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Mulpuri Y, Yamamoto T, Nishimura I, Spigelman I. Role of voltage-gated sodium channels in axonal signal propagation of trigeminal ganglion neurons after infraorbital nerve entrapment. NEUROBIOLOGY OF PAIN 2022; 11:100084. [PMID: 35128176 PMCID: PMC8803652 DOI: 10.1016/j.ynpai.2022.100084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 01/17/2022] [Accepted: 01/17/2022] [Indexed: 11/25/2022]
Abstract
Infraorbital nerve entrapment (IoNE) induces mechanical allodynia and enhances signal propagation in primary afferent A- and C-fibers. IoNE increases sensitivity of A- and C-fibers to conduction block by tetrodotoxin (TTX) and selective voltage-gated sodium channel 1.8 (NaV1.8) inhibitor, A-803467. IoNE increases signal propagation in vibrissal pad Ad -, but not Aβ-fibers, and their sensitivity to conduction block by the selective NaV1.8 inhibitor. IoNE increases membrane excitability of dissociated small and medium sized trigeminal neurons. IoNE increases nerve, but not ganglion, levels of NaV1.3, NaV1.7, and NaV1.8 mRNAs, and NaV1.8 protein.
Chronic pain arising from peripheral nerve injuries represents a significant clinical challenge because even the most efficacious anticonvulsant drug treatments are limited by their side effects profile. We investigated pain behavior, changes in axonal signal conduction and excitability of trigeminal neurons, and expression of voltage-gated sodium channels (NaVs) in the infraorbital nerve and trigeminal ganglion (TG) after infraorbital nerve entrapment (IoNE). Compared to Sham, IoNE rats had increased A- and C-fiber compound action potentials (CAPs) and Aδ component of A-CAP area from fibers innervating the vibrissal pad. After IoNE, A- and C-fiber CAPs were more sensitive to blockade by tetrodotoxin (TTX), and those fibers that were TTX-resistant were more sensitive to blockade by the NaV1.8 selective blocker, A-803467. Although NaV1.7 blocker, ICA-121431 alone, did not affect Aδ-fiber signal propagation, cumulative application with A-803467 and 4,9-anhydro-TTX significantly reduced the Aδ-fiber CAP in IoNE rats. In patch clamp recordings from small- and medium-sized TG neurons, IoNE resulted in reduced action potential (AP) depolarizing current threshold, hyperpolarized AP voltage threshold, increased AP duration, and a more depolarized membrane potential. While the transcripts of most NaVs were reduced in the ipsilateral TG after IoNE, NaV1.3, NaV1.7, and NaV1.8 mRNAs, and NaV1.8 protein, were significantly increased in the nerve. Altogether, our data suggest that axonal redistribution of NaV1.8, and to a lesser extent NaV1.3, and NaV1.7 contributes to enhanced nociceptive signal propagation in peripheral nerve after IoNE.
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Cai S, Moutal A, Yu J, Chew LA, Isensee J, Chawla R, Gomez K, Luo S, Zhou Y, Chefdeville A, Madura C, Perez-Miller S, Bellampalli SS, Dorame A, Scott DD, François-Moutal L, Shan Z, Woodward T, Gokhale V, Hohmann AG, Vanderah TW, Patek M, Khanna M, Hucho T, Khanna R. Selective targeting of NaV1.7 via inhibition of the CRMP2-Ubc9 interaction reduces pain in rodents. Sci Transl Med 2021; 13:eabh1314. [PMID: 34757807 DOI: 10.1126/scitranslmed.abh1314] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The voltage-gated sodium NaV1.7 channel, critical for sensing pain, has been actively targeted by drug developers; however, there are currently no effective and safe therapies targeting NaV1.7. Here, we tested whether a different approach, indirect NaV1.7 regulation, could have antinociceptive effects in preclinical models. We found that preventing addition of small ubiquitin-like modifier (SUMO) on the NaV1.7-interacting cytosolic collapsin response mediator protein 2 (CRMP2) blocked NaV1.7 functions and had antinociceptive effects in rodents. In silico targeting of the SUMOylation site in CRMP2 (Lys374) identified >200 hits, of which compound 194 exhibited selective in vitro and ex vivo NaV1.7 engagement. Orally administered 194 was not only antinociceptive in preclinical models of acute and chronic pain but also demonstrated synergy alongside other analgesics—without eliciting addiction, rewarding properties, or neurotoxicity. Analgesia conferred by 194 was opioid receptor dependent. Our results demonstrate that 194 is a first-in-class protein-protein inhibitor that capitalizes on CRMP2-NaV1.7 regulation to deliver safe analgesia in rodents.
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Affiliation(s)
- Song Cai
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Aubin Moutal
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Jie Yu
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Lindsey A Chew
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Jörg Isensee
- Department of Anesthesiology and Intensive Care Medicine, Translational Pain Research, University Hospital of Cologne, University Cologne, Joseph-Stelzmann-Str 9, Cologne D-50931, Germany
| | - Reena Chawla
- BIO5 Institute, 1657 East Helen Street, Tucson, AZ 85721, USA
| | - Kimberly Gomez
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Shizhen Luo
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Yuan Zhou
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Aude Chefdeville
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Cynthia Madura
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Samantha Perez-Miller
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
- Center for Innovation in Brain Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - Shreya Sai Bellampalli
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Angie Dorame
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - David D Scott
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Liberty François-Moutal
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Zhiming Shan
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Taylor Woodward
- Department of Psychological and Brain Sciences, Program in Neuroscience and Gill Center for Biomolecular Science, Indiana University, Bloomington, IN 47405-2204, USA
| | - Vijay Gokhale
- BIO5 Institute, 1657 East Helen Street, Tucson, AZ 85721, USA
- College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, AZ 85721, USA
| | - Andrea G Hohmann
- Department of Psychological and Brain Sciences, Program in Neuroscience and Gill Center for Biomolecular Science, Indiana University, Bloomington, IN 47405-2204, USA
| | - Todd W Vanderah
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
- Comprehensive Pain and Addiction Center, The University of Arizona, Tucson, AZ 85724, USA
| | - Marcel Patek
- Regulonix LLC, 1555 E. Entrada Segunda, Tucson, AZ 85718, USA
- Bright Rock Path LLC, Tucson, AZ 85724, USA
| | - May Khanna
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
- BIO5 Institute, 1657 East Helen Street, Tucson, AZ 85721, USA
- Center for Innovation in Brain Sciences, University of Arizona, Tucson, AZ 85721, USA
- Regulonix LLC, 1555 E. Entrada Segunda, Tucson, AZ 85718, USA
| | - Tim Hucho
- Department of Anesthesiology and Intensive Care Medicine, Translational Pain Research, University Hospital of Cologne, University Cologne, Joseph-Stelzmann-Str 9, Cologne D-50931, Germany
| | - Rajesh Khanna
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ 85724, USA
- BIO5 Institute, 1657 East Helen Street, Tucson, AZ 85721, USA
- Center for Innovation in Brain Sciences, University of Arizona, Tucson, AZ 85721, USA
- Comprehensive Pain and Addiction Center, The University of Arizona, Tucson, AZ 85724, USA
- Regulonix LLC, 1555 E. Entrada Segunda, Tucson, AZ 85718, USA
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García G, Noriega-Navarro R, Martínez-Rojas VA, Gutiérrez-Lara EJ, Oviedo N, Murbartián J. Spinal TASK-1 and TASK-3 modulate inflammatory and neuropathic pain. Eur J Pharmacol 2019; 862:172631. [DOI: 10.1016/j.ejphar.2019.172631] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 08/09/2019] [Accepted: 08/27/2019] [Indexed: 12/13/2022]
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Li M, Zhang SJ, Yang L, Fang XL, Hu HF, Zhao MY, Li L, Guo YY, Shao JP. Voltage-gated sodium channel 1.7 expression decreases in dorsal root ganglia in a spinal nerve ligation neuropathic pain model. Kaohsiung J Med Sci 2019; 35:493-500. [PMID: 31087766 DOI: 10.1002/kjm2.12088] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 04/30/2019] [Indexed: 02/06/2023] Open
Abstract
The role of the voltage-gated sodium channel 1.7 (Nav1.7) is unclear in models of neuropathic pain induced by nerve injury. In the present study, we measured expression levels of Nav1.7 in two distinct neuropathic pain models: spinal nerve ligation (SNL) and chronic constriction injury (CCI). In the SNL model, both mRNA and protein levels of Nav1.7 were markedly lower in the L5 dorsal root ganglia (DRG) but were significantly higher in the L4 DRG. Nav1.7 protein levels were notably higher in both L4 and L5 DRGs under CCI conditions. We found that excessive damage of L5 nerves such as SNL reduced expression levels of Nav1.7 in the injured L5 DRG and activated the adjacent uninjured DRG, resulting in Nav1.7 level increases in the adjacent L4 DRG. We confirmed again that Nav1.7 was closely related to neuropathic pain induced by nerve injury. More importantly, our results suggest that tracing the molecular changes exclusively in the L5 DRG in SNL model may not completely explain the pain mechanism; it is necessary to study the adjacent uninjured L4 DRG.
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Affiliation(s)
- Ming Li
- Department of Human Anatomy, School of Basic Medicine, Zhengzhou University, Zhengzhou, China
| | - Shao-Jin Zhang
- School of Basic Medicine, Zhengzhou University, Zhengzhou, China
| | - Lin Yang
- School of Basic Medicine, Zhengzhou University, Zhengzhou, China
| | - Xiao-Lei Fang
- School of Basic Medicine, Zhengzhou University, Zhengzhou, China
| | - Hao-Fan Hu
- School of Basic Medicine, Zhengzhou University, Zhengzhou, China
| | - Ming-Yue Zhao
- School of Basic Medicine, Zhengzhou University, Zhengzhou, China
| | - Lei Li
- Department of Human Anatomy, School of Basic Medicine, Zhengzhou University, Zhengzhou, China
| | - Yan-Yan Guo
- Department of Human Anatomy, School of Basic Medicine, Zhengzhou University, Zhengzhou, China
| | - Jin-Ping Shao
- Department of Human Anatomy, School of Basic Medicine, Zhengzhou University, Zhengzhou, China
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Morgalla MH, de Barros Filho MF, Chander BS, Soekadar SR, Tatagiba M, Lepski G. Neurophysiological Effects of Dorsal Root Ganglion Stimulation (DRGS) in Pain Processing at the Cortical Level. Neuromodulation 2018; 22:36-43. [PMID: 30561852 DOI: 10.1111/ner.12900] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 10/25/2018] [Accepted: 10/25/2018] [Indexed: 12/14/2022]
Abstract
OBJECTIVES Dorsal root ganglion stimulation (DRGS) has been used successfully against localized neuropathic pain. Nevertheless, the effects of DRGS on pain processing, particularly at the cortical level, remain largely unknown. In this study, we investigated whether positive responses to DRGS treatment would alter patients' laser-evoked potentials (LEP). METHODS We prospectively enrolled 12 adult patients with unilateral localized neuropathic pain in the lower limbs or inguinal region and followed them up for six months. LEPs were assessed at baseline, after one month of DRGS, and after six months of DRGS. Clinical assessment included the Numerical Rating Scale (NRS), Brief Pain Inventory (BPI), SF-36, and Beck Depression Inventory (BDI). For each patient, LEP amplitudes and latencies of the N2 and P2 components on the deafferented side were measured and compared to those of the healthy side and correlated with pain intensity, as measured with the NRS. RESULTS At the one- and six-month follow-ups, N2-P2 amplitudes were significantly greater and NRS scores were significantly lower compared with baseline (all p's < 0.01). There was a negative correlation between LEP amplitudes and NRS scores (rs = -0.31, p < 0.10). CONCLUSIONS DRGS is able to restore LEPs to normal values in patients with localized neuropathic pain, and LEP alterations are correlated with clinical response in terms of pain intensity.
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Affiliation(s)
| | - Marcos Fortunato de Barros Filho
- Department of Neurosurgery, University of Tuebingen, Tuebingen, Germany.,Applied Neurotechnology Laboratory, Department of Psychiatry and Psychotherapy, University of Tuebingen, Tuebingen, Germany.,Division of Functional Neurosurgery, School of Medicine, Universidade de São Paulo, São Paulo, Brazil
| | - Bankim Subhash Chander
- Department of Neurosurgery, University of Tuebingen, Tuebingen, Germany.,Applied Neurotechnology Laboratory, Department of Psychiatry and Psychotherapy, University of Tuebingen, Tuebingen, Germany
| | - Surjo Raphael Soekadar
- Applied Neurotechnology Laboratory, Department of Psychiatry and Psychotherapy, University of Tuebingen, Tuebingen, Germany.,Clinical Neurotechnology Laboratory, Neuroscience Research Center (NWFZ) & Department of Psychiatry and Psychotherapy, Charité - University Medicine Berlin, Berlin, Germany
| | - Marcos Tatagiba
- Department of Neurosurgery, University of Tuebingen, Tuebingen, Germany
| | - Guilherme Lepski
- Department of Neurosurgery, University of Tuebingen, Tuebingen, Germany.,Division of Functional Neurosurgery, School of Medicine, Universidade de São Paulo, São Paulo, Brazil
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Guha D, Shamji MF. The Dorsal Root Ganglion in the Pathogenesis of Chronic Neuropathic Pain. Neurosurgery 2018; 63 Suppl 1:118-126. [PMID: 27399376 DOI: 10.1227/neu.0000000000001255] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Affiliation(s)
| | - Mohammed F Shamji
- Department of Surgery and.,Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.,Division of Neurosurgery, Toronto Western Hospital, Toronto, Ontario, Canada
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García G, Martínez-Rojas VA, Oviedo N, Murbartián J. Blockade of anoctamin-1 in injured and uninjured nerves reduces neuropathic pain. Brain Res 2018; 1696:38-48. [DOI: 10.1016/j.brainres.2018.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 04/12/2018] [Accepted: 06/01/2018] [Indexed: 12/28/2022]
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DRG Voltage-Gated Sodium Channel 1.7 Is Upregulated in Paclitaxel-Induced Neuropathy in Rats and in Humans with Neuropathic Pain. J Neurosci 2017; 38:1124-1136. [PMID: 29255002 DOI: 10.1523/jneurosci.0899-17.2017] [Citation(s) in RCA: 154] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 11/10/2017] [Accepted: 12/08/2017] [Indexed: 11/21/2022] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is a common adverse effect experienced by cancer patients receiving treatment with paclitaxel. The voltage-gated sodium channel 1.7 (Nav1.7) plays an important role in multiple preclinical models of neuropathic pain and in inherited human pain phenotypes, and its gene expression is increased in dorsal root ganglia (DRGs) of paclitaxel-treated rats. Hence, the potential of change in the expression and function of Nav1.7 protein in DRGs from male rats with paclitaxel-related CIPN and from male and female humans with cancer-related neuropathic pain was tested here. Double immunofluorescence in CIPN rats showed that Nav1.7 was upregulated in small DRG neuron somata, especially those also expressing calcitonin gene-related peptide (CGRP), and in central processes of these cells in the superficial spinal dorsal horn. Whole-cell patch-clamp recordings in rat DRG neurons revealed that paclitaxel induced an enhancement of ProTx II (a selective Nav1.7 channel blocker)-sensitive sodium currents. Bath-applied ProTx II suppressed spontaneous action potentials in DRG neurons occurring in rats with CIPN, while intrathecal injection of ProTx II significantly attenuated behavioral signs of CIPN. Complementarily, DRG neurons isolated from segments where patients had a history of neuropathic pain also showed electrophysiological and immunofluorescence results indicating an increased expression of Nav1.7 associated with spontaneous activity. Nav1.7 was also colocalized in human cells expressing transient receptor potential vanilloid 1 and CGRP. Furthermore, ProTx II decreased firing frequency in human DRGs with spontaneous action potentials. This study suggests that Nav1.7 may provide a potential new target for the treatment of neuropathic pain, including chemotherapy (paclitaxel)-induced neuropathic pain.SIGNIFICANCE STATEMENT This work demonstrates that the expression and function of the voltage-gated sodium channel Nav1.7 are increased in a preclinical model of chemotherapy-induced peripheral neuropathy (CIPN), the most common treatment-limiting side effect of all the most common anticancer therapies. This is key as gain-of-function mutations in human Nav1.7 recapitulate both the distribution and pain percept as shown by CIPN patients. This work also shows that Nav1.7 is increased in human DRG neurons only in dermatomes where patients are experiencing acquired neuropathic pain symptoms. This work therefore has major translational impact, indicating an important novel therapeutic avenue for neuropathic pain as a class.
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10
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Affiliation(s)
- Peter J Shortland
- School of Science & Health, School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - David A Mahns
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
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11
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Ramachandra R, Elmslie KS. EXPRESS: Voltage-dependent sodium (NaV) channels in group IV sensory afferents. Mol Pain 2016; 12:12/0/1744806916660721. [PMID: 27385723 PMCID: PMC4956173 DOI: 10.1177/1744806916660721] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Patients with intermittent claudication suffer from both muscle pain and an exacerbated exercise pressor reflex. Excitability of the group III and group IV afferent fibers mediating these functions is controlled in part by voltage-dependent sodium (NaV) channels. We previously found tetrodotoxin-resistant NaV1.8 channels to be the primary type in muscle afferent somata. However, action potentials in group III and IV afferent axons are blocked by TTX, supporting a minimal role of NaV1.8 channels. To address these apparent differences in NaV channel expression between axon and soma, we used immunohistochemistry to identify the NaV channels expressed in group IV axons within the gastrocnemius muscle and the dorsal root ganglia sections. Positive labeling by an antibody against the neurofilament protein peripherin was used to identify group IV neurons and axons. We show that >67% of group IV fibers express NaV1.8, NaV1.6, or NaV1.7. Interestingly, expression of NaV1.8 channels in group IV somata was significantly higher than in the fibers, whereas there were no significant differences for either NaV1.6 or NaV1.7. When combined with previous work, our results suggest that NaV1.8 channels are expressed in most group IV axons, but that, under normal conditions, NaV1.6 and/or NaV1.7 play a more important role in action potential generation to signal muscle pain and the exercise pressor reflex.
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Affiliation(s)
- Renuka Ramachandra
- The Baker Laboratory of Pharmacology, Department of Pharmacology, AT Still University of Health Sciences, Kirksville, MO, USA
- Renuka Ramachandra, The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, AT Still University of Health Sciences, Kirksville, MO 63501, USA.
| | - Keith S Elmslie
- The Baker Laboratory of Pharmacology, Department of Pharmacology, AT Still University of Health Sciences, Kirksville, MO, USA
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12
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Selective spider toxins reveal a role for the Nav1.1 channel in mechanical pain. Nature 2016; 534:494-9. [PMID: 27281198 PMCID: PMC4919188 DOI: 10.1038/nature17976] [Citation(s) in RCA: 201] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 04/06/2016] [Indexed: 01/19/2023]
Abstract
Voltage-gated sodium (Nav) channels initiate action potentials in most neurons, including primary afferent nerve fibres of the pain pathway. Local anaesthetics block pain through non-specific actions at all Nav channels, but the discovery of selective modulators would facilitate the analysis of individual subtypes of these channels and their contributions to chemical, mechanical, or thermal pain. Here we identify and characterize spider (Heteroscodra maculata) toxins that selectively activate the Nav1.1 subtype, the role of which in nociception and pain has not been elucidated. We use these probes to show that Nav1.1-expressing fibres are modality-specific nociceptors: their activation elicits robust pain behaviours without neurogenic inflammation and produces profound hypersensitivity to mechanical, but not thermal, stimuli. In the gut, high-threshold mechanosensitive fibres also express Nav1.1 and show enhanced toxin sensitivity in a mouse model of irritable bowel syndrome. Together, these findings establish an unexpected role for Nav1.1 channels in regulating the excitability of sensory nerve fibres that mediate mechanical pain.
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13
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Medici T, Shortland PJ. Effects of peripheral nerve injury on parvalbumin expression in adult rat dorsal root ganglion neurons. BMC Neurosci 2015; 16:93. [PMID: 26674138 PMCID: PMC4681077 DOI: 10.1186/s12868-015-0232-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 12/07/2015] [Indexed: 12/24/2022] Open
Abstract
Background Parvalbumin (PV) is a calcium binding protein that identifies a subpopulation of proprioceptive dorsal root ganglion (DRG) neurons. Calcitonin gene-related peptide (CGRP) is also expressed in a high proportion of muscle afferents but its relationship to PV is unclear. Little is known of the phenotypic responses of muscle afferents to nerve injury. Sciatic nerve axotomy or L5 spinal nerve ligation and section (SNL) lesions were used to explore these issues in adult rats using immunocytochemistry. Results In naive animals, the mean PV expression was 25 % of L4 or L5 dorsal root ganglion (DRG) neurons, and this was unchanged 2 weeks after sciatic nerve axotomy. Colocalization studies with the injury marker activating transcription factor 3 (ATF3) showed that approximately 24 % of PV neurons expressed ATF3 after sciatic nerve axotomy suggesting that PV may show a phenotypic switch from injured to uninjured neurons. This possibility was further assessed using the spinal nerve ligation (SNL) injury model where injured and uninjured neurons are located in different DRGs. Two weeks after L5 SNL there was no change in total PV staining and essentially all L5 PV neurons expressed ATF3. Additionally, there was no increase in PV-ir in the adjacent uninjured L4 DRG cells. Co-labelling of DRG neurons revealed that less than 2 % of PV neurons normally expressed CGRP and no colocalization was seen after injury. Conclusion These experiments clearly show that axotomy does not produce down regulation of PV protein in the DRG. Moreover, this lack of change is not due to a phenotypic switch in PV immunoreactive (ir) neurons, or de novo expression of PV-ir in uninjured neurons after nerve injury. These results further illustrate differences that occur when muscle afferents are injured as compared to cutaneous afferents.
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Affiliation(s)
- Tom Medici
- Centre for Neuroscience and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Newark Street, London, E1 2AT, UK. .,Queens Hospital, Romford, Essex, RM7 0AG, UK.
| | - Peter J Shortland
- School of Science and Health, Western Sydney University, Narellen Road, Campbelltown, NSW, 2560, Australia. .,Centre for Neuroscience and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Newark Street, London, E1 2AT, UK.
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Alvarez P, Levine JD. Antihyperalgesic effect of tetrodotoxin in rat models of persistent muscle pain. Neuroscience 2015; 311:499-507. [PMID: 26548414 DOI: 10.1016/j.neuroscience.2015.10.059] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/26/2015] [Accepted: 10/30/2015] [Indexed: 11/29/2022]
Abstract
Persistent muscle pain is a common and disabling symptom for which available treatments have limited efficacy. Since tetrodotoxin (TTX) displays a marked antinociceptive effect in models of persistent cutaneous pain, we tested its local antinociceptive effect in rat models of muscle pain induced by inflammation, ergonomic injury and chemotherapy-induced neuropathy. While local injection of TTX (0.03-1 μg) into the gastrocnemius muscle did not affect the mechanical nociceptive threshold in naïve rats, exposure to the inflammogen carrageenan produced a marked muscle mechanical hyperalgesia, which was dose-dependently inhibited by TTX. This antihyperalgesic effect was still significant at 24h. TTX also displayed a robust antinociceptive effect on eccentric exercise-induced mechanical hyperalgesia in the gastrocnemius muscle, a model of ergonomic pain. Finally, TTX produced a small but significant inhibition of neuropathic muscle pain induced by systemic administration of the cancer chemotherapeutic agent oxaliplatin. These results indicate that TTX-sensitive sodium currents in nociceptors play a central role in diverse states of skeletal muscle nociceptive sensitization, supporting the suggestion that therapeutic interventions based on TTX may prove useful in the treatment of muscle pain.
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Affiliation(s)
- P Alvarez
- Department of Oral and Maxillofacial Surgery, University of California San Francisco, San Francisco, CA, USA
| | - J D Levine
- Department of Oral and Maxillofacial Surgery, University of California San Francisco, San Francisco, CA, USA; Department of Medicine, University of California San Francisco, San Francisco, CA, USA.
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15
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Bao L. Trafficking regulates the subcellular distribution of voltage-gated sodium channels in primary sensory neurons. Mol Pain 2015; 11:61. [PMID: 26423360 PMCID: PMC4590712 DOI: 10.1186/s12990-015-0065-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 09/23/2015] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (Navs) comprise at least nine pore-forming α subunits. Of these, Nav1.6, Nav1.7, Nav1.8 and Nav1.9 are the most frequently studied in primary sensory neurons located in the dorsal root ganglion and are mainly localized to the cytoplasm. A large pool of intracellular Navs raises the possibility that changes in Nav trafficking could alter channel function. The molecular mediators of Nav trafficking mainly consist of signals within the Navs themselves, interacting proteins and extracellular factors. The surface expression of Navs is achieved by escape from the endoplasmic reticulum and proteasome degradation, forward trafficking and plasma membrane anchoring, and it is also regulated by channel phosphorylation and ubiquitination in primary sensory neurons. Axonal transport and localization of Navs in afferent fibers involves the motor protein KIF5B and scaffold proteins, including contactin and PDZ domain containing 2. Localization of Nav1.6 to the nodes of Ranvier in myelinated fibers of primary sensory neurons requires node formation and the submembrane cytoskeletal protein complex. These findings inform our understanding of the molecular and cellular mechanisms underlying Nav trafficking in primary sensory neurons.
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Affiliation(s)
- Lan Bao
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, 200031, China.
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