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Ghovanloo MR, Effraim PR, Yuan JH, Schulman BR, Jacobs DS, Dib-Hajj SD, Waxman SG. Nav1.7 P610T mutation in two siblings with persistent ocular pain after corneal axon transection: impaired slow inactivation and hyperexcitable trigeminal neurons. J Neurophysiol 2023; 129:609-618. [PMID: 36722722 PMCID: PMC9988530 DOI: 10.1152/jn.00457.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 01/27/2023] [Accepted: 01/28/2023] [Indexed: 02/02/2023] Open
Abstract
Despite extensive study, the mechanisms underlying pain after axonal injury remain incompletely understood. Pain after corneal refractive surgery provides a model, in humans, of the effect of injury to trigeminal afferent nerves. Axons of trigeminal ganglion neurons that innervate the cornea are transected by laser-assisted in situ keratomileusis (LASIK). Although most patients do not experience postoperative pain, a small subgroup develop persistent ocular pain. We previously carried out genomic analysis and determined that some patients with persistent pain after axotomy of corneal axons during refractive surgery carry mutations in genes that encode the electrogenisome of trigeminal ganglion neurons, the ensemble of ion channels and receptors that regulate excitability within these cells, including SCN9A, which encodes sodium channel Nav1.7, a threshold channel abundantly expressed in sensory neurons that has been implicated in a number of pain-related disorders. Here, we describe the biophysical and electrophysiological profiling of the P610T Nav1.7 mutation found in two male siblings with persistent ocular pain after refractive surgery. Our results indicate that this mutation impairs the slow inactivation of Nav1.7. As expected from this proexcitatory change in channel function, we also demonstrate that this mutation produces increased spontaneous activity in trigeminal ganglion neurons. These findings suggest that this gain-of-function mutation in Nav1.7 may contribute to pain after injury to the axons of trigeminal ganglion neurons.NEW & NOTEWORTHY Mechanisms underlying pain after axonal injury remain elusive. A small subgroup of patients experience pain after corneal refractive surgery, providing a human pain model after well-defined injury to axons. Here we analyze a mutation (P610T) in Nav1.7, a threshold sodium channel expressed in nociceptors, found in two siblings with persistent ocular pain after refractive surgery. We show that it impairs channel slow inactivation, thereby triggering inappropriate repetitive activity in trigeminal ganglion axons that signal eye pain.
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Affiliation(s)
- Mohammad-Reza Ghovanloo
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, United States
- Center for Neuroscience and Regeneration Research, Yale University, West Haven, Connecticut, United States
- Neuro-Rehabilitation Research Center, Department of Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut, United States
| | - Philip R Effraim
- Center for Neuroscience and Regeneration Research, Yale University, West Haven, Connecticut, United States
- Neuro-Rehabilitation Research Center, Department of Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut, United States
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States
| | - Jun-Hui Yuan
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, United States
- Center for Neuroscience and Regeneration Research, Yale University, West Haven, Connecticut, United States
- Neuro-Rehabilitation Research Center, Department of Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut, United States
| | - Betsy R Schulman
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, United States
- Center for Neuroscience and Regeneration Research, Yale University, West Haven, Connecticut, United States
- Neuro-Rehabilitation Research Center, Department of Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut, United States
| | - Deborah S Jacobs
- Cornea and Refractive Surgery Service, Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, United States
| | - Sulayman D Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, United States
- Center for Neuroscience and Regeneration Research, Yale University, West Haven, Connecticut, United States
- Neuro-Rehabilitation Research Center, Department of Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut, United States
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, United States
- Center for Neuroscience and Regeneration Research, Yale University, West Haven, Connecticut, United States
- Neuro-Rehabilitation Research Center, Department of Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut, United States
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2
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Bromberg H, Guastella A, Haas M, Akel R, Craig D. Two Patients Experience Same-Day Analgesic Effect of Methadone on Trigeminal Neuralgia Secondary to Malignancy: A Case Report. J Palliat Med 2023. [PMID: 36633599 DOI: 10.1089/jpm.2022.0436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Trigeminal neuralgia (TN) secondary to malignancy leads to significant distress and subsequently impacts a patient's quality of life. Use of methadone as a first-line opioid analgesic in this subset of oncology patients is uncommon and is rarely initiated after traditional first-line therapies have failed. We report two patients with TN secondary to tumor burden who experienced significant analgesia within 24 hours of methadone initiation.
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Affiliation(s)
- Hannah Bromberg
- Department of Supportive Care, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA
| | - Ann Guastella
- Department of Supportive Care, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA
| | - Meghan Haas
- Department of Supportive Care, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA
| | - Reem Akel
- Department of Supportive Care, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA
- Department of Graduate Medical Education, University of South Florida, Tampa, Florida, USA
| | - David Craig
- Department of Supportive Care, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA
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Quinn RK, Drury HR, Cresswell ET, Tadros MA, Nayagam BA, Callister RJ, Brichta AM, Lim R. Expression and Physiology of Voltage-Gated Sodium Channels in Developing Human Inner Ear. Front Neurosci 2021; 15:733291. [PMID: 34759790 PMCID: PMC8575412 DOI: 10.3389/fnins.2021.733291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/29/2021] [Indexed: 11/13/2022] Open
Abstract
Sodium channel expression in inner ear afferents is essential for the transmission of vestibular and auditory information to the central nervous system. During development, however, there is also a transient expression of Na+ channels in vestibular and auditory hair cells. Using qPCR analysis, we describe the expression of four Na+ channel genes, SCN5A (Nav1.5), SCN8A (Nav1.6), SCN9A (Nav1.7), and SCN10A (Nav1.8) in the human fetal cristae ampullares, utricle, and base, middle, and apex of the cochlea. Our data show distinct patterns of Na+ channel gene expression with age and between these inner ear organs. In the utricle, there was a general trend toward fold-change increases in expression of SCN8A, SCN9A, and SCN10A with age, while the crista exhibited fold-change increases in SCN5A and SCN8A and fold-change decreases in SCN9A and SCN10A. Fold-change differences of each gene in the cochlea were more complex and likely related to distinct patterns of expression based on tonotopy. Generally, the relative expression of SCN genes in the cochlea was greater than that in utricle and cristae ampullares. We also recorded Na+ currents from developing human vestibular hair cells aged 10-11 weeks gestation (WG), 12-13 WG, and 14+ WG and found there is a decrease in the number of vestibular hair cells that exhibit Na+ currents with increasing gestational age. Na+ current properties and responses to the application of tetrodotoxin (TTX; 1 μM) in human fetal vestibular hair cells are consistent with those recorded in other species during embryonic and postnatal development. Both TTX-sensitive and TTX-resistant currents are present in human fetal vestibular hair cells. These results provide a timeline of sodium channel gene expression in inner ear neuroepithelium and the physiological characterization of Na+ currents in human fetal vestibular neuroepithelium. Understanding the normal developmental timeline of ion channel gene expression and when cells express functional ion channels is essential information for regenerative technologies.
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Affiliation(s)
- Rikki K Quinn
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Hannah R Drury
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Ethan T Cresswell
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Melissa A Tadros
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Bryony A Nayagam
- Department of Audiology and Speech Pathology, The University of Melbourne, Parkville, VIC, Australia
| | - Robert J Callister
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Alan M Brichta
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Rebecca Lim
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
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Zu M, Guo WW, Cong T, Ji F, Zhang SL, Zhang Y, Song X, Sun W, He DZZ, Shi WG, Yang SM. SCN11A gene deletion causes sensorineural hearing loss by impairing the ribbon synapses and auditory nerves. BMC Neurosci 2021; 22:18. [PMID: 33752606 PMCID: PMC7986359 DOI: 10.1186/s12868-021-00613-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 01/20/2021] [Indexed: 11/10/2022] Open
Abstract
Background The SCN11A gene, encoded Nav1.9 TTX resistant sodium channels, is a main effector in peripheral inflammation related pain in nociceptive neurons. The role of SCN11A gene in the auditory system has not been well characterized. We therefore examined the expression of SCN11A in the murine cochlea, the morphological and physiological features of Nav1.9 knockout (KO) ICR mice. Results Nav1.9 expression was found in the primary afferent endings beneath the inner hair cells (IHCs). The relative quantitative expression of Nav1.9 mRNA in modiolus of wild-type (WT) mice remains unchanged from P0 to P60. The number of presynaptic CtBP2 puncta in Nav1.9 KO mice was significantly lower than WT. In addition, the number of SGNs in Nav1.9 KO mice was also less than WT in the basal turn, but not in the apical and middle turns. There was no lesion in the somas and stereocilia of hair cells in Nav1.9 KO mice. Furthermore, Nav1.9 KO mice showed higher and progressive elevated ABR threshold at 16 kHz, and a significant increase in CAP thresholds. Conclusions These data suggest a role of Nav1.9 in regulating the function of ribbon synapses and the auditory nerves. The impairment induced by Nav1.9 gene deletion mimics the characters of cochlear synaptopathy.
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Affiliation(s)
- Mian Zu
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Wei-Wei Guo
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Tao Cong
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Fei Ji
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Shi-Li Zhang
- Clinical Hearing Center of Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Yue Zhang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Xin Song
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Wei Sun
- Department of Communicative Disorders and Sciences, Center for Hearing and Deafness, The State University of New York at Buffalo, Buffalo, NY, USA
| | - David Z Z He
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, 68178, USA
| | - Wei-Guo Shi
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China.
| | - Shi-Ming Yang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China. .,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China. .,Key Lab of Hearing Science, Ministry of Education, Beijing, China. .,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China.
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5
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Kamata H, Karibe H, Sato I. Comparison of the expression of neurotransmitter and muscular genesis markers in the postnatal male mouse masseter and trigeminal ganglion during development. J Neurosci Res 2017; 96:1043-1055. [PMID: 29265492 DOI: 10.1002/jnr.24211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 11/30/2017] [Accepted: 12/01/2017] [Indexed: 11/09/2022]
Abstract
Calcitonin gene-related peptide (CGRP) is released by motor neurons and affects skeletal muscle fiber and transient receptor potential cation channel subfamily V member 1 (TRPV1), an important marker of pain modulation. However, the expression of CGRP and TRPV1 in the trigeminal ganglion (TG) during changes and in feeding patterns has not been described. We used real-time reverse transcription polymerase chain reaction and in situ hybridization to investigate the mRNA expression levels of CGRP and TRPV1 in the TG. The expression of myosin heavy-chain (MyHC) isoforms was also investigated in the masseter muscle (MM) during the transition from sucking to mastication, an important functional trigger for muscle. The mRNA and protein levels of CGRP increased in the MM and TG from postnatal day 10 (P10) to P20 in male mice. The protein levels of TRPV1 were almost constant in the TG from P10 to P20, in contrast to increases in the MM. The mRNA abundance of TRPV1 in the TG and MM was increased from P10 to P20. The localization of an antisense probe was used to count CGRP cell numbers and found to differentiate the ophthalmic, maxillary, and mandibular nerve divisions of the TG. In particular, the number of CGRP+ cells per 10,000 μm2 in the maxillary and mandibular divisions of the TG gradually changed from P10 to P20. The expression of CGRP and TRPV1 in the TG and MM and the patterns of expression of different MyHC isoforms were affected by changes in feeding during male mouse development.
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Affiliation(s)
- Hiroaki Kamata
- Division of Pediatric Dentistry, Nippon Dental University Graduate School of Life Dentistry, Tokyo, Japan.,Department of Pediatric Dentistry, School of Life Dentistry at Tokyo, Nippon Dental University, Tokyo, Japan
| | - Hiroyuki Karibe
- Department of Pediatric Dentistry, School of Life Dentistry at Tokyo, Nippon Dental University, Tokyo, Japan
| | - Iwao Sato
- Department of Anatomy, School of Life Dentistry at Tokyo, Nippon Dental University, Tokyo, Japan
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Liu XP, Wooltorton JRA, Gaboyard-Niay S, Yang FC, Lysakowski A, Eatock RA. Sodium channel diversity in the vestibular ganglion: NaV1.5, NaV1.8, and tetrodotoxin-sensitive currents. J Neurophysiol 2016; 115:2536-55. [PMID: 26936982 DOI: 10.1152/jn.00902.2015] [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: 09/22/2015] [Accepted: 02/02/2016] [Indexed: 01/02/2023] Open
Abstract
Firing patterns differ between subpopulations of vestibular primary afferent neurons. The role of sodium (NaV) channels in this diversity has not been investigated because NaV currents in rodent vestibular ganglion neurons (VGNs) were reported to be homogeneous, with the voltage dependence and tetrodotoxin (TTX) sensitivity of most neuronal NaV channels. RT-PCR experiments, however, indicated expression of diverse NaV channel subunits in the vestibular ganglion, motivating a closer look. Whole cell recordings from acutely dissociated postnatal VGNs confirmed that nearly all neurons expressed NaV currents that are TTX-sensitive and have activation midpoints between -30 and -40 mV. In addition, however, many VGNs expressed one of two other NaV currents. Some VGNs had a small current with properties consistent with NaV1.5 channels: low TTX sensitivity, sensitivity to divalent cation block, and a relatively negative voltage range, and some VGNs showed NaV1.5-like immunoreactivity. Other VGNs had a current with the properties of NaV1.8 channels: high TTX resistance, slow time course, and a relatively depolarized voltage range. In two NaV1.8 reporter lines, subsets of VGNs were labeled. VGNs with NaV1.8-like TTX-resistant current also differed from other VGNs in the voltage dependence of their TTX-sensitive currents and in the voltage threshold for spiking and action potential shape. Regulated expression of NaV channels in primary afferent neurons is likely to selectively affect firing properties that contribute to the encoding of vestibular stimuli.
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Affiliation(s)
- Xiao-Ping Liu
- Speech and Hearing Bioscience and Technology Program, Harvard-Massachusetts Institute of Technology Health Sciences and Technology Program, Cambridge, Massachusetts; Eaton-Peabody Laboratories, Massachusetts Eye and Ear, and Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts
| | | | - Sophie Gaboyard-Niay
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois
| | - Fu-Chia Yang
- Dana-Farber Cancer Institute, Boston, Massachusetts; Department of Neurobiology, Harvard Medical School, Boston, Massachusetts; and
| | - Anna Lysakowski
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois; Department of Otolaryngology-Head and Neck Surgery, University of Illinois at Chicago, Chicago, Illinois
| | - Ruth Anne Eatock
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, and Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts; Department of Neurobiology, Harvard Medical School, Boston, Massachusetts; and Department of Otolaryngology-Head and Neck Surgery, University of Illinois at Chicago, Chicago, Illinois
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7
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Han C, Vasylyev D, Macala LJ, Gerrits MM, Hoeijmakers JGJ, Bekelaar KJ, Dib-Hajj SD, Faber CG, Merkies ISJ, Waxman SG. The G1662S NaV1.8 mutation in small fibre neuropathy: impaired inactivation underlying DRG neuron hyperexcitability. J Neurol Neurosurg Psychiatry 2014; 85:499-505. [PMID: 24006052 DOI: 10.1136/jnnp-2013-306095] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Painful small fibre neuropathy (SFN) represents a significant public health problem, with no cause apparent in one-half of cases (termed idiopathic, I-SFN). Gain-of-function mutations of sodium channel NaV1.7 have recently been identified in nearly 30% of patients with biopsy-confirmed I-SFN. More recently, gain-of-function mutations of NaV1.8 have been found in patients with I-SFN. These NaV1.8 mutations accelerate recovery from inactivation, enhance the response to slow depolarisations, and enhance activation at the channel level, thereby producing hyperexcitability of small dorsal root ganglion (DRG) neurons, which include nociceptors, at the cellular level. Identification and functional profiling of additional NaV1.8 variants are necessary to determine the spectrum of changes in channel properties that underlie DRG neuron hyperexcitability in these patients. METHODS Two patients with painful SFN were evaluated by skin biopsy, quantitative sensory testing, nerve conduction studies, screening of genomic DNA for mutations in SCN9A and SCN10A and electrophysiological functional analysis. RESULTS A novel sodium channel NaV1.8 mutation G1662S was identified in both patients. Voltage-clamp analysis revealed that the NaV1.8/G1662S substitution impairs fast-inactivation, depolarising the midpoint (V1/2) by approximately 7 mV. Expression of G1662S mutant channels within DRG neurons rendered these cells hyperexcitable. CONCLUSIONS We report for the first time a mutation of NaV1.8 which impairs inactivation, in patients with painful I-SFN. Together with our earlier results, our observations indicate that an array of NaV1.8 mutations, which affect channel function in multiple ways, can contribute to the pathophysiology of painful peripheral neuropathy.
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Affiliation(s)
- Chongyang Han
- Department of Neurology, Yale University School of Medicine, , New Haven, Connecticut, USA
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Manteniotis S, Lehmann R, Flegel C, Vogel F, Hofreuter A, Schreiner BSP, Altmüller J, Becker C, Schöbel N, Hatt H, Gisselmann G. Comprehensive RNA-Seq expression analysis of sensory ganglia with a focus on ion channels and GPCRs in Trigeminal ganglia. PLoS One 2013; 8:e79523. [PMID: 24260241 PMCID: PMC3832644 DOI: 10.1371/journal.pone.0079523] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 10/02/2013] [Indexed: 12/14/2022] Open
Abstract
The specific functions of sensory systems depend on the tissue-specific expression of genes that code for molecular sensor proteins that are necessary for stimulus detection and membrane signaling. Using the Next Generation Sequencing technique (RNA-Seq), we analyzed the complete transcriptome of the trigeminal ganglia (TG) and dorsal root ganglia (DRG) of adult mice. Focusing on genes with an expression level higher than 1 FPKM (fragments per kilobase of transcript per million mapped reads), we detected the expression of 12984 genes in the TG and 13195 in the DRG. To analyze the specific gene expression patterns of the peripheral neuronal tissues, we compared their gene expression profiles with that of the liver, brain, olfactory epithelium, and skeletal muscle. The transcriptome data of the TG and DRG were scanned for virtually all known G-protein-coupled receptors (GPCRs) as well as for ion channels. The expression profile was ranked with regard to the level and specificity for the TG. In total, we detected 106 non-olfactory GPCRs and 33 ion channels that had not been previously described as expressed in the TG. To validate the RNA-Seq data, in situ hybridization experiments were performed for several of the newly detected transcripts. To identify differences in expression profiles between the sensory ganglia, the RNA-Seq data of the TG and DRG were compared. Among the differentially expressed genes (> 1 FPKM), 65 and 117 were expressed at least 10-fold higher in the TG and DRG, respectively. Our transcriptome analysis allows a comprehensive overview of all ion channels and G protein-coupled receptors that are expressed in trigeminal ganglia and provides additional approaches for the investigation of trigeminal sensing as well as for the physiological and pathophysiological mechanisms of pain.
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9
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Small-fiber neuropathy Nav1.8 mutation shifts activation to hyperpolarized potentials and increases excitability of dorsal root ganglion neurons. J Neurosci 2013; 33:14087-97. [PMID: 23986244 DOI: 10.1523/jneurosci.2710-13.2013] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Idiopathic small-fiber neuropathy (I-SFN), clinically characterized by burning pain in distal extremities and autonomic dysfunction, is a disorder of small-caliber nerve fibers of unknown etiology with limited treatment options. Functional variants of voltage-gated sodium channel Nav1.7, encoded by SCN9A, have been identified in approximately one-third of I-SFN patients. These variants render dorsal root ganglion (DRG) neurons hyperexcitable. Sodium channel Nav1.8, encoded by SCN10A, is preferentially expressed in small-diameter DRG neurons, and produces most of the current underlying the upstroke of action potentials in these neurons. We previously demonstrated two functional variants of Nav1.8 that either enhance ramp current or shift activation in a hyperpolarizing direction, and render DRG neurons hyperexcitable, in I-SFN patients with no mutations of SCN9A. We have now evaluated additional I-SFN patients with no mutations in SCN9A, and report a novel I-SFN-related Nav1.8 mutation I1706V in a patient with painful I-SFN. Whole-cell voltage-clamp recordings in small DRG neurons demonstrate that the mutation hyperpolarizes activation and the response to slow ramp depolarizations. However, it decreases fractional channels resistant to fast inactivation and reduces persistent currents. Current-clamp studies reveal that mutant channels decrease current threshold and increase the firing frequency of evoked action potentials within small DRG neurons. These observations suggest that the effects of this mutation on activation and ramp current are dominant over the reduced persistent current, and show that these pro-excitatory gating changes confer hyperexcitability on peripheral sensory neurons, which may contribute to pain in this individual with I-SFN.
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10
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Ono K, Xu S, Hitomi S, Inenaga K. Comparison of the electrophysiological and immunohistochemical properties of acutely dissociated and 1-day cultured rat trigeminal ganglion neurons. Neurosci Lett 2012; 523:162-6. [DOI: 10.1016/j.neulet.2012.06.069] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 06/22/2012] [Accepted: 06/23/2012] [Indexed: 01/21/2023]
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11
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Farmer C, Cox JJ, Fletcher EV, Woods CG, Wood JN, Schorge S. Splice variants of Na(V)1.7 sodium channels have distinct β subunit-dependent biophysical properties. PLoS One 2012; 7:e41750. [PMID: 22911851 PMCID: PMC3404004 DOI: 10.1371/journal.pone.0041750] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 06/25/2012] [Indexed: 12/13/2022] Open
Abstract
Genes encoding the α subunits of neuronal sodium channels have evolutionarily conserved sites of alternative splicing but no functional differences have been attributed to the splice variants. Here, using NaV1.7 as an exemplar, we show that the sodium channel isoforms are functionally distinct when co-expressed with β subunits. The gene, SCN9A, encodes the α subunit of the NaV1.7 channel, and contains both sites of alternative splicing that are highly conserved. In conditions where the intrinsic properties of the NaV1.7 splice variants were similar when expressed alone, co-expression of β1 subunits had different effects on channel availability that were determined by splicing at either site in the α subunit. While the identity of exon 5 determined the degree to which β1 subunits altered voltage-dependence of activation (P = 0.027), the length of exon 11 regulated how far β1 subunits depolarised voltage-dependence of inactivation (P = 0.00012). The results could have a significant impact on channel availability, for example with the long version of exon 11, the co-expression of β1 subunits could lead to nearly twice as large an increase in channel availability compared to channels containing the short version. Our data suggest that splicing can change the way that NaV channels interact with β subunits. Because splicing is conserved, its unexpected role in regulating the functional impact of β subunits may apply to multiple voltage-gated sodium channels, and the full repertoire of β subunit function may depend on splicing in α subunits.
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Affiliation(s)
- Clare Farmer
- UCL Institute of Neurology, Queen Square, London, United Kingdom
| | - James J. Cox
- UCL Wolfson Institute of Biomedical Research, London, United Kingdom
| | - E. V. Fletcher
- UCL Institute of Neurology, Queen Square, London, United Kingdom
| | - C. Geoffrey Woods
- Department of Medical Genetics, Cambridge Institute for Medical Research, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - John N. Wood
- UCL Wolfson Institute of Biomedical Research, London, United Kingdom
| | - Stephanie Schorge
- UCL Institute of Neurology, Queen Square, London, United Kingdom
- * E-mail:
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Siniscalchi A, Gallelli L, Avenoso T, Squillace A, De Sarro G. Effects of Carbamazepine/Oxycodone Coadministration in the Treatment of Trigeminal Neuralgia. Ann Pharmacother 2011; 45:e33. [DOI: 10.1345/aph.1q013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE: To report on a patient with trigeminal neuralgia who responded positively to combined carbamazepine/oxycodone treatment. CASE SUMMARY: A 48-year-old woman with a 4-month history of left facial pain consisting of episodes lasting less than 5 minutes was brought to our institution for clinical evaluation. Clinical, laboratory, and neuroradiologic findings led to a diagnosis of idiopathic trigeminal neuralgia. Carbamazepine treatment was started at 200 mg every 12 hours and increased at discharge to 300 mg every 8 hours. Two weeks later the patient was readmitted with trigeminal neuralgia symptoms that had persisted since the previous admission, although they had decreased in intensity. Carbamazepine was reduced to 200 mg every 8 hours and oxycodone 5 mg every 12 hours was added to the treatment regimen, with a complete resolution of pain within 7 days. DISCUSSION: Pathophysiological mechanisms involved in both the genesis and the maintenance of trigeminal neuralgia have not yet been defined. Several hypotheses could explain this disorder, ranging from peripheral neural ectopic pacemaker to central disinhibition. Both the interruption of the sodium channel and the modulation of both κ-and μ-opioid receptors contributed to antinociceptive effects in trigeminal neuralgia. CONCLUSIONS: Treatment with a combination of carbamazepine, a sodium channel blocker, and oxycodone, a mixed κ-and μ-opioid receptor agonist, may be useful in alleviating symptoms of trigeminal neuralgia.
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Affiliation(s)
- Antonio Siniscalchi
- Antonio Siniscalchi MD, Department of Neuroscience, Neurology Division, “Annunziata” Hospital, Cosenza, Italy
| | - Luca Gallelli
- Luca Gallelli MD PhD, Chair of Pharmacology, Department of Experimental and Clinical Medicine, School of Medicine, University Magna Graecia of Catanzaro; Clinical Pharmacology Unit, Mater Domini University Hospital, Catanzaro, Italy
| | - Tiziana Avenoso
- Tiziana Avenoso, Nurse, Department of Experimental and Clinical Medicine, School of Medicine, University Magna Graecia of Catanzaro
| | - Aida Squillace
- Aida Squillace MD, Chair of Pharmacology, Department of Experimental and Clinical Medicine, School of Medicine, University Magna Graecia of Catanzaro; Clinical Pharmacology Unit, Mater Domini University Hospital
| | - Giovambattista De Sarro
- Giovambattista De Sarro MD, Chair of Pharmacology, Department of Experimental and Clinical Medicine, School of Medicine, University Magna Graecia of Catanzaro; Clinical Pharmacology Unit, Mater Domini University Hospital, Catanzaro, Italy
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