning paradigm in VGLUT3-/- mice. Our results revealed a higher contextual fear memory in these mice, despite a facilitation of extinction. In addition, the absence of VGLUT3 leads to fear generalization, probably because of a pattern separation deficit. Our study suggests that the VGLUT3 network plays a crucial role in regulating emotional memories. Hence, VGLUT3 is a key player in the processing of aversive memories and therefore a potential therapeutic target in stress-related disorders.
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Affiliation(s)
- Camille de Almeida
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris 75005, France
| | - Nida Chabbah
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris 75005, France
| | - Camille Eyraud
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris 75005, France
| | - Caroline Fasano
- Douglas Mental Health University Institute, Department of Psychiatry, McGill University, Montréal QC H4H 1R3, Quebec, Canada
| | - Véronique Bernard
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris 75005, France
| | - Nicolas Pietrancosta
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris 75005, France
| | - Véronique Fabre
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris 75005, France
| | - Salah El Mestikawy
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris 75005, France
- Douglas Mental Health University Institute, Department of Psychiatry, McGill University, Montréal QC H4H 1R3, Quebec, Canada
| | - Stephanie Daumas
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris 75005, France
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6
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Hogri R, Baltov B, Drdla-Schutting R, Mussetto V, Raphael H, Trofimova L, Sandkühler J. Probing pain aversion in rats with the "Heat Escape Threshold" paradigm. Mol Pain 2023; 19:17448069231156657. [PMID: 36717755 PMCID: PMC9996743 DOI: 10.1177/17448069231156657] [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] [Indexed: 02/01/2023] Open
Abstract
The aversive aspect of pain constitutes a major burden faced by pain patients. This has been recognized by the pain research community, leading to the development of novel methods focusing on affective-motivational behaviour in pain model animals. The most common tests used to assess pain aversion in animals require cognitive processes, such as associative learning, complicating the interpretation of results. To overcome this issue, studies in recent years have utilized unconditioned escape as a measure of aversion. However, the vast majority of these studies quantify jumping - a common escape behaviour in mice, but not in adult rats, thus limiting its use. Here, we present the "Heat Escape Threshold" (HET) paradigm for assessing heat aversion in rats. We demonstrate that this method can robustly and reproducibly detect the localized effects of an inflammatory pain model (intraplantar carrageenan) in male and female Sprague-Dawley rats. In males, a temperature that evoked unconditioned escape following carrageenan treatment also induced real-time place avoidance (RTPA). Systemic morphine more potently alleviated carrageenan-induced heat aversion (as measured by the HET and RTPA methods), as compared to reflexive responses to heat (as measured by the Hargreaves test), supporting previous findings. Next, we examined how blocking of excitatory transmission to the lateral parabrachial nucleus (LPBN), a key node in the ascending pain system, affects pain behaviour. Using the HET and Hargreaves tests, we show that intra-LPBN application of glutamate antagonists reverses the effects of carrageenan on both affective and reflexive pain behaviour, respectively. Finally, we employed the HET paradigm in a generalized opioid-withdrawal pain model. Withdrawal from a brief systemic administration of remifentanil resulted in a long-lasting and robust increase in heat aversion, but no change in reflexive responses to heat. Taken together, these data demonstrate the utility of the HET paradigm as a novel tool in preclinical pain research.
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Affiliation(s)
- Roni Hogri
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Bozhidar Baltov
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Ruth Drdla-Schutting
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Valeria Mussetto
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Holzinger Raphael
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Lidia Trofimova
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Jürgen Sandkühler
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
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7
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Finno CJ, Chen Y, Park S, Lee JH, Perez-Flores MC, Choi J, Yamoah EN. Cisplatin Neurotoxicity Targets Specific Subpopulations and K+ Channels in Tyrosine-Hydroxylase Positive Dorsal Root Ganglia Neurons. Front Cell Neurosci 2022; 16:853035. [PMID: 35586548 PMCID: PMC9108181 DOI: 10.3389/fncel.2022.853035] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 03/29/2022] [Indexed: 11/13/2022] Open
Abstract
Among the features of cisplatin chemotherapy-induced peripheral neuropathy are chronic pain and innocuous mechanical hypersensitivity. The complete etiology of the latter remains unknown. Here, we show that cisplatin targets a heterogeneous population of tyrosine hydroxylase-positive (TH+) primary afferent dorsal root ganglion neurons (DRGNs) in mice, determined using single-cell transcriptome and electrophysiological analyses. TH+ DRGNs regulate innocuous mechanical sensation through C-low threshold mechanoreceptors. A differential assessment of wild-type and vitamin E deficient TH+ DRGNs revealed heterogeneity and specific functional phenotypes. The TH+ DRGNs comprise; fast-adapting eliciting one action potential (AP; 1-AP), moderately-adapting (≥2-APs), in responses to square-pulse current injection, and spontaneously active (SA). Cisplatin increased the input resistance and AP frequency but reduced the temporal coding feature of 1-AP and ≥2-APs neurons. By contrast, cisplatin has no measurable effect on the SA neurons. Vitamin E reduced the cisplatin-mediated increased excitability but did not improve the TH+ neuron temporal coding properties. Cisplatin mediates its effect by targeting outward K+ current, likely carried through K2P18.1 (Kcnk18), discovered through the differential transcriptome studies and heterologous expression. Studies show a potential new cellular target for chemotherapy-induced peripheral neuropathy and implicate the possible neuroprotective effects of vitamin E in cisplatin chemotherapy.
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Affiliation(s)
- Carrie J. Finno
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
- *Correspondence: Carrie J. Finno,
| | - Yingying Chen
- Department of Physiology and Cell Biology, School of Medicine, University of Reno, Reno, NV, United States
| | - Seojin Park
- Department of Physiology and Cell Biology, School of Medicine, University of Reno, Reno, NV, United States
| | - Jeong Han Lee
- Department of Physiology and Cell Biology, School of Medicine, University of Reno, Reno, NV, United States
| | | | - Jinsil Choi
- Department of Physiology and Cell Biology, School of Medicine, University of Reno, Reno, NV, United States
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Reno, Reno, NV, United States
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8
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Larsson M, Nagi SS. Role of C-tactile fibers in pain modulation: animal and human perspectives. Curr Opin Behav Sci 2022. [DOI: 10.1016/j.cobeha.2021.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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9
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Mecum NE, Russell R, Lee J, Sullivan C, Meng ID. Optogenetic Inhibition of Nav1.8 Expressing Corneal Afferents Reduces Persistent Dry Eye Pain. Invest Ophthalmol Vis Sci 2021; 62:15. [PMID: 34787642 PMCID: PMC8606841 DOI: 10.1167/iovs.62.14.15] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The aim of the present study was to investigate the contribution of Nav1.8 expressing corneal afferent neurons to the presence of ongoing pain in lacrimal gland excision (LGE)-induced dry eye. Methods The proton pump archaerhodopsin-3/eGFP (ArchT/eGFP) was conditionally expressed in corneal afferents using Nav1.8-cre mice. Dry eye was produced by unilateral LGE. Real time place preference was assessed using a three-chamber apparatus. A neutral, unlit center chamber was flanked by one illuminated with a control light and one illuminated with an ArchT activating light. For real-time preference, animals were placed in the neutral chamber and tracked over five 10-minute sessions, with the lights turned on during the second and fourth sessions. In other studies, movement was tracked over three 10-minute sessions (the lights turned on only during the second session), with animals tested once per day over the course of 4 days. A local anesthetic was used to examine the role of ongoing corneal afferent activity in producing place preference. Results The corneal afferent nerves and trigeminal ganglion cell bodies showed a robust eGFP signal in Nav1.8-cre;ArchT/eGFP mice. After LGE, Nav1.8-cre;ArchT/eGFP mice demonstrated a preference for the ArchT activating light paired chamber. Preference was prevented with pre-application to the cornea of a local anesthetic. Nav1.8-cre;ArchT/eGFP mice with sham surgery and LGE wild-type control mice did not develop preference. Conclusions Results indicate LGE-induced persistent, ongoing pain, driven by Nav1.8 expressing corneal afferents. Inhibition of these neurons represents a potential strategy for treating ongoing dry eye-induced pain.
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Affiliation(s)
- Neal E Mecum
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States.,Molecular and Biomedical Sciences, University of Maine, Orono, Maine, United States
| | - Rachel Russell
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States
| | - Jun Lee
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States.,Department of Complete Denture Prosthodontics, School of Dentistry, Nihon University, Tokyo, Japan
| | - Cara Sullivan
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States.,Graduate Studies in Biomedical Sciences and Engineering, University of Maine, Orono, Maine, United States
| | - Ian D Meng
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States.,Graduate Studies in Biomedical Sciences and Engineering, University of Maine, Orono, Maine, United States.,Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, Maine, United States
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10
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A subset of spinal dorsal horn interneurons crucial for gating touch-evoked pain-like behavior. Proc Natl Acad Sci U S A 2021; 118:2021220118. [PMID: 33431693 DOI: 10.1073/pnas.2021220118] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
A cardinal, intractable symptom of neuropathic pain is mechanical allodynia, pain caused by innocuous stimuli via low-threshold mechanoreceptors such as Aβ fibers. However, the mechanism by which Aβ fiber-derived signals are converted to pain remains incompletely understood. Here we identify a subset of inhibitory interneurons in the spinal dorsal horn (SDH) operated by adeno-associated viral vectors incorporating a neuropeptide Y promoter (AAV-NpyP+) and show that specific ablation or silencing of AAV-NpyP+ SDH interneurons converted touch-sensing Aβ fiber-derived signals to morphine-resistant pain-like behavioral responses. AAV-NpyP+ neurons received excitatory inputs from Aβ fibers and transmitted inhibitory GABA signals to lamina I neurons projecting to the brain. In a model of neuropathic pain developed by peripheral nerve injury, AAV-NpyP+ neurons exhibited deeper resting membrane potentials, and their excitation by Aβ fibers was impaired. Conversely, chemogenetic activation of AAV-NpyP+ neurons in nerve-injured rats reversed Aβ fiber-derived neuropathic pain-like behavior that was shown to be morphine-resistant and reduced pathological neuronal activation of superficial SDH including lamina I. These findings suggest that identified inhibitory SDH interneurons that act as a critical brake on conversion of touch-sensing Aβ fiber signals into pain-like behavioral responses. Thus, enhancing activity of these neurons may offer a novel strategy for treating neuropathic allodynia.
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Abstract
Inhibitory interneurons in the adult spinal dorsal horn (DH) can be neurochemically classified into subpopulations that regulate distinct somatosensory modalities. Although inhibitory networks in the rodent DH undergo dramatic remodeling over the first weeks of life, little is known about the maturation of identified classes of GABAergic interneurons, or whether their role in somatosensation shifts during development. We investigated age-dependent changes in the connectivity and function of prodynorphin (DYN)-lineage neurons in the mouse DH that suppress mechanosensation and itch during adulthood. In vitro patch clamp recordings revealed a developmental increase in primary afferent drive to DYN interneurons and a transition from exclusive C-fiber monosynaptic input to mixed A-fiber and C-fiber innervation. Although most adult DYN interneurons exhibited tonic firing as expected from their inhibitory phenotype, neonatal and adolescent DYN cells were predominantly classified as phasic or single-spiking. Importantly, we also found that most of the inhibitory presynaptic terminals contacting lamina I spinoparabrachial projection neurons (PNs) originate from DYN neurons. Furthermore, inhibitory synaptic input from DYN interneurons onto PNs was weaker during the neonatal period, likely reflecting a lower number of GABAergic terminals and a reduced probability of GABA release compared to adults. Finally, spinal DYN interneurons attenuated mechanical sensitivity throughout development, but this population dampened acute nonhistaminergic itch only during adulthood. Collectively, these findings suggest that the spinal "gates" controlling sensory transmission to the brain may emerge in a modality-selective manner during early life due to the postnatal tuning of inhibitory synaptic circuits within the DH.
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Leveraging VGLUT3 Functions to Untangle Brain Dysfunctions. Trends Pharmacol Sci 2021; 42:475-490. [PMID: 33775453 DOI: 10.1016/j.tips.2021.03.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 03/07/2021] [Accepted: 03/08/2021] [Indexed: 11/21/2022]
Abstract
Vesicular glutamate transporters (VGLUTs) were long thought to be specific markers of glutamatergic excitatory transmission. The discovery, two decades ago, of the atypical VGLUT3 has thoroughly modified this oversimplified view. VGLUT3 is strategically expressed in discrete populations of glutamatergic, cholinergic, serotonergic, and even GABAergic neurons. Recent reports show the subtle, but critical, implications of VGLUT3-dependent glutamate co-transmission and its roles in the regulation of diverse brain functions and dysfunctions. Progress in the neuropharmacology of VGLUT3 could lead to decisive breakthroughs in the treatment of Parkinson's disease (PD), addiction, eating disorders, anxiety, presbycusis, or pain. This review summarizes recent findings on VGLUT3 and its vesicular underpinnings as well as on possible ways to target this atypical transporter for future therapeutic strategies.
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Low-Threshold Mechanosensitive VGLUT3-Lineage Sensory Neurons Mediate Spinal Inhibition of Itch by Touch. J Neurosci 2020; 40:7688-7701. [PMID: 32895292 DOI: 10.1523/jneurosci.0091-20.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 07/07/2020] [Accepted: 07/20/2020] [Indexed: 11/21/2022] Open
Abstract
Innocuous mechanical stimuli, such as rubbing or stroking the skin, relieve itch through the activation of low-threshold mechanoreceptors. However, the mechanisms behind this inhibition remain unknown. We presently investigated whether stroking the skin reduces the responses of superficial dorsal horn neurons to pruritogens in male C57BL/6J mice. Single-unit recordings revealed that neuronal responses to chloroquine were enhanced during skin stroking, and this was followed by suppression of firing below baseline levels after the termination of stroking. Most of these neurons additionally responded to capsaicin. Stroking did not suppress neuronal responses to capsaicin, indicating state-dependent inhibition. Vesicular glutamate transporter 3 (VGLUT3)-lineage sensory nerves compose a subset of low-threshold mechanoreceptors. Stroking-related inhibition of neuronal responses to chloroquine was diminished by optogenetic inhibition of VGLUT3-lineage sensory nerves in male and female Vglut3-cre/NpHR-EYFP mice. Conversely, in male and female Vglut3-cre/ChR2-EYFP mice, optogenetic stimulation of VGLUT3-lineage sensory nerves inhibited firing responses of spinal neurons to pruritogens after the termination of stimulation. This inhibition was nearly abolished by spinal delivery of the κ-opioid receptor antagonist nor-binaltorphimine dihydrochloride, but not the neuropeptide Y receptor Y1 antagonist BMS193885. Optogenetic stimulation of VGLUT3-lineage sensory nerves inhibited pruritogen-evoked scratching without affecting mechanical and thermal pain behaviors. Therefore, VGLUT3-lineage sensory nerves appear to mediate inhibition of itch by tactile stimuli.SIGNIFICANCE STATEMENT Rubbing or stroking the skin is known to relieve itch. We investigated the mechanisms behind touch-evoked inhibition of itch in mice. Stroking the skin reduced the activity of itch-responsive spinal neurons. Optogenetic inhibition of VGLUT3-lineage sensory nerves diminished stroking-evoked inhibition, and optogenetic stimulation of VGLUT3-lineage nerves inhibited pruritogen-evoked firing. Together, our results provide a mechanistic understanding of touch-evoked inhibition of itch.
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14
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Leiguarda C, McCarthy CJ, Casadei M, Lundgren KH, Coronel MF, Trigosso-Venario H, Seal RP, Seroogy KB, Brumovsky PR. Transcript Expression of Vesicular Glutamate Transporters in Rat Dorsal Root Ganglion and Spinal Cord Neurons: Impact of Spinal Blockade during Hindpaw Inflammation. ACS Chem Neurosci 2020; 11:2602-2614. [PMID: 32697906 DOI: 10.1021/acschemneuro.0c00272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Studies in mouse, and to a lesser extent in rat, have revealed the neuroanatomical distribution of vesicular glutamate transporters (VGLUTs) and begun exposing the critical role of VGLUT2 and VGLUT3 in pain transmission. In the present study in rat, we used specific riboprobes to characterize the transcript expression of all three VGLUTs in lumbar dorsal root ganglia (DRGs) and in the thoracolumbar, lumbar, and sacral spinal cord. We show for the first time in rat a very discrete VGLUT3 expression in DRGs and in deep layers of the dorsal horn. We confirm the abundant expression of VGLUT2, in both DRGs and the spinal cord, including presumable motorneurons in the latter. As expected, VGLUT1 was present in many DRG neuron profiles, and in the spinal cord it was mostly localized to neurons in the dorsal nucleus of Clarke. In rats with a 10 day long hindpaw inflammation, increased spinal expression of VGLUT2 transcript was detected by qRT-PCR, and intrathecal administration of the nonselective VGLUT inhibitor Chicago Sky Blue 6B resulted in reduced mechanical and thermal allodynia for up to 24 h. In conclusion, our results provide a collective characterization of VGLUTs in rat DRGs and the spinal cord, demonstrate increased spinal expression of VGLUT2 during chronic peripheral inflammation, and support the use of spinal VGLUT blockade as a strategy for attenuating inflammatory pain.
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Affiliation(s)
- Candelaria Leiguarda
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Austral, Derqui, Pilar B1629AHJ, Buenos Aires, Argentina
| | - Carly J. McCarthy
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Austral, Derqui, Pilar B1629AHJ, Buenos Aires, Argentina
| | - Mailin Casadei
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Austral, Derqui, Pilar B1629AHJ, Buenos Aires, Argentina
| | - Kerstin H. Lundgren
- Department of Neurology, University of Cincinnati, Cincinnati, Ohio 45267, United States
| | - María Florencia Coronel
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Austral, Derqui, Pilar B1629AHJ, Buenos Aires, Argentina
| | - Harry Trigosso-Venario
- Hospital Universitario Austral, Austral University, Pilar B1629AHJ, Buenos Aires, Argentina
| | - Rebecca P. Seal
- Pittsburgh Center for Pain Research, Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Kim B. Seroogy
- Department of Neurology, University of Cincinnati, Cincinnati, Ohio 45267, United States
| | - Pablo R. Brumovsky
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Austral, Derqui, Pilar B1629AHJ, Buenos Aires, Argentina
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15
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Wang XM, Gu P, Saligan L, Iadarola M, Wong SSC, Ti LK, Cheung CW. Dysregulation of EAAT2 and VGLUT2 Spinal Glutamate Transports via Histone Deacetylase 2 (HDAC2) Contributes to Paclitaxel-induced Painful Neuropathy. Mol Cancer Ther 2020; 19:2196-2209. [PMID: 32847971 DOI: 10.1158/1535-7163.mct-20-0006] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 04/24/2020] [Accepted: 08/05/2020] [Indexed: 11/16/2022]
Abstract
Effective treatments for chemotherapy-induced peripheral neuropathy (CIPN) remain unavailable. Given the significance of spinal cord glutamate transporters in neuronal plasticity and central sensitization, this study investigated the role of excitatory amino acid transporter 2 (EAAT2) and vesicular-glutamate transporter 2 (VGLUT2) in the development of paclitaxel-induced painful neuropathy. Paclitaxel (2 mg/kg, i.p., cumulative dose 8 mg/kg) induced long-lasting mechanical allodynia (>28 days) with increased glutamate concentration and decreased EAAT2 expression with no changes in GABA/glycine or VGAT (vesicular GABA transporter) in rat spinal dorsal horn. VGLUT2 expression was upregulated and coexpressed with enhanced synaptophysin, characterizing nociceptive afferent sprouting and new synapse formation of glutamatergic neurons in the spinal cord dorsal horn. HDAC2 and transcription factor YY1 were also upregulated, and their interaction and colocalization were confirmed following paclitaxel treatment using co-immunoprecipitation. Inhibition or knockdown of HDAC2 expression by valproic acid, BRD6688, or HDAC2 siRNA not only attenuated paclitaxel-induced mechanical allodynia but also suppressed HDAC2 upregulation, glutamate accumulation, and the corresponding changes in EAAT2/VGLUT/synaptophysin expression and HDAC2/YY1 interaction. These findings indicate that loss of the balance between glutamate release and reuptake due to dysregulation EAAT2/VGLUT2/synaptophysin cascade in the spinal dorsal horn plays an important role in the development of paclitaxel-induced neuropathic pain. HDAC2/YY1 interaction as a complex appears essential in regulating this pathway, which can potentially be a therapeutic target to relieve CIPN by reversing central sensitization of spinal nociceptive neurons.
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Affiliation(s)
- Xiao-Min Wang
- Laboratory and Clinical Research Institute for Pain, Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China.
| | - Pan Gu
- Laboratory and Clinical Research Institute for Pain, Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China
| | - Leorey Saligan
- National Institute of Nursing Research, Division of Intramural Research, NIH, Bethesda, Maryland
| | - Michael Iadarola
- Anesthesiology Research Laboratories, Department of Perioperative Medicine, Clinical Center, NIH, Bethesda, Maryland
| | - Stanley Sau Ching Wong
- Laboratory and Clinical Research Institute for Pain, Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China.,Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China
| | - Lian Kah Ti
- Department of Anaesthesia, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Chi Wai Cheung
- Laboratory and Clinical Research Institute for Pain, Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China. .,Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China
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Harding EK, Fung SW, Bonin RP. Insights Into Spinal Dorsal Horn Circuit Function and Dysfunction Using Optical Approaches. Front Neural Circuits 2020; 14:31. [PMID: 32595458 PMCID: PMC7303281 DOI: 10.3389/fncir.2020.00031] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 05/01/2020] [Indexed: 12/13/2022] Open
Abstract
Somatosensation encompasses a variety of essential modalities including touch, pressure, proprioception, temperature, pain, and itch. These peripheral sensations are crucial for all types of behaviors, ranging from social interaction to danger avoidance. Somatosensory information is transmitted from primary afferent fibers in the periphery into the central nervous system via the dorsal horn of the spinal cord. The dorsal horn functions as an intermediary processing center for this information, comprising a complex network of excitatory and inhibitory interneurons as well as projection neurons that transmit the processed somatosensory information from the spinal cord to the brain. It is now known that there can be dysfunction within this spinal cord circuitry in pathological pain conditions and that these perturbations contribute to the development and maintenance of pathological pain. However, the complex and heterogeneous network of the spinal dorsal horn has hampered efforts to further elucidate its role in somatosensory processing. Emerging optical techniques promise to illuminate the underlying organization and function of the dorsal horn and provide insights into the role of spinal cord sensory processing in shaping the behavioral response to somatosensory input that we ultimately observe. This review article will focus on recent advances in optogenetics and fluorescence imaging techniques in the spinal cord, encompassing findings from both in vivo and in vitro preparations. We will also discuss the current limitations and difficulties of employing these techniques to interrogate the spinal cord and current practices and approaches to overcome these challenges.
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Affiliation(s)
- Erika K Harding
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Samuel Wanchi Fung
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada
| | - Robert P Bonin
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.,University of Toronto Centre for the Study of Pain, University of Toronto, Toronto, ON, Canada
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Coutens B, Derreumaux C, Labaste F, Minville V, Guiard BP, Moulédous L, Bounes V, Roussin A, Frances B. Efficacy of multimodal analgesic treatment of severe traumatic acute pain in mice pretreated with chronic high dose of buprenorphine inducing mechanical allodynia. Eur J Pharmacol 2020; 875:172884. [PMID: 31870829 DOI: 10.1016/j.ejphar.2019.172884] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 12/17/2019] [Accepted: 12/18/2019] [Indexed: 11/17/2022]
Abstract
Managing severe acute nociceptive pain in buprenorphine-maintained individuals for opioid use disorder management is challenging owing to the high affinity and very slow dissociation of buprenorphine from μ-opioid receptors that hinders the use of full agonist opioid analgesics. In a translational approach, the aim of this study was to use an animal setting to investigate the effects of a chronic high dose of buprenorphine treatment on nociceptive thresholds before and after applying a severe acute nociceptive traumatic surgery stimulus and to screen postoperative pharmacological analgesic strategies. A chronic treatment of mice with a high dose of buprenorphine (BUP HD, 2 × 200 μg/kg/day; i.p.) revealed significant mechanical allodynia. One and two days after having discontinued buprenorphine administration and having induced a severe nociceptive acute pain by a closed tibial fracture, acute administration of morphine at a dose which has analgesic effects in absence of pretreatment (4.5 mg/kg; i.p.), was ineffective to reduce pain in the BUP HD group. However, mimicking multimodal analgesia strategy used in human postoperative context, the combination of morphine (administered at the same dose) with a NMDA receptor antagonist (ketamine) or an NSAID (ketoprofen) produced antinociceptive responses in these animals. The mouse model of closed tibial fracture could be useful to identify analgesic strategies of postoperative pain for patients with chronic exposure to opioids and suffering from hyperalgesia.
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Affiliation(s)
- Basile Coutens
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université Paul Sabatier Toulouse III, CNRS, UPS, 31000, Toulouse, France
| | - Céline Derreumaux
- Pôle Médecine d'Urgence, Hôpital Universitaire de Purpan, Toulouse, 31059, Cedex 9, France
| | - François Labaste
- Hôpital de Rangueil, Centre Hospitalier Universitaire de Toulouse-Rangueil, 31300, Toulouse, France
| | - Vincent Minville
- Pôle Médecine d'Urgence, Hôpital Universitaire de Purpan, Toulouse, 31059, Cedex 9, France
| | - Bruno Pierre Guiard
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université Paul Sabatier Toulouse III, CNRS, UPS, 31000, Toulouse, France.
| | - Lionel Moulédous
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université Paul Sabatier Toulouse III, CNRS, UPS, 31000, Toulouse, France
| | - Vincent Bounes
- Pôle Médecine d'Urgence, Hôpital Universitaire de Purpan, Toulouse, 31059, Cedex 9, France
| | - Anne Roussin
- Equipe de Pharmacoépidémiologie UMR1027, Université Paul Sabatier Toulouse III, 31000, Toulouse, France; Centre d'Addictovigilance, Service de Pharmacologie Médicale et Clinique, Centre Hospitalier Universitaire de Toulouse-Purpan, 31000, Toulouse, France
| | - Bernard Frances
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université Paul Sabatier Toulouse III, CNRS, UPS, 31000, Toulouse, France
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18
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Abstract
The peripheral nervous system (PNS) is highly complicated and heterogenous. Conventional neuromodulatory approaches have revealed numerous essential biological functions of the PNS and provided excellent tools to treat a large variety of human diseases. Yet growing evidence indicated the importance of cell-type-specific neuromodulation in the PNS in not only biological research using animal models but also potential human therapies. Optogenetics is a recently developed neuromodulatory approach combining optics and genetics that can effectively stimulate or silence neuronal activity with high spatial and temporal precision. Here, I review research regarding optogenetic manipulations for cell-type-specific control of the PNS, highlighting the advantages and challenges of current optogenetic tools, and discuss their potential future applications.
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Affiliation(s)
- Rui B Chang
- Department of Neuroscience, Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06520
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19
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Sen MK, Mahns DA, Coorssen JR, Shortland PJ. Behavioural phenotypes in the cuprizone model of central nervous system demyelination. Neurosci Biobehav Rev 2019; 107:23-46. [PMID: 31442519 DOI: 10.1016/j.neubiorev.2019.08.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 08/01/2019] [Accepted: 08/12/2019] [Indexed: 12/14/2022]
Abstract
The feeding of cuprizone (CPZ) to animals has been extensively used to model the processes of demyelination and remyelination, with many papers adopting a narrative linked to demyelinating conditions like multiple sclerosis (MS), the aetiology of which is unknown. However, no current animal model faithfully replicates the myriad of symptoms seen in the clinical condition of MS. CPZ ingestion causes mitochondrial and endoplasmic reticulum stress and subsequent apoptosis of oligodendrocytes leads to central nervous system demyelination and glial cell activation. Although there are a wide variety of behavioural tests available for characterizing the functional deficits in animal models of disease, including that of CPZ-induced deficits, they have focused on a narrow subset of outcomes such as motor performance, cognition, and anxiety. The literature has not been systematically reviewed in relation to these or other symptoms associated with clinical MS. This paper reviews these tests and makes recommendations as to which are the most important in order to better understand the role of this model in examining aspects of demyelinating diseases like MS.
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Affiliation(s)
- Monokesh K Sen
- School of Medicine, Western Sydney University, New South Wales, Australia
| | - David A Mahns
- School of Medicine, Western Sydney University, New South Wales, Australia
| | - Jens R Coorssen
- Departments of Health Sciences and Biological Sciences, Faculties of Applied Health Sciences and Mathematics & Science, Brock University, Ontario, Canada.
| | - Peter J Shortland
- Science and Health, Western Sydney University, New South Wales, Australia.
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Tetrodotoxin-Sensitive Sodium Channels Mediate Action Potential Firing and Excitability in Menthol-Sensitive Vglut3-Lineage Sensory Neurons. J Neurosci 2019; 39:7086-7101. [PMID: 31300524 DOI: 10.1523/jneurosci.2817-18.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 06/04/2019] [Accepted: 07/03/2019] [Indexed: 12/16/2022] Open
Abstract
Small-diameter vesicular glutamate transporter 3-lineage (Vglut3lineage) dorsal root ganglion (DRG) neurons play an important role in mechanosensation and thermal hypersensitivity; however, little is known about their intrinsic electrical properties. We therefore set out to investigate mechanisms of excitability within this population. Calcium microfluorimetry analysis of male and female mouse DRG neurons demonstrated that the cooling compound menthol selectively activates a subset of Vglut3lineage neurons. Whole-cell recordings showed that small-diameter Vglut3lineage DRG neurons fire menthol-evoked action potentials and exhibited robust, transient receptor potential melastatin 8 (TRPM8)-dependent discharges at room temperature. This heightened excitability was confirmed by current-clamp and action potential phase-plot analyses, which showed menthol-sensitive Vglut3lineage neurons to have more depolarized membrane potentials, lower firing thresholds, and higher evoked firing frequencies compared with menthol-insensitive Vglut3lineage neurons. A biophysical analysis revealed voltage-gated sodium channel (NaV) currents in menthol-sensitive Vglut3lineage neurons were resistant to entry into slow inactivation compared with menthol-insensitive neurons. Multiplex in situ hybridization showed similar distributions of tetrodotoxin (TTX)-sensitive NaV transcripts between TRPM8-positive and -negative Vglut3lineage neurons; however, NaV1.8 transcripts, which encode TTX-resistant channels, were more prevalent in TRPM8-negative neurons. Conversely, pharmacological analyses identified distinct functional contributions of NaV subunits, with NaV1.1 driving firing in menthol-sensitive neurons, whereas other small-diameter Vglut3lineage neurons rely primarily on TTX-resistant NaV channels. Additionally, when NaV1.1 channels were blocked, the remaining NaV current readily entered into slow inactivation in menthol-sensitive Vglut3lineage neurons. Thus, these data demonstrate that TTX-sensitive NaVs drive action potential firing in menthol-sensitive sensory neurons and contribute to their heightened excitability.SIGNIFICANCE STATEMENT Somatosensory neurons encode various sensory modalities including thermoreception, mechanoreception, nociception, and itch. This report identifies a previously unknown requirement for tetrodotoxin-sensitive sodium channels in action potential firing in a discrete subpopulation of small-diameter sensory neurons that are activated by the cooling agent menthol. Together, our results provide a mechanistic understanding of factors that control intrinsic excitability in functionally distinct subsets of peripheral neurons. Furthermore, as menthol has been used for centuries as an analgesic and anti-pruritic, these findings support the viability of NaV1.1 as a therapeutic target for sensory disorders.
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Is Optogenetic Activation of Vglut1-Positive Aβ Low-Threshold Mechanoreceptors Sufficient to Induce Tactile Allodynia in Mice after Nerve Injury? J Neurosci 2019; 39:6202-6215. [PMID: 31152125 DOI: 10.1523/jneurosci.2064-18.2019] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 05/08/2019] [Accepted: 05/22/2019] [Indexed: 12/20/2022] Open
Abstract
Mechanical allodynia is a cardinal feature of pathological pain. Recent work has demonstrated the necessity of Aβ-low-threshold mechanoreceptors (Aβ-LTMRs) for mechanical allodynia-like behaviors in mice, but it remains unclear whether these neurons are sufficient to produce pain under pathological conditions. We generated a transgenic mouse in which channelrhodopsin-2 (ChR2) is conditionally expressed in vesicular glutamate transporter 1 (Vglut1) sensory neurons (Vglut1-ChR2), which is a heterogeneous population of large-sized sensory neurons with features consistent with Aβ-LTMRs. In naive male Vglut1-ChR2 mice, transdermal hindpaw photostimulation evoked withdrawal behaviors in an intensity- and frequency-dependent manner, which were abolished by local anesthetic and selective A-fiber blockade. Surprisingly, male Vglut1-ChR2 mice did not show significant differences in light-evoked behaviors or real-time aversion after nerve injury despite marked hypersensitivity to punctate mechanical stimuli. We conclude that optogenetic activation of cutaneous Vglut1-ChR2 neurons alone is not sufficient to produce pain-like behaviors in neuropathic mice.SIGNIFICANCE STATEMENT Mechanical allodynia, in which innocuous touch is perceived as pain, is a common feature of pathological pain. To test the contribution of low-threshold mechanoreceptors (LTMRs) to nerve-injury-induced mechanical allodynia, we generated and characterized a new transgenic mouse (Vglut1-ChR2) to optogenetically activate cutaneous vesicular glutamate transporter 1 (Vglut1)-positive LTMRs. Using this mouse, we found that light-evoked behaviors were unchanged by nerve injury, which suggests that activation of Vglut1-positive LTMRs alone is not sufficient to produce pain. The Vglut1-ChR2 mouse will be broadly useful for the study of touch, pain, and itch.
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23
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da Silva Balin P, Zanatta FC, Jorge BC, Leitão M, Kassuya RM, Cardoso CAL, Kassuya CAL, Arena AC. Toxicological evaluation and anti-inflammatory potential of an ethanolic extract from Bromelia balansae (Bromeliaceae) fruit. JOURNAL OF ETHNOPHARMACOLOGY 2018; 222:79-86. [PMID: 29729384 DOI: 10.1016/j.jep.2018.04.049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 04/30/2018] [Accepted: 04/30/2018] [Indexed: 06/08/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Bromelia balansae is a relatively unexplored medicinal species that is used for nutritional purposes and in folk medicine to treat cough or wounds. AIM OF THIS STUDY This study assessed the anti-inflammatory activity of the ethanolic extract obtained from Bromelia balansae fruit (EEBB) as well as the toxicological potential of this extract after single and repeated exposure. MATERIALS AND METHODS Male rats (Wistar) were gavaged with 2000 mg/kg of extract from the fruit of B. balansae for the acute toxicity test and with 25, 100, or 400 mg/kg of EEBB for the subacute toxicity test. The anti-inflammatory effect of EEBB was evaluated in vivo (30, 100, or 300 mg/kg) by carrageenan (Cg) induced-oedema and pleurisy in Swiss mice. RESULTS A single oral dose of EEBB did not result in toxicity, demonstrating that the LD50 of this extract was greater than 2000 mg/kg. In the subacute toxicity test, the tested doses produced no significant changes in the haematological, biochemical or histopathological parameters of treated animals. Similarly, there were no statistically significant differences in the sperm parameters. A dose of 300 mg/kg of EEBB significantly reduced oedema formation, Cg-induced mechanical hypersensitivity and cold sensitivity, as well as leukocyte migration in the pleurisy model. CONCLUSION These results show that EEBB has an anti-inflammatory potential without causing acute or subacute toxicity. These data may contribute to the advancement of biopharmaceutical applications for this species.
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Affiliation(s)
- Paola da Silva Balin
- Department of Morphology, Institute of Biosciences of Botucatu, UNESP - Univ. Estadual Paulista, Botucatu, São Paulo State, Brazil.
| | - Flavia Carina Zanatta
- Department of Morphology, Institute of Biosciences of Botucatu, UNESP - Univ. Estadual Paulista, Botucatu, São Paulo State, Brazil.
| | - Bárbara Campos Jorge
- Department of Morphology, Institute of Biosciences of Botucatu, UNESP - Univ. Estadual Paulista, Botucatu, São Paulo State, Brazil.
| | - Maicon Leitão
- School of Health Sciences, Federal University of Grande Dourados, Dourados, Mato Grosso do Sul State, Brazil.
| | - Roberto Mikio Kassuya
- School of Health Sciences, Federal University of Grande Dourados, Dourados, Mato Grosso do Sul State, Brazil.
| | - Claudia Andrea Lima Cardoso
- Center for Natural Resource Studies, Mato Grosso do Sul State University (UEMS), Dourados, Mato Grosso do Sul State, Brazil.
| | | | - Arielle Cristina Arena
- Department of Morphology, Institute of Biosciences of Botucatu, UNESP - Univ. Estadual Paulista, Botucatu, São Paulo State, Brazil.
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24
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Xie YF, Wang J, Bonin RP. Optogenetic exploration and modulation of pain processing. Exp Neurol 2018; 306:117-121. [PMID: 29729250 DOI: 10.1016/j.expneurol.2018.05.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/21/2018] [Accepted: 05/01/2018] [Indexed: 12/26/2022]
Abstract
Intractable pain is the single most common cause of disability, affecting more than 20% of the population world-wide. There is accordingly a global effort to decipher how changes in nociceptive processing in the peripheral and central nervous systems contribute to the onset and maintenance of chronic pain. The past several years have brought rapid progress in the adaptation of optogenetic approaches to study and manipulate the activity of sensory afferents and spinal cord neurons in freely behaving animals, and to investigate cortical processing and modulation of pain responses. This review discusses methodological advances that underlie this recent progress, and discusses practical considerations for the optogenetic modulation of nociceptive sensory processing.
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Affiliation(s)
- Yu-Feng Xie
- Leslie Dan Faculty of Pharmacy, University of Toronto, Canada.
| | - Jing Wang
- The Department of Osteoporosis, the People's Hospital of Baoan District, Shenzhen, Guangdong Province, China
| | - Robert P Bonin
- Leslie Dan Faculty of Pharmacy, University of Toronto, Canada.
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Balázsfi D, Fodor A, Török B, Ferenczi S, Kovács KJ, Haller J, Zelena D. Enhanced innate fear and altered stress axis regulation in VGluT3 knockout mice. Stress 2018; 21:151-161. [PMID: 29310485 DOI: 10.1080/10253890.2017.1423053] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Glutamatergic neurons, characterized by vesicular glutamate transporters (VGluT1-3) provide the main excitation in the brain. Their disturbances have been linked to various brain disorders, which could be also modeled by the contextual fear test in rodents. We aimed to characterize the participation of VGluT3 in the development of contextual fear through its contribution to hypothalamic-pituitary-adrenocortical axis (HPA) regulation using knockout (KO) mice. Contextual fear conditioning was induced by foot shock and mice were examined 1 and 7 d later in the same environment comparing wild type with KO. Foot shock increased the immobility time without context specificity. Additionally, foot shock reduced open arm time in the elevated plus maze (EPM) test, and distance traveled in the open field (OF) test, representing the generalization of fear. Moreover, KO mice spent more time with freezing during the contextual fear test, less time in the open arm of the EPM, and traveled a smaller distance in the OF, with less entries into the central area. However, there was no foot shock and genotype interaction suggesting that VGluT3 does not influence the fear conditioning, rather determines anxiety-like characteristic of the mice. The resting hypothalamic CRH mRNA was higher in KO mice with reduced stressor-induced corticosterone elevations. Immunohistochemistry revealed the presence of VGluT3 positive fibers in the paraventricular nucleus of hypothalamus, but not on the hypophysis. As a summary, we confirmed the involvement of VGluT3 in innate fear, but not in the development of fear memory and generalization, with a significant contribution to HPA alterations. Highlights VGluT3 KO mice show innate fear without significant influence on fear memory and generalization. A putative background is the higher resting CRH mRNA level in their PVN and reduced stress-reactivity.
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Affiliation(s)
- Diána Balázsfi
- a Hungarian Academy of Sciences , Institute of Experimental Medicine , Budapest , Hungary
- b János Szentágothai School of Neurosciences , Semmelweis University , Budapest , Hungary
| | - Anna Fodor
- a Hungarian Academy of Sciences , Institute of Experimental Medicine , Budapest , Hungary
- b János Szentágothai School of Neurosciences , Semmelweis University , Budapest , Hungary
| | - Bibiána Török
- a Hungarian Academy of Sciences , Institute of Experimental Medicine , Budapest , Hungary
- b János Szentágothai School of Neurosciences , Semmelweis University , Budapest , Hungary
| | - Szilamér Ferenczi
- a Hungarian Academy of Sciences , Institute of Experimental Medicine , Budapest , Hungary
| | - Krisztina J Kovács
- a Hungarian Academy of Sciences , Institute of Experimental Medicine , Budapest , Hungary
| | - József Haller
- a Hungarian Academy of Sciences , Institute of Experimental Medicine , Budapest , Hungary
| | - Dóra Zelena
- a Hungarian Academy of Sciences , Institute of Experimental Medicine , Budapest , Hungary
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Optogenetic Activation of Non-Nociceptive Aβ Fibers Induces Neuropathic Pain-Like Sensory and Emotional Behaviors after Nerve Injury in Rats. eNeuro 2018; 5:eN-NWR-0450-17. [PMID: 29468190 PMCID: PMC5819669 DOI: 10.1523/eneuro.0450-17.2018] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 01/25/2018] [Indexed: 01/16/2023] Open
Abstract
Neuropathic pain is caused by peripheral nerve injury (PNI). One hallmark symptom is allodynia (pain caused by normally innocuous stimuli), but its mechanistic underpinning remains elusive. Notably, whether selective stimulation of non-nociceptive primary afferent Aβ fibers indeed evokes neuropathic pain-like sensory and emotional behaviors after PNI is unknown, because of the lack of tools to manipulate Aβ fiber function in awake, freely moving animals. In this study, we used a transgenic rat line that enables stimulation of non-nociceptive Aβ fibers by a light-activated channel (channelrhodopsin-2; ChR2). We found that illuminating light to the plantar skin of these rats with PNI elicited pain-like withdrawal behaviors that were resistant to morphine. Light illumination to the skin of PNI rats increased the number of spinal dorsal horn (SDH) Lamina I neurons positive to activity markers (c-Fos and phosphorylated extracellular signal-regulated protein kinase; pERK). Whole-cell recording revealed that optogenetic Aβ fiber stimulation after PNI caused excitation of Lamina I neurons, which were normally silent by this stimulation. Moreover, illuminating the hindpaw of PNI rats resulted in activation of central amygdaloid neurons and produced an aversion to illumination. Thus, these findings provide the first evidence that optogenetic activation of primary afferent Aβ fibers in PNI rats produces excitation of Lamina I neurons and neuropathic pain-like behaviors that were resistant to morphine treatment. This approach may provide a new path for investigating circuits and behaviors of Aβ fiber-mediated neuropathic allodynia with sensory and emotional aspects after PNI and for discovering novel drugs to treat neuropathic pain.
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Abstract
The sensation of pain plays a vital protecting role, alerting organisms about potentially damaging stimuli. Tissue injury is detected by nerve endings of specialized peripheral sensory neurons called nociceptors that are equipped with different ion channels activated by thermal, mechanic, and chemical stimuli. Several transient receptor potential channels have been identified as molecular transducers of thermal stimuli in pain-sensing neurons. Skin injury or inflammation leads to increased sensitivity to thermal and mechanic stimuli, clinically defined as allodynia or hyperalgesia. This hypersensitivity is also characteristic of systemic inflammatory disorders and neuropathic pain conditions. Mechanisms of thermal hyperalgesia include peripheral sensitization of nociceptor afferents and maladaptive changes in pain-encoding neurons within the central nervous system. An important aspect of pain management involves attempts to minimize the development of nociceptor hypersensitivity. However, knowledge about the cellular and molecular mechanisms causing thermal hyperalgesia and allodynia in human subjects is still limited, and such knowledge would be an essential step for the development of more effective therapies.
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Affiliation(s)
- Félix Viana
- Alicante Institute of Neurosciences, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, San Juan de Alicante, Spain.
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Gutruf P, Rogers JA. Implantable, wireless device platforms for neuroscience research. Curr Opin Neurobiol 2017; 50:42-49. [PMID: 29289027 DOI: 10.1016/j.conb.2017.12.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/13/2017] [Accepted: 12/12/2017] [Indexed: 01/19/2023]
Abstract
Recently developed classes of ultraminiaturized wireless devices provide powerful capabilities in neuroscience research, as implantable light sources for simulation/inhibition via optogenetics, as integrated microfluidic systems for programmed pharmacological delivery and as multimodal sensors for physiological measurements. These platforms leverage basic advances in biocompatible materials, semiconductor device designs and systems engineering concepts to afford modes of operation that are qualitatively distinct from those of conventional approaches that tether animals to external hardware by means of optical fibers, electrical cables and/or fluidic tubing. Neuroscience studies that exploit the unique features of these technologies enable insights into neural function through targeted stimulation, inhibition and recording, with spatially and genetically precise manipulation of neural circuit activity. Experimental possibilities include studies in naturalistic, three dimensional environments, investigations of pair-wise or group related social interactions and many other scenarios of interest that cannot be addressed using traditional hardware.
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Affiliation(s)
- Philipp Gutruf
- Departments of Materials Science and Engineering, Biomedical Engineering, Chemistry, Neurological Surgery, Mechanical Engineering, Electrical Engineering and Computer Science, Simpson Querrey Institute & Feinberg Medical School, 2145 Sheridan Road, Evanston, IL 60208, United States
| | - John A Rogers
- Departments of Materials Science and Engineering, Biomedical Engineering, Chemistry, Neurological Surgery, Mechanical Engineering, Electrical Engineering and Computer Science, Simpson Querrey Institute & Feinberg Medical School, 2145 Sheridan Road, Evanston, IL 60208, United States.
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Ren L, Chang MJ, Zhang Z, Dhaka A, Guo Z, Cao YQ. Quantitative Analysis of Mouse Dural Afferent Neurons Expressing TRPM8, VGLUT3, and NF200. Headache 2017; 58:88-101. [PMID: 28925503 DOI: 10.1111/head.13188] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2017] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To quantify the abundance of dural afferent neurons expressing transient receptor potential channel melastatin 8 (TRPM8), vesicular glutamate transporter 3 (VGLUT3), and neurofilament 200 (NF200) in adult mice. BACKGROUND With the increasing use of mice as a model system to study headache mechanisms, it is important to understand the composition of dural afferent neurons in mice. In a previous study, we have measured the abundance of mouse dural afferent neurons that express neuropeptide calcitonin gene-related peptide as well as two TRP channels TRPV1 and TRPA1, respectively. Here, we conducted quantitative analysis of three other dural afferent subpopulations in adult mice. METHODS We used the fluorescent tracer Fluoro-Gold to retrogradely label dural afferent neurons in adult mice expressing enhanced green fluorescent protein in discrete subpopulations of trigeminal ganglion (TG) neurons. Mechanoreceptors with myelinated fibers were identified by NF200 immunoreactivity. We also conducted Ca2+ -imaging experiments to test the overlap between TRPM8 and VGLUT3 expression in mouse primary afferent neurons (PANs). RESULTS The abundance of TRPM8-expressing neurons in dural afferent neurons was significantly lower than that in total TG neurons. The percentages of dural afferent neurons expressing VGLUT3 and NF200 were comparable to those of total TG neurons, respectively. TRPM8 agonist menthol evoked Ca2+ influx in less than 7% VGLUT3-expressing PANs in adult mice. CONCLUSIONS TG neurons expressing TRPM8, VGLUT3, and NF200 all innervate adult mouse dura. TRPM8 and VGLUT3 are expressed in distinct subpopulations of PANs in adult mice. These results provide an anatomical basis to investigate headache mechanisms in mouse models.
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Affiliation(s)
- Lynn Ren
- Washington University Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Michelle Jaehee Chang
- Washington University Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Zhiyu Zhang
- Washington University Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Ajay Dhaka
- Department of Biological Structure, Neurobiology and Behavior Graduate Program, University of Washington, Seattle, WA, USA
| | - Zhaohua Guo
- Washington University Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Yu-Qing Cao
- Washington University Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
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Beaudry H, Daou I, Ribeiro-da-Silva A, Séguéla P. Will optogenetics be used to treat chronic pain patients? Pain Manag 2017; 7:269-278. [PMID: 28726577 DOI: 10.2217/pmt-2016-0055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Chronic pain affects a third of the population and current treatments produce limited relief and severe side effects. An alternative strategy to decrease pain would be to directly modulate somatosensory pathways using optogenetics. Optogenetics involves the use of genetically encoded and optically active proteins, namely opsins, to control neuronal circuits. In preclinical animal models, optical silencing of peripheral nociceptors has been shown to alleviate both inflammatory and neuropathic pain. An opsin-based gene therapy to treat chronic pain patients is not ready yet, but encouraging advances have been made in optical and viral technology. In view of the increasing burden of chronic pain in our aging society, innovative analgesic approaches based on optogenetics are definitely worth exploring.
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Affiliation(s)
- Hélène Beaudry
- Department of Neurology & Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada.,The Alan Edwards Centre for Research on Pain, McGill University, Montreal, Canada.,Department of Pharmacology & Therapeutics, McGill University, Montreal, Canada
| | - Ihab Daou
- Department of Neurology & Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada.,The Alan Edwards Centre for Research on Pain, McGill University, Montreal, Canada
| | - Alfredo Ribeiro-da-Silva
- The Alan Edwards Centre for Research on Pain, McGill University, Montreal, Canada.,Department of Pharmacology & Therapeutics, McGill University, Montreal, Canada
| | - Philippe Séguéla
- Department of Neurology & Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada.,The Alan Edwards Centre for Research on Pain, McGill University, Montreal, Canada
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Copits BA, Pullen MY, Gereau RW. Spotlight on pain: optogenetic approaches for interrogating somatosensory circuits. Pain 2016; 157:2424-2433. [PMID: 27340912 PMCID: PMC5069102 DOI: 10.1097/j.pain.0000000000000620] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Bryan A Copits
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
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Cold sensitivity of TRPA1 is unveiled by the prolyl hydroxylation blockade-induced sensitization to ROS. Nat Commun 2016; 7:12840. [PMID: 27628562 PMCID: PMC5027619 DOI: 10.1038/ncomms12840] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 08/05/2016] [Indexed: 11/08/2022] Open
Abstract
Mammalian transient receptor potential ankyrin 1 (TRPA1) is a polymodal nociceptor that plays an important role in pain generation, but its role as a cold nociceptor is still controversial. Here, we propose that TRPA1 can sense noxious cold via transduction of reactive oxygen species (ROS) signalling. We show that inhibiting hydroxylation of a proline residue within the N-terminal ankyrin repeat of human TRPA1 by mutation or using a prolyl hydroxylase (PHD) inhibitor potentiates the cold sensitivity of TRPA1 in the presence of hydrogen peroxide. Inhibiting PHD in mice triggers mouse TRPA1 sensitization sufficiently to sense cold-evoked ROS, which causes cold hypersensitivity. Furthermore, this phenomenon underlies the acute cold hypersensitivity induced by the chemotherapeutic agent oxaliplatin or its metabolite oxalate. Thus, our findings provide evidence that blocking prolyl hydroxylation reveals TRPA1 sensitization to ROS, which enables TRPA1 to convert ROS signalling into cold sensitivity. The transient receptor potential ankyrin 1 (TRPA1) is a cation channel that is involved in nociceptive pain sensing. Here, the authors show that hydroxylation of a proline in the N terminus of TRPA1 renders it sensitive to reactive oxygen species resulting from noxious cold.
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33
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Seal RP. Do the distinct synaptic properties of VGLUTs shape pain? Neurochem Int 2016; 98:82-8. [PMID: 27180049 DOI: 10.1016/j.neuint.2016.04.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 04/26/2016] [Accepted: 04/28/2016] [Indexed: 11/25/2022]
Abstract
The somatosensory system transmits touch, temperature, itch and pain. Three vesicular glutamate transporter isoforms mediate the release of glutamate throughout the mammalian nervous system with largely non-overlapping distributions and unique roles at the synapse. This review discusses the contribution of each of these essential transporters to circuits underlying pain and other somatosensory behaviors throughout postnatal development and in the adult. A better understanding of the individual contributions of the VGLUT isoforms could provide new avenues for therapeutic intervention.
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Affiliation(s)
- Rebecca P Seal
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; Department of Otolaryngology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; Pittsburgh Center for Pain Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA.
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Montgomery KL, Iyer SM, Christensen AJ, Deisseroth K, Delp SL. Beyond the brain: Optogenetic control in the spinal cord and peripheral nervous system. Sci Transl Med 2016; 8:337rv5. [DOI: 10.1126/scitranslmed.aad7577] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 04/18/2016] [Indexed: 12/12/2022]
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35
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Liu D, Liu Z, Liu H, Li H, Pan X, Li Z. Brain-derived neurotrophic factor promotes vesicular glutamate transporter 3 expression and neurite outgrowth of dorsal root ganglion neurons through the activation of the transcription factors Etv4 and Etv5. Brain Res Bull 2016; 121:215-26. [PMID: 26876757 DOI: 10.1016/j.brainresbull.2016.02.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 01/19/2016] [Accepted: 02/09/2016] [Indexed: 11/29/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is critical for sensory neuron survival and is necessary for vesicular glutamate transporter 3 (VGLUT3) expression. Whether the transcription factors Etv4 and Etv5 are involved in these BDNF-induced effects remains unclear. In the present study, primary cultured dorsal root ganglion (DRG) neurons were used to test the link between BDNF and transcription factors Etv4 and Etv5 on VGLUT3 expression and neurite outgrowth. BDNF promoted the mRNA and protein expression of Etv4 and Etv5 in DRG neurons. These effects were blocked by extracellular signal-regulated protein kinase 1/2 (ERK1/2) inhibitor PD98059 but not phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 or phospholipase C-γ (PLC-γ) inhibitor U73122. Etv4 siRNA and Etv5 siRNA effectively blocked the VGLUT3 expression and neurite elongation induced by BNDF. The overexpression of Etv4 or Etv5 potentiated the effects of BNDF-induced neurite elongation and growth-associated protein 43 (GAP-43), medium neurofilament (NF-M), and light neurofilament (NF-L) expression while these effects could be inhibited by Etv4 and Etv5 siRNA. These data imply that Etv4 and Etv5 are essential transcription factors in modulating BDNF/TrkB signaling-mediated VGLUT3 expression and neurite outgrowth. BDNF, through the ERK1/2 signaling pathway, activates Etv4 and Etv5 to initiate GAP-43 expression, promote neurofilament (NF) protein expression, induce neurite outgrowth, and mediate VGLUT3 expression for neuronal function improvement. The biological effects initiated by BDNF/TrkB signaling linked to E26 transformation-specific (ETS) transcription factors are important to elucidate neuronal differentiation, axonal regeneration, and repair in various pathological states.
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Affiliation(s)
- Dong Liu
- Department of Anatomy, Shandong University School of Medicine, Jinan 250012, China.
| | - Zhen Liu
- Department of Anatomy, Shandong University School of Medicine, Jinan 250012, China.
| | - Huaxiang Liu
- Department of Rheumatology, Shandong University Qilu Hospital, Jinan 250012, China.
| | - Hao Li
- Department of Orthopaedics, Shandong University Qilu Hospital, Jinan 250012, China.
| | - Xinliang Pan
- Department of Otolaryngology, Shandong University Qilu Hospital, Jinan 250012, China.
| | - Zhenzhong Li
- Department of Anatomy, Shandong University School of Medicine, Jinan 250012, China.
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Malet M, Brumovsky PR. VGLUTs and Glutamate Synthesis-Focus on DRG Neurons and Pain. Biomolecules 2015; 5:3416-37. [PMID: 26633536 PMCID: PMC4693284 DOI: 10.3390/biom5043416] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Revised: 11/13/2015] [Accepted: 11/17/2015] [Indexed: 12/14/2022] Open
Abstract
The amino acid glutamate is the principal excitatory transmitter in the nervous system, including in sensory neurons that convey pain sensation from the periphery to the brain. It is now well established that a family of membrane proteins, termed vesicular glutamate transporters (VGLUTs), serve a critical function in these neurons: they incorporate glutamate into synaptic vesicles. VGLUTs have a central role both under normal neurotransmission and pathological conditions, such as neuropathic or inflammatory pain. In the present short review, we will address VGLUTs in the context of primary afferent neurons. We will focus on the role of VGLUTs in pain triggered by noxious stimuli, peripheral nerve injury, and tissue inflammation, as mostly explored in transgenic mice. The possible interplay between glutamate biosynthesis and VGLUT-dependent packaging in synaptic vesicles, and its potential impact in various pain states will be presented.
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Affiliation(s)
- Mariana Malet
- Institute of Research on Translational Medicine, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Austral University, Avenida Juan D. Perón 1500, Pilar, Buenos Aires 1629AHJ, Argentina.
| | - Pablo R Brumovsky
- Institute of Research on Translational Medicine, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Austral University, Avenida Juan D. Perón 1500, Pilar, Buenos Aires 1629AHJ, Argentina.
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Abstract
Distinct subsets of sensory nerve fibres are involved in mediating mechanical and thermal pain hypersensitivity. They may also differentially respond to analgesics. Heat-sensitive C-fibres, for example, are thought to respond to μ-opioid receptor (MOR) activation while mechanoreceptive fibres are supposedly sensitive to δ-opioid receptor (DOR) or GABAB receptor (GABABR) activation. The suggested differential distribution of inhibitory neurotransmitter receptors on different subsets of sensory fibres is, however, heavily debated. In this study, we quantitatively compared the degree of presynaptic inhibition exerted by opioids and the GABABR agonist baclofen on (1) vesicular glutamate transporter subtype 3-positive (VGluT3) non-nociceptive primary afferent fibres and (2) putative nociceptive C-fibres. To investigate VGluT3 sensory fibres, we evoked excitatory postsynaptic currents with blue light at the level of the dorsal root ganglion (DRG) in spinal cord slices of mice, expressing channelrhodopsin-2. Putative nociceptive C-fibres were explored in VGluT3-knockout mice through electrical stimulation. The MOR agonist DAMGO strongly inhibited both VGluT3 and VGluT3 C-fibres innervating lamina I neurons but generally had less influence on fibres innervating lamina II neurons. The DOR agonist SNC80 did not have any pronounced effect on synaptic transmission in any fibre type tested. Baclofen, in striking contrast, powerfully inhibited all fibre populations investigated. In summary, we report optogenetic stimulation of DRG neurons in spinal slices as a capable approach for the subtype-selective investigation of primary afferent nerve fibres. Overall, pharmacological accessibility of different subtypes of sensory fibres considerably overlaps, indicating that MOR, DOR, and GABABR expressions are not substantially segregated between heat and mechanosensitive fibres.
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Abstract
Both clinical and animal studies suggest that exercise may be an effective way to manage inflammatory and neuropathic pain conditions. However, existing animal studies commonly use forced exercise paradigms that incorporate varying degrees of stress, which itself can elicit analgesia, and thus may complicate the interpretation of the effects of exercise on pain. We investigated the analgesic potential of voluntary wheel running in the formalin model of acute inflammatory pain and the spared nerve injury model of neuropathic pain in mice. In uninjured, adult C57BL/6J mice, 1 to 4 weeks of exercise training did not alter nociceptive thresholds, lumbar dorsal root ganglia neuronal excitability, or hindpaw intraepidermal innervation. Further, exercise training failed to attenuate formalin-induced spontaneous pain. Lastly, 2 weeks of exercise training was ineffective in reversing spared nerve injury-induced mechanical hypersensitivity or in improving muscle wasting or hindpaw denervation. These findings indicate that in contrast to rodent forced exercise paradigms, short durations of voluntary wheel running do not improve pain-like symptoms in mouse models of acute inflammation and peripheral nerve injury.
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Incoherent feed-forward regulatory loops control segregation of C-mechanoreceptors, nociceptors, and pruriceptors. J Neurosci 2015; 35:5317-29. [PMID: 25834056 DOI: 10.1523/jneurosci.0122-15.2015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mammalian skin is innervated by diverse, unmyelinated C fibers that are associated with senses of pain, itch, temperature, or touch. A key developmental question is how this neuronal cell diversity is generated during development. We reported previously that the runt domain transcription factor Runx1 is required to coordinate the development of these unmyelinated cutaneous sensory neurons, including VGLUT3(+) low-threshold c-mechanoreceptors (CLTMs), MrgprD(+) polymodal nociceptors, MrgprA3(+) pruriceptors, MrgprB4(+) c-mechanoreceptors, and others. However, how these Runx1-dependent cutaneous sensory neurons are further segregated is poorly illustrated. Here, we find that the Runx1-dependent transcription factor gene Zfp521 is expressed in, and required for establishing molecular features that define, VGLUT3(+) CLTMs. Furthermore, Runx1 and Zfp521 form a classic incoherent feedforward loop (I-FFL) in controlling molecular identities that normally belong to MrgprD(+) neurons, with Runx1 and Zfp51 playing activator and repressor roles, respectively (in genetic terms). A knock-out of Zfp521 allows prospective VGLUT3 lineage neurons to acquire MrgprD(+) neuron identities. Furthermore, Runx1 might form other I-FFLs to regulate the expression of MrgprA3 and MrgprB4, a mechanism preventing these genes from being expressed in Runx1-persistent VGLUT3(+) and MrgprD(+) neurons. The evolvement of these I-FFLs provides an explanation for how modality-selective sensory subtypes are formed during development and may also have intriguing implications for sensory neuron evolution and sensory coding.
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Aberrant synaptic integration in adult lamina I projection neurons following neonatal tissue damage. J Neurosci 2015; 35:2438-51. [PMID: 25673839 DOI: 10.1523/jneurosci.3585-14.2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mounting evidence suggests that neonatal tissue damage evokes alterations in spinal pain reflexes which persist into adulthood. However, less is known about potential concomitant effects on the transmission of nociceptive information to the brain, as the degree to which early injury modulates synaptic integration and membrane excitability in mature spinal projection neurons remains unclear. Here we demonstrate that neonatal surgical injury leads to a significant shift in the balance between synaptic excitation and inhibition onto identified lamina I projection neurons of the adult mouse spinal cord. The strength of direct primary afferent input to mature spino-parabrachial neurons was enhanced following neonatal tissue damage, whereas the efficacy of both GABAergic and glycinergic inhibition onto the same population was compromised. This was accompanied by reorganization in the pattern of sensory input to adult projection neurons, which included a greater prevalence of monosynaptic input from low-threshold A-fibers when preceded by early tissue damage. In addition, neonatal incision resulted in greater primary afferent-evoked action potential discharge in mature projection neurons. Overall, these results demonstrate that tissue damage during early life causes a long-term increase in the gain of spinal nociceptive circuits, and suggest that the prolonged consequences of neonatal trauma may not be restricted to the spinal cord but rather include excessive ascending signaling to supraspinal pain centers.
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Zhu Y, Feng B, Schwartz ES, Gebhart GF, Prescott SA. Novel method to assess axonal excitability using channelrhodopsin-based photoactivation. J Neurophysiol 2015; 113:2242-9. [PMID: 25609112 DOI: 10.1152/jn.00982.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 01/14/2015] [Indexed: 01/30/2023] Open
Abstract
Measuring the excitability of individual axons is complicated by the prohibitive difficulty in obtaining intracellular recordings. Here, we present an innovative methodology that enables local excitability to be measured anywhere in a channelrhodopsin (ChR2)-expressing neuron. The approach hinges on activating ChR2 in a spatially and temporally precise manner while recording the resulting spike train from a remote site. We validated this approach in primary afferent neurons (PANs). Initial encoding of somatosensory stimuli relies on transduction of the physical stimulus into a receptor potential and transformation of the receptor potential into a spike train; the transformation process depends on the excitability of the most distal PAN endings but, as explained above, is extraordinarily difficult to study in situ using traditional methods. Using ChR2-based photoactivation, we show 1) that excitability differs between the distal endings and more proximal portions of PAN axons, 2) that the transformation process differs between PANs, and 3) that the transformation process is directly affected by inflammation. Beyond presenting an innovative method by which to study axonal excitability, this study has validated its utility in helping to decipher the earliest stages of somatosensory encoding.
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Affiliation(s)
- Yi Zhu
- Center for Pain Research, Department of Anesthesiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Bin Feng
- Center for Pain Research, Department of Anesthesiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Erica S Schwartz
- Center for Pain Research, Department of Anesthesiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - G F Gebhart
- Center for Pain Research, Department of Anesthesiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Steven A Prescott
- Center for Pain Research, Department of Anesthesiology, University of Pittsburgh, Pittsburgh, Pennsylvania; Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Physiology and the Institute for Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
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