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Miller PA, Williams-Ikhenoba JG, Sankhe AS, Hoffe BH, Chee MJ. Neuroanatomical, electrophysiological, and morphological characterization of melanin-concentrating hormone cells coexpressing cocaine- and amphetamine-regulated transcript. J Comp Neurol 2024; 532:e25588. [PMID: 38335050 DOI: 10.1002/cne.25588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 12/18/2023] [Accepted: 01/09/2024] [Indexed: 02/12/2024]
Abstract
Melanin-concentrating hormone (MCH) cells in the hypothalamus regulate fundamental physiological functions like energy balance, sleep, and reproduction. This diversity may be ascribed to the neurochemical heterogeneity among MCH cells. One prominent subpopulation of MCH cells coexpresses cocaine- and amphetamine-regulated transcript (CART), and as MCH and CART can have opposing actions, MCH/CART+ and MCH/CART- cells may differentially modulate behavioral outcomes. However, it is not known if there are differences in the cellular properties underlying their functional differences; thus, we compared the neuroanatomical, electrophysiological, and morphological properties of MCH cells in male and female Mch-cre;L10-Egfp reporter mice. Half of MCH cells expressed CART and were most prominent in the medial hypothalamus. Whole-cell patch-clamp recordings revealed differences in their passive and active membrane properties in a sex-dependent manner. Female MCH/CART+ cells had lower input resistances, but male cells largely differed in their firing properties. All MCH cells increased firing when stimulated, but their firing frequency decreases with sustained stimulation. MCH/CART+ cells showed stronger spike rate adaptation than MCH/CART- cells. The kinetics of excitatory events at MCH cells also differed by cell type, as the rising rate of excitatory events was slower at MCH/CART+ cells. By reconstructing the dendritic arborization of our recorded cells, we found no sex differences, but male MCH/CART+ cells had less dendritic length and fewer branch points. Overall, distinctions in topographical division and cellular properties between MCH cells add to their heterogeneity and help elucidate their response to stimuli or effect on modulating their respective neural networks.
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Affiliation(s)
| | | | - Aditi S Sankhe
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Brendan H Hoffe
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Melissa J Chee
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
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2
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Contributions of Na V1.8 and Na V1.9 to excitability in human induced pluripotent stem-cell derived somatosensory neurons. Sci Rep 2021; 11:24283. [PMID: 34930944 PMCID: PMC8688473 DOI: 10.1038/s41598-021-03608-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 12/02/2021] [Indexed: 12/13/2022] Open
Abstract
The inhibition of voltage-gated sodium (NaV) channels in somatosensory neurons presents a promising novel modality for the treatment of pain. However, the precise contribution of these channels to neuronal excitability, the cellular correlate of pain, is unknown; previous studies using genetic knockout models or pharmacologic block of NaV channels have identified general roles for distinct sodium channel isoforms, but have never quantified their exact contributions to these processes. To address this deficit, we have utilized dynamic clamp electrophysiology to precisely tune in varying levels of NaV1.8 and NaV1.9 currents into induced pluripotent stem cell-derived sensory neurons (iPSC-SNs), allowing us to quantify how graded changes in these currents affect different parameters of neuronal excitability and electrogenesis. We quantify and report direct relationships between NaV1.8 current density and action potential half-width, overshoot, and repetitive firing. We additionally quantify the effect varying NaV1.9 current densities have on neuronal membrane potential and rheobase. Furthermore, we examined the simultaneous interplay between NaV1.8 and NaV1.9 on neuronal excitability. Finally, we show that minor biophysical changes in the gating of NaV1.8 can render human iPSC-SNs hyperexcitable, in a first-of-its-kind investigation of a gain-of-function NaV1.8 mutation in a human neuronal background.
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Abstract
The function of the nervous system in conveying and processing information necessary to interact with the environment confers unique aspects on how the expression of genes in neurons is regulated. Three salient factors are that (1) neurons are the largest and among the most morphologically complex of all cells, with strict polarity, subcellular compartmentation, and long-distant transport of gene products, signaling molecules, and other materials; (2) information is coded in the temporal firing pattern of membrane depolarization; and (3) neurons must maintain a stable homeostatic level of activation to function so stimuli do not normally drive intracellular signaling to steady state. Each of these factors can require special methods of analysis differing from approaches used in non-neuronal cells. This review considers these three aspects of neuronal gene expression and the current approaches being used to analyze these special features of how the neuronal transcriptome is modulated by action potential firing.
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Affiliation(s)
- Philip R. Lee
- Nervous System Development and Plasticity Section, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - R. Douglas Fields
- Nervous System Development and Plasticity Section, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA
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4
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Goaillard JM, Marder E. Ion Channel Degeneracy, Variability, and Covariation in Neuron and Circuit Resilience. Annu Rev Neurosci 2021; 44:335-357. [PMID: 33770451 DOI: 10.1146/annurev-neuro-092920-121538] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The large number of ion channels found in all nervous systems poses fundamental questions concerning how the characteristic intrinsic properties of single neurons are determined by the specific subsets of channels they express. All neurons display many different ion channels with overlapping voltage- and time-dependent properties. We speculate that these overlapping properties promote resilience in neuronal function. Individual neurons of the same cell type show variability in ion channel conductance densities even though they can generate reliable and similar behavior. This complicates a simple assignment of function to any conductance and is associated with variable responses of neurons of the same cell type to perturbations, deletions, and pharmacological manipulation. Ion channel genes often show strong positively correlated expression, which may result from the molecular and developmental rules that determine which ion channels are expressed in a given cell type.
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Affiliation(s)
| | - Eve Marder
- Volen Center and Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA;
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Iacobas DA, Iacobas S, Lee PR, Cohen JE, Fields RD. Coordinated Activity of Transcriptional Networks Responding to the Pattern of Action Potential Firing in Neurons. Genes (Basel) 2019; 10:genes10100754. [PMID: 31561430 PMCID: PMC6826514 DOI: 10.3390/genes10100754] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 09/17/2019] [Accepted: 09/20/2019] [Indexed: 12/13/2022] Open
Abstract
Transcriptional responses to the appropriate temporal pattern of action potential firing are essential for long-term adaption of neuronal properties to the functional activity of neural circuits and environmental experience. However, standard transcriptome analysis methods can be too limited in identifying critical aspects that coordinate temporal coding of action potential firing with transcriptome response. A Pearson correlation analysis was applied to determine how pairs of genes in the mouse dorsal root ganglion (DRG) neurons are coordinately expressed in response to stimulation producing the same number of action potentials by two different temporal patterns. Analysis of 4728 distinct gene-pairs related to calcium signaling, 435,711 pairs of transcription factors, 820 pairs of voltage-gated ion channels, and 86,862 pairs of calcium signaling genes with transcription factors indicated that genes become coordinately activated by distinct action potential firing patterns and this depends on the duration of stimulation. Moreover, a measure of expression variance revealed that the control of transcripts abundances is sensitive to the pattern of stimulation. Thus, action potentials impact intracellular signaling and the transcriptome in dynamic manner that not only alter gene expression levels significantly (as previously reported) but also affects the control of their expression fluctuations and profoundly remodel the transcriptional networks.
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Affiliation(s)
- Dumitru A Iacobas
- Personalized Genomics Laboratory, Center for Computational Systems Biology, Prairie View A&M University, Prairie View, TX 77446, USA.
- DP Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Sanda Iacobas
- Department of Pathology, New York Medical College, Valhalla, NY 10595, USA.
| | - Philip R Lee
- Section on Nervous System Development and Plasticity, the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), NIH, Bethesda, MD 20892, USA.
| | - Jonathan E Cohen
- Division of Medical Imaging Products, U.S. Food and Drug Administration, Silver Spring, 20993 MD, USA.
| | - R Douglas Fields
- Section on Nervous System Development and Plasticity, the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), NIH, Bethesda, MD 20892, USA.
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Mao W, Zhang J, Körner H, Jiang Y, Ying S. The Emerging Role of Voltage-Gated Sodium Channels in Tumor Biology. Front Oncol 2019; 9:124. [PMID: 30895169 PMCID: PMC6414428 DOI: 10.3389/fonc.2019.00124] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 02/12/2019] [Indexed: 11/13/2022] Open
Abstract
Voltage-gated sodium channels (VGSCs) are transmembrane proteins which function as gates that control the flux of ions across the cell membrane. They are key ion channels for action potentials in excitable tissues and have important physiological functions. Abnormal function of VGSCs will lead to dysfunction of the body and trigger a variety of diseases. Various studies have demonstrated the participation of VGSCs in the progression of different tumors, such as prostate cancer, cervical cancer, breast cancer, and others, linking VGSC to the invasive capacity of tumor cells. However, it is still unclear whether the VGSC regulate the malignant biological behavior of tumors. Therefore, this paper systematically addresses the latest research progress on VGSCs subunits and tumors and the underlying mechanisms, and it summarizes the potential of VGSCs subunits to serve as potential targets for tumor diagnosis and treatment.
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Affiliation(s)
- Weijia Mao
- Key Laboratory of Oral Disease Research of Anhui Province, College & Hospital of Stomatology, Anhui Medical University, Hefei, China.,Department of Immunology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Jie Zhang
- Key Laboratory of Oral Disease Research of Anhui Province, College & Hospital of Stomatology, Anhui Medical University, Hefei, China.,Department of Immunology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Heinrich Körner
- Key Laboratory of Anti-inflammatory and Immunopharmacology, Institute of Clinical Pharmacology, Anhui Medical University, Hefei, China.,Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
| | - Yong Jiang
- Key Laboratory of Oral Disease Research of Anhui Province, College & Hospital of Stomatology, Anhui Medical University, Hefei, China
| | - Songcheng Ying
- Department of Immunology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
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Vancamp T, Levy RM, Peña I, Pajuelo A. Relevant Anatomy, Morphology, and Implantation Techniques of the Dorsal Root Ganglia at the Lumbar Levels. Neuromodulation 2017; 20:690-702. [PMID: 28895256 DOI: 10.1111/ner.12651] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 06/30/2017] [Accepted: 07/17/2017] [Indexed: 12/30/2022]
Abstract
OBJECTIVES While dorsal root ganglion (DRG) stimulation has been available in Europe and Australia for the past five years and in the United States for the past year, there are no published details concerning the optimal procedures for DRG lead implantation. MATERIALS AND METHODS We describe several techniques that can be applied to implant cylindrical leads over the DRG, highlighting some tips and tricks according to our experiences. Focus is mainly shifted toward implantations in the lumbar area. We furthermore give some insights in the results we experienced in Spain as well as some worldwide numbers. IMPLANT TECHNIQUES AND RESULTS A 14-gauge needle is placed using a "2-Level Technique (2-LT)" or exceptionally a "1-Level Technique (1-LT)" or a "Primary- or Secondary Technique" at the level of L5. The delivery sheath, loaded with the lead, is advanced toward the targeted neural foramen. The lead is placed over the dorsal aspect of the DRG. A strain relief loop is created in the epidural space. Sheath and needle are retracted and the lead is secured using an anchor or anchorless technique. In Spain, 87.2% (N = 78) of the selected patients have been successfully implanted. Seven (8.9%) had a negative trial and three (4.2%) were explanted. Average VAS score decreased from 8.8 to 3.3 and on average 94.5% of the pain area was covered. In our center's subjects (N = 47 patients, 60.3% of all implanted patients in Spain), VAS scores decreased from an average of 8.8-1.7 and pain coverage averaged 96.4%. We used an average of 1.8 electrodes. Worldwide more than 4000 permanent cases have been successfully performed. CONCLUSIONS We present implantation techniques whereby a percutaneous lead is placed over the DRG through the use of a special designed delivery sheath. Further investigation of the safety, efficacy, and sustainability of clinical outcomes using these devices is warranted.
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Affiliation(s)
- Tim Vancamp
- BRAI2N, St. Augustinus Hospital, Wilrijk, Belgium
| | | | - Isaac Peña
- Department of Anesthesiology and Pain Management, Virgen del Rocio University Hospital, Sevilla, Spain
| | - Antonio Pajuelo
- Department of Anesthesiology and Pain Management, Virgen del Rocio University Hospital, Sevilla, Spain
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8
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Zhong XP, Chen YX, Li ZY, Shen ZW, Kong KM, Wu RH. Cervical spinal functional magnetic resonance imaging of the spinal cord injured patient during electrical stimulation. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2017; 26:71-77. [PMID: 27311305 DOI: 10.1007/s00586-016-4646-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 05/31/2016] [Accepted: 06/01/2016] [Indexed: 02/05/2023]
Abstract
PURPOSE To evaluate the spatial distribution and signal intensity changes following spinal cord activation in patients with spinal cord injury. METHODS This study used spinal functional magnetic resonance imaging (fMRI) based on signal enhancement by extra-vascular water protons (SEEP) to assess elicited responses during subcutaneous electrical stimulation at the right elbow and right thumb in the cervical spinal cord. RESULTS Seven healthy volunteers and seven patients with cervical spinal cord injury (SCI) were included in this study. Significant functional activation was observed mainly in the right side of the spinal cord at the level of the C5-C6 cervical vertebra in both the axial and sagittal planes. A higher percentage of signal changes (4.66 ± 2.08 % in injured subjects vs. 2.78 ± 1.66 % in normal) and more average activation voxels (4.69 ± 2.59 in injured subjects vs. 2.56 ± 1.13 in normal subject) in axial plane at the C5-C6 cervical vertebra with a statistically significant difference. The same trends were observed in the sagittal plane with higher percentage of signal changes and more average activation voxels, though no statistically significant difference compared with the control group. CONCLUSIONS Spinal SEEP fMRI is a powerful noninvasive method for the study of local neuronal activation in the human spinal cord, which may be of clinical value for evaluating the effectiveness of interventions aimed at promoting recovery of function using electrical stimulation.
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Affiliation(s)
- Xiao-Ping Zhong
- Department of Surgery, 2nd Affiliated Hospital of Shantou University Medical College, Shantou, 515041, Guangdong, China
| | - Ye-Xi Chen
- Department of Surgery, 2nd Affiliated Hospital of Shantou University Medical College, Shantou, 515041, Guangdong, China.
| | - Zhi-Yang Li
- Department of Surgery, 2nd Affiliated Hospital of Shantou University Medical College, Shantou, 515041, Guangdong, China
| | - Zhi-Wei Shen
- Department of Medical Imaging, 2nd Affiliated Hospital of Shantou University Medical College, Shantou, 515041, Guangdong, China.
| | - Kang-Mei Kong
- Department of Surgery, 2nd Affiliated Hospital of Shantou University Medical College, Shantou, 515041, Guangdong, China
| | - Ren-Hua Wu
- Department of Medical Imaging, 2nd Affiliated Hospital of Shantou University Medical College, Shantou, 515041, Guangdong, China
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9
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Bremer N, Ruby J, Weyker PD, Webb CAJ. Neuromodulation: a focus on dorsal root ganglion stimulation. Pain Manag 2016; 6:205-9. [PMID: 26975305 DOI: 10.2217/pmt-2015-0013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Nicholas Bremer
- Department of Anesthesiology, Columbia University College of Physicians & Surgeons, New York, NY, USA
| | - Jordan Ruby
- Department of Anesthesiology, Perioperative & Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Paul D Weyker
- Department of Anesthesiology, Division of Pain Medicine, Columbia University Medical Center, New York, NY, USA.,Department of Anesthesiology, Division of Critical Care, Columbia University Medical Center, New York, NY, USA
| | - Christopher A J Webb
- Department of Anesthesiology, Division of Pain Medicine, Columbia University Medical Center, New York, NY, USA.,Department of Anesthesiology, Division of Regional Anesthesia, Columbia University Medical Center, New York, NY, USA
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10
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Krames ES. The Dorsal Root Ganglion in Chronic Pain and as a Target for Neuromodulation: A Review. Neuromodulation 2014; 18:24-32; discussion 32. [DOI: 10.1111/ner.12247] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 11/08/2013] [Accepted: 02/04/2014] [Indexed: 11/29/2022]
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11
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Fraser SP, Ozerlat-Gunduz I, Brackenbury WJ, Fitzgerald EM, Campbell TM, Coombes RC, Djamgoz MBA. Regulation of voltage-gated sodium channel expression in cancer: hormones, growth factors and auto-regulation. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130105. [PMID: 24493753 PMCID: PMC3917359 DOI: 10.1098/rstb.2013.0105] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Although ion channels are increasingly being discovered in cancer cells in vitro and in vivo, and shown to contribute to different aspects and stages of the cancer process, much less is known about the mechanisms controlling their expression. Here, we focus on voltage-gated Na+ channels (VGSCs) which are upregulated in many types of carcinomas where their activity potentiates cell behaviours integral to the metastatic cascade. Regulation of VGSCs occurs at a hierarchy of levels from transcription to post-translation. Importantly, mainstream cancer mechanisms, especially hormones and growth factors, play a significant role in the regulation. On the whole, in major hormone-sensitive cancers, such as breast and prostate cancer, there is a negative association between genomic steroid hormone sensitivity and functional VGSC expression. Activity-dependent regulation by positive feedback has been demonstrated in strongly metastatic cells whereby the VGSC is self-sustaining, with its activity promoting further functional channel expression. Such auto-regulation is unlike normal cells in which activity-dependent regulation occurs mostly via negative feedback. Throughout, we highlight the possible clinical implications of functional VGSC expression and regulation in cancer.
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Affiliation(s)
- Scott P Fraser
- Neuroscience Solutions to Cancer Research Group, Department of Life Sciences, Imperial College London, , South Kensington Campus, London SW7 2AZ, UK
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12
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Tan AM. Emerging evidence for P body function in the peripheral nervous system. Neurosci Lett 2013; 563:166-8. [PMID: 24211685 DOI: 10.1016/j.neulet.2013.10.059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 10/29/2013] [Indexed: 12/27/2022]
Affiliation(s)
- Andrew M Tan
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA; Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA.
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13
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Ren L, Fang YN, Zhang AW, Li XL, Wang XJ, Yin Z, Miao JY. Effect of electroacupuncture on the expression of Nav1·1 in rat after acute cerebral ischemia. Neurol Res 2013; 32:763-9. [DOI: 10.1179/016164109x12445616596481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Ren L, Wang YK, Fang YN, Zhang AW, Li XL. Effect of electroacupuncture therapy on the expression of Na(v)1.1 and Na(v)1.6 in rat after acute cerebral ischemia. Neurol Res 2013; 32:1110-6. [DOI: 10.1179/016164110x12700393823453] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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15
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Hronik-Tupaj M, Raja WK, Tang-Schomer M, Omenetto FG, Kaplan DL. Neural responses to electrical stimulation on patterned silk films. J Biomed Mater Res A 2013; 101:2559-72. [PMID: 23401351 DOI: 10.1002/jbm.a.34565] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 12/15/2012] [Accepted: 12/18/2012] [Indexed: 12/21/2022]
Abstract
Peripheral nerve injury is a critical issue for patients with trauma. Following injury, incomplete axon regeneration or misguided axon innervation into tissue will result in loss of sensory and motor functions. The objective of this study was to examine axon outgrowth and axon alignment in response to surface patterning and electrical stimulation. To accomplish our objective, metal electrodes with dimensions of 1.5 mm × 4 cm, were sputter coated onto micropatterned silk protein films, with surface grooves 3.5 μm wide × 500 nm deep. P19 neurons were seeded on the patterned electronic silk films and stimulated at 120 mV, 1 kHz, for 45 min each day for 7 days. Responses were compared with neurons on flat electronic silk films, patterned silk films without stimulation, and flat silk films without stimulation. Significant alignment was found on the patterned film groups compared with the flat film groups. Axon outgrowth was greater (p < 0.05) on electronic films on days 5 and 7 compared with the unstimulated groups. In conclusion, electrical stimulation, at 120 mV, 1 kHz, for 45 min daily, in addition to surface patterning, of 3.5 μm wide × 500 nm deep grooves, offered control of nerve axon outgrowth and alignment.
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Affiliation(s)
- Marie Hronik-Tupaj
- Department of Biomedical Engineering, Science & Technology Center, Tufts University, Medford, Massachusetts 02155, USA
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Boada MD, Gutierrez S, Houle T, Eisenach JC, Ririe DG. Developmental differences in peripheral glabrous skin mechanosensory nerve receptive field and intracellular electrophysiologic properties: phenotypic characterization in infant and juvenile rats. Int J Dev Neurosci 2011; 29:847-54. [PMID: 21856407 PMCID: PMC3381879 DOI: 10.1016/j.ijdevneu.2011.08.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 08/05/2011] [Accepted: 08/06/2011] [Indexed: 11/17/2022] Open
Abstract
Developmental differences in peripheral neuron characteristics and functionality exist. Direct measurement of active and passive electrophysiologic and receptive field characteristics of single mechanosensitive neurons in glabrous skin was performed and phenotypic characterization of fiber subtypes was applied to analyze developmental differences in peripheral mechanosensitive afferents. After Institutional approval, male Sprague-Dawley infant (P7: postnatal day 7) and juvenile (P28) rats were anesthetized and single cell intracellular electrophysiology was performed in the dorsal root ganglion (DRG) soma of mechanosensitive cells with receptive field (RF) in the glabrous skin of the hindpaw. Passive and active electrical properties of the cells and RF size and characteristics determined. Fiber subtype classification was performed and developmental differences in fiber subtype properties analyzed. RF size was smaller at P7 for both low and high threshold mechanoreceptor (LTMR and HTMR) with no differences between A- and C-HTMR (AHTMR and CHTMR). The RF size was also correlated to anatomic location on glabrous skin, toes having smaller RF. Conduction velocity (CV) was adequate at P28 for AHTMR and CHTMR classification, but not at P7. Only width of the action potential at half height (D50) was significantly different between HTMR at P7, while D50, CV and amplitude of the AP were significant for HTMR at P28. RF size is determined in part by the RF distribution of the peripheral neuron. Developmental differences in RF size occur with larger RF sizes occurring in younger animals. This is consistent with RF size differences determined by measuring RF in the spinal cord, except the peripheral RF is much smaller, more refined, and in some cases pinpoint. Developmental differences make CV alone unreliable for neuron classification. Utilizing integration of all measured parameters allows classification of neurons into subtypes even at the younger ages. This will prove important in understanding changes that occur in the peripheral sensory afferents in the face of ongoing development and injury early in life.
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Affiliation(s)
- M Danilo Boada
- Department of Anesthesiology, Wake Forest School of Medicine, Winston-Salem, NC 27157-1009, USA.
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Castañeda-Corral G, Jimenez-Andrade JM, Bloom AP, Taylor RN, Mantyh WG, Kaczmarska MJ, Ghilardi JR, Mantyh PW. The majority of myelinated and unmyelinated sensory nerve fibers that innervate bone express the tropomyosin receptor kinase A. Neuroscience 2011; 178:196-207. [PMID: 21277945 DOI: 10.1016/j.neuroscience.2011.01.039] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 01/16/2011] [Accepted: 01/20/2011] [Indexed: 12/13/2022]
Abstract
Although skeletal pain is a leading cause of chronic pain and disability, relatively little is known about the specific populations of nerve fibers that innervate the skeleton. Recent studies have reported that therapies blocking nerve growth factor (NGF) or its cognate receptor, tropomyosin receptor kinase A (TrkA) are efficacious in attenuating skeletal pain. A potential factor to consider when assessing the analgesic efficacy of targeting NGF-TrkA signaling in a pain state is the fraction of NGF-responsive TrkA+ nociceptors that innervate the tissue from which the pain is arising, as this innervation and the analgesic efficacy of targeting NGF-TrkA signaling may vary considerably from tissue to tissue. To explore this in the skeleton, tissue slices and whole mount preparations of the normal, adult mouse femur were analyzed using immunohistochemistry and confocal microscopy. Analysis of these preparations revealed that 80% of the unmyelinated/thinly myelinated sensory nerve fibers that express calcitonin gene-related peptide (CGRP) and innervate the periosteum, mineralized bone and bone marrow also express TrkA. Similarly, the majority of myelinated sensory nerve fibers that express neurofilament 200 kDa (NF200) which innervate the periosteum, mineralized bone and bone marrow also co-express TrkA. In the normal femur, the relative density of CGRP+, NF200+ and TrkA+ sensory nerve fibers per unit volume is: periosteum>bone marrow>mineralized bone>cartilage with the respective relative densities being 100:2:0.1:0. The observation that the majority of sensory nerve fibers innervating the skeleton express TrkA+, may in part explain why therapies that block NGF/TrkA pathway are highly efficacious in attenuating skeletal pain.
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Affiliation(s)
- G Castañeda-Corral
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
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Islamov RR, Tyapkina OV, Eremeev AA, Shaymardanova GF, Chakkaeva EA, Kozlovskaya IB, Nikolsky EE. Possible specialization of motoneuron axonal compartments in synthesis of particular proteins. Biophysics (Nagoya-shi) 2010. [DOI: 10.1134/s0006350910050106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Rukwied R, Schley M, Forsch E, Obreja O, Dusch M, Schmelz M. Nerve growth factor-evoked nociceptor sensitization in pig skin in vivo. J Neurosci Res 2010; 88:2066-72. [PMID: 20143422 DOI: 10.1002/jnr.22351] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Peripheral sensitization of skin nociceptors by nerve growth factor (NGF) was explored in pig skin in vivo. As an objective output measure, the area of axon-reflex-mediated erythema was assessed upon mechanical, thermal, chemical, and electrical stimuli delivered at 1, 3, and 7 days after i.d. injection of 1 microg NGF into the pig's back skin (n = 8). Pretreatment with NGF provoked a sensitization to mechanical (600 mN), thermal (10 sec 49 degrees C) and chemical (15 microl, pH 3) stimuli that lasted for 7 days. No sensitization, however, was found in response to weak mechanical (100 mN), weak thermal (10 sec 45 degrees C), or electrical stimuli. Irrespective of the skin pretreatment (NGF or PBS vehicle control), the area of electrically induced erythema decreased upon repetition (days 1-7) by 70% (P < 0.05). Sensitization of sensory endings by NGF upon mechanical, heat, and chemical stimuli suggests recruitment of sensory transducer molecules [e.g., TRPV1, acid-sensing ion channels (ASICs)]. In contrast, the gradual decrease in electrically induced erythema over 7 days might be attributable to axonal desensitization and possibly activity-dependent down-regulation of sodium channels. Thus, long-lasting sensitization processes of nociceptor endings or axonal sodium channel desensitization mechanisms can be explored in the pig as a translational experimental animal model.
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Affiliation(s)
- Roman Rukwied
- University Clinics of Anaesthesiology and Intensive Care Medicine, University Medicine Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany.
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Abstract
Peripheral nerve injury causes neuropathic pain, which is characterized by the paradoxical sensations of positive and negative symptoms. Clinically, negative signs are frequently observed; however, their underlying molecular mechanisms are largely unknown. Dysfunction of C-fibers is assumed to underlie negative symptoms and is accompanied by long-lasting downregulation of Na(v)1.8 sodium channel and mu-opioid receptor (MOP) in the dorsal root ganglion (DRG). In the present study, we found that nerve injury upregulates neuron-restrictive silencer factor (NRSF) expression in the DRG neurons mediated through epigenetic mechanisms. In addition, chromatin immunoprecipitation analysis revealed that nerve injury promotes NRSF binding to the neuron-restrictive silencer element within MOP and Na(v)1.8 genes, thereby causing epigenetic silencing. Furthermore, NRSF knockdown significantly blocked nerve injury-induced downregulations of MOP and Na(v)1.8 gene expressions, C-fiber hypoesthesia, and the losses of peripheral morphine analgesia and Na(v)1.8-selective blocker-induced hypoesthesia. Together, these data suggest that NRSF causes pathological and pharmacological dysfunction of C-fibers, which underlies the negative symptoms in neuropathic pain.
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Protein–protein interactions involving voltage-gated sodium channels: Post-translational regulation, intracellular trafficking and functional expression. Int J Biochem Cell Biol 2009; 41:1471-81. [DOI: 10.1016/j.biocel.2009.01.016] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Revised: 01/23/2009] [Accepted: 01/26/2009] [Indexed: 01/06/2023]
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Devor M. Ectopic discharge in Abeta afferents as a source of neuropathic pain. Exp Brain Res 2009; 196:115-28. [PMID: 19242687 DOI: 10.1007/s00221-009-1724-6] [Citation(s) in RCA: 275] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Accepted: 01/22/2009] [Indexed: 12/25/2022]
Abstract
Ectopic discharge in axotomized dorsal root ganglion neurons is a key driver of neuropathic pain. However, the bulk of this activity is generated and carried centrally in large diameter myelinated Abeta afferents, a cell type that normally signals touch and vibration sense. Evidence is considered suggesting that following axotomy, Abeta afferents undergo a change in their electrical characteristics and also in the neurotransmitter complement that they express. This dual phenotypic switching renders them capable of (1) directly driving postsynaptic pain signaling pathways in the spinal cord, and (2) triggering and maintaining central sensitization.
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Affiliation(s)
- Marshall Devor
- Department of Cell and Developmental Biology, Institute of Life Sciences and Center for Research on Pain, Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
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Boroujerdi A, Kim HK, Lyu YS, Kim DS, Figueroa KW, Chung JM, Luo ZD. Injury discharges regulate calcium channel alpha-2-delta-1 subunit upregulation in the dorsal horn that contributes to initiation of neuropathic pain. Pain 2008; 139:358-366. [PMID: 18571852 PMCID: PMC2613852 DOI: 10.1016/j.pain.2008.05.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 04/09/2008] [Accepted: 05/06/2008] [Indexed: 11/24/2022]
Abstract
Previous studies have shown that peripheral nerve injury in rats induces increased expression of the voltage gated calcium channel (VGCC) alpha-2-delta-1 subunit (Ca v alpha2 delta1) in spinal dorsal horn and sensory neurons in dorsal root ganglia (DRG) that correlates to established neuropathic pain states. To determine if injury discharges trigger Ca v alpha2 delta1 induction that contributes to neuropathic pain initiation, we examined allodynia onset and Ca v alpha2 delta1 levels in DRG and spinal dorsal horn of spinal nerve ligated rats after blocking injury induced neural activity with a local brief application of lidocaine on spinal nerves before the ligation. The lidocaine pretreatment blocked ligation-induced discharges in a dose-dependent manner. Similar pretreatment with the effective concentration of lidocaine diminished injury-induced increases of the Ca v alpha2 delta1 in DRG and abolished that in spinal dorsal horn specifically, and resulted in a delayed onset of tactile allodynia post-injury. Both dorsal horn Ca v alpha2 delta1 upregulation and tactile allodynia in the lidocaine pretreated rats returned to levels similar to that in saline pretreated controls 2 weeks post the ligation injury. In addition, preemptive intrathecal Ca v alpha2 delta1 antisense treatments blocked concurrently injury-induced allodynia onset and Ca v alpha2 delta1 upregulation in dorsal spinal cord. These findings indicate that injury induced discharges regulate Ca v alpha2 delta1 expression in the spinal dorsal horn that is critical for neuropathic allodynia initiation. Thus, preemptive blockade of injury-induced neural activity or Ca v alpha2 delta1 upregulation may be a beneficial option in neuropathic pain management.
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Affiliation(s)
- Amin Boroujerdi
- Department of Pharmacology, University of California Irvine, Irvine, CA 92697
| | - Hee Kee Kim
- Department of Anesthesiology, University of California Irvine, Irvine, CA 92697
| | - Yeoung Su Lyu
- Department of Anesthesiology, University of California Irvine, Irvine, CA 92697
| | - Doo-Sik Kim
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555
| | | | - Jin Mo Chung
- Department of Anesthesiology, University of California Irvine, Irvine, CA 92697
| | - Z. David Luo
- Department of Pharmacology, University of California Irvine, Irvine, CA 92697
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555
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Electrophysiologic characteristics of large neurons in dorsal root ganglia during development and after hind paw incision in the rat. Anesthesiology 2008; 109:111-7. [PMID: 18580180 DOI: 10.1097/aln.0b013e31817c1ab9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Withdrawal thresholds in the paw are lower in younger animals, and incision further reduces these thresholds. The authors hypothesized that these differences result in part from changes in intrinsic electrophysiologic properties of large neurons. METHODS Using isolated whole dorsal root ganglion, current clamping was performed to determine the electrophysiologic properties of large neurons before and after incision in animals aged 1 and 4 weeks. Mechanical withdrawal thresholds were used to follow paw sensitivity. RESULTS After paw incision, withdrawal thresholds decreased to a similar degree at both ages, but returned to control threshold at 72 h only in the 1-week-old animals. The resting membrane potential was less negative and the rheobase and the resistance of the membrane were lower at baseline in the 1-week-old animals (P < 0.05). After incision, the membrane potential became more depolarized and the rheobase was less in both ages. These changes remained 72 h after the incision in both ages. CONCLUSION These findings suggest that lower mechanical thresholds in the younger animals may be partially attributed to the intrinsic electrophysiologic properties of the larger-diameter afferent neurons. The lack of resolution of the electrophysiologic changes in the young despite the resolution of the withdrawal response suggests that continued input from large fibers into the central nervous system may occur at this age despite the apparent resolution of behavioral changes. Further studies are needed to determine the etiology of these differences, their impact in the central nervous system, and whether theses changes can be prevented.
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25
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Hobbs KH, Hooper SL. Using complicated, wide dynamic range driving to develop models of single neurons in single recording sessions. J Neurophysiol 2008; 99:1871-83. [PMID: 18256169 DOI: 10.1152/jn.00032.2008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Neuron models are typically built by measuring individually, for each membrane conductance, its parameters (e.g., half-maximal voltages) and maximal conductance value (g(max)). However, neurons have extended morphologies with nonuniform conductance distributions, whereas models generally contain at most a few compartments. Both the original conductance measurements and the models therefore unavoidably contain error due to the electrical filtering of neurons and the differential placement of conductances on them. Model parameters (typically g(max) values) are therefore generally altered by hand or brute force to match model and neuron activity. We propose an alternative method in which complicated, rapidly changing driving input is used to optimize model parameters. This method also ensures that neuron and model dynamics match across a wide dynamic range, a test not performed in most modeling. We tested this concept using leech heartbeat and generic tonically firing models and lobster stomatogastric and generic bursting models as targets and g(max) values as optimized parameters. In all four cases optimization solutions excellently matched target activity. Complicated, wide dynamic range driving thus appears to be an excellent method to characterize neuron properties in detail and to build highly accurate models. In these completely defined targets, the method found each target's 8-13 g(max) values with high accuracy, and may therefore also provide an alternative, functionally based method of defining neuron g(max) values. The method uses only standard experimental and computational techniques, could be easily extended to optimize conductance parameters other than g(max), and should be readily applicable to real neurons.
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Affiliation(s)
- Kevin H Hobbs
- Department of Biological Sciences, Ohio University, Athens, OH 45701, USA
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26
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Navarro X, Vivó M, Valero-Cabré A. Neural plasticity after peripheral nerve injury and regeneration. Prog Neurobiol 2007; 82:163-201. [PMID: 17643733 DOI: 10.1016/j.pneurobio.2007.06.005] [Citation(s) in RCA: 619] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 02/18/2007] [Accepted: 06/14/2007] [Indexed: 01/01/2023]
Abstract
Injuries to the peripheral nerves result in partial or total loss of motor, sensory and autonomic functions conveyed by the lesioned nerves to the denervated segments of the body, due to the interruption of axons continuity, degeneration of nerve fibers distal to the lesion and eventual death of axotomized neurons. Injuries to the peripheral nervous system may thus result in considerable disability. After axotomy, neuronal phenotype switches from a transmitter to a regenerative state, inducing the down- and up-regulation of numerous cellular components as well as the synthesis de novo of some molecules normally not expressed in adult neurons. These changes in gene expression activate and regulate the pathways responsible for neuronal survival and axonal regeneration. Functional deficits caused by nerve injuries can be compensated by three neural mechanisms: the reinnervation of denervated targets by regeneration of injured axons, the reinnervation by collateral branching of undamaged axons, and the remodeling of nervous system circuitry related to the lost functions. Plasticity of central connections may compensate functionally for the lack of specificity in target reinnervation; plasticity in human has, however, limited effects on disturbed sensory localization or fine motor control after injuries, and may even result in maladaptive changes, such as neuropathic pain, hyperreflexia and dystonia. Recent research has uncovered that peripheral nerve injuries induce a concurrent cascade of events, at the systemic, cellular and molecular levels, initiated by the nerve injury and progressing throughout plastic changes at the spinal cord, brainstem relay nuclei, thalamus and brain cortex. Mechanisms for these changes are ubiquitous in central substrates and include neurochemical changes, functional alterations of excitatory and inhibitory connections, atrophy and degeneration of normal substrates, sprouting of new connections, and reorganization of somatosensory and motor maps. An important direction for ongoing research is the development of therapeutic strategies that enhance axonal regeneration, promote selective target reinnervation, but are also able to modulate central nervous system reorganization, amplifying those positive adaptive changes that help to improve functional recovery but also diminishing undesirable consequences.
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Affiliation(s)
- X Navarro
- Group of Neuroplasticity and Regeneration, Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain.
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27
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Chen X, Levine JD. Mechanically-evoked C-fiber activity in painful alcohol and AIDS therapy neuropathy in the rat. Mol Pain 2007; 3:5. [PMID: 17319957 PMCID: PMC1819368 DOI: 10.1186/1744-8069-3-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Accepted: 02/23/2007] [Indexed: 11/10/2022] Open
Abstract
While altered activities in sensory neurons were noticed in neuropathic pain, caused by highly diverse insults to the peripheral nervous system, such as diabetes, alcohol ingestion, cancer chemotherapy and drugs used to treat AIDS, other infections and autoimmune diseases, as well as trauma, our understanding of how these various peripheral neuropathies manifest as altered neuronal activity is still rudimentary. The recent development of models of several of those neuropathies has, however, now made it possible to address their impact on primary afferent nociceptor function. We compared changes in mechanically-evoked C-fiber activity, in models of painful peripheral neuropathy induced by drinking ethanol (alcohol) or administering 2',3'-dideoxycytidine (ddC), a nucleoside reverse transcriptase inhibitor for AIDS therapy, two co-morbid conditions in which pain is thought to be mediated by different second messenger signaling pathways. In C-fiber afferents, ddC decreased conduction velocity. In contrast, alcohol but not ddC caused enhanced response to mechanical stimulation (i.e., decrease in threshold and increase in response to sustained threshold and supra-threshold stimulation) and changes in pattern of evoked activity (interspike interval and action potential variability analyses). These marked differences in primary afferent nociceptor function, in two different forms of neuropathy that produce mechanical hyperalgesia of similar magnitude, suggest that optimal treatment of neuropathic pain may differ depending on the nature of the causative insult to the peripheral nervous system, and emphasize the value of studying co-morbid conditions that produce painful peripheral neuropathy by different mechanisms.
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Affiliation(s)
- Xiaojie Chen
- Departments of Anatomy, Medicine and Oral and Maxillofacial Surgery, Division of Neuroscience, NIH Pain Center, University of California, San Francisco, CA 94143, USA
| | - Jon D Levine
- Departments of Anatomy, Medicine and Oral and Maxillofacial Surgery, Division of Neuroscience, NIH Pain Center, University of California, San Francisco, CA 94143, USA
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28
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Rozen D, Grass GW. Intradiscal electrothermal coagulation and percutaneous neuromodulation therapy in the treatment of discogenic low back pain. Pain Pract 2006; 5:228-43. [PMID: 17147585 DOI: 10.1111/j.1533-2500.2005.05308.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Low back pain (LBP) is a major physical and socioeconomic entity. A significant percentage of LBP is attributable to internal disc disruption. The management of internal disc disruption has traditionally been limited to either conservative treatment or spinal fusion. Intradiscal electrothermal coagulation (IDET) and percutaneous neuromodulation therapy (PNT) are now being performed as an alternative to these therapies. Scientific data regarding the pathophysiology, biologic effects, and clinical results are relatively scarce. Early biomechanical and histologic investigations into the effects of IDET are conflicting. However, in early prospective human trials, IDET seems to provide some benefit with little risk. PNT represents a new less invasive technique for the treatment of discogenic pain, but limited research is available to determine long-term clinical efficacy. IDET and PNT are potentially beneficial treatments for internal disc disruption in carefully selected patients as an alternative to spinal fusion. More basic science and clinical research with long-term follow-up evaluation is necessary.
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Affiliation(s)
- Dima Rozen
- Department of Anesthesiology and Pain Medicine, Mount Sinai Medical Center, New York, New York 10029-6574, USA.
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29
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Abstract
The neurotrophin family of neurotrophic factors are well-known for their effects on neuronal survival and growth. Over the past decade, considerable evidence has accumulated from both humans and animals that one neurotrophin, nerve growth factor (NGF), is a peripheral pain mediator, particularly in inflammatory pain states. NGF is upregulated in a wide variety of inflammatory conditions, and NGF-neutralizing molecules are effective analgesic agents in many models of persistent pain. Such molecules are now being evaluated in clinical trials. NGF regulates the expression of a second neurotrophin, brain-derived neurotrophic factor (BDNF), in nociceptors. BDNF is released when nociceptors are activated, and it acts as a central modulator of pain. The chapter reviews the evidence for these roles (and briefly the effects of other neurotrophins), the range of conditions under which they act, and their mechanism of action.
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Affiliation(s)
- Sophie Pezet
- The London Pain Consortium, King's College London, The Wolfson Center for Age-Related Diseases, SE1 1UL London, United Kingdom.
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30
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Kow LM, Devidze N, Pataky S, Shibuya I, Pfaff DW. Acute estradiol application increases inward and decreases outward whole-cell currents of neurons in rat hypothalamic ventromedial nucleus. Brain Res 2006; 1116:1-11. [PMID: 16942760 DOI: 10.1016/j.brainres.2006.07.104] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Revised: 06/01/2006] [Accepted: 07/28/2006] [Indexed: 11/16/2022]
Abstract
Acute estradiol (E2) can potentiate the excitatory responses of hypothalamic ventromedial nucleus (VMN) neurons to neurotransmitters. To investigate the mechanism(s) underlying the potentiation, the whole-cell patch voltage clamp technique was used to study VMN neurons in hypothalamic slices prepared from female juvenile (3-5 weeks) rats. A voltage step and/or ramp was applied every 5 min to evoke whole-cell currents before, during and after a treatment with E2 (10 nM), corticosterone (10 nM) or vehicle for up to 20 min. Acute E2 increased inward currents in 38% of neurons tested. Their average peak inward current amplitudes started to increase within 5 min and reached the maximum of 163% of pretreatment level (Pre) at 20 min of treatment before recovering toward Pre. These increases are significantly greater than the Pre and corresponding vehicle controls and non-responsive neurons. Outward currents were decreased significantly by E2 in 27% of E2-treated cells, down to 60% of Pre levels. E2 also appeared to affect the kinetics of the inward and outward currents of estrogen-responsive neurons. Whenever observed, the effects of acute E2 were reversible after a 5- to 10-min washing. Probability analysis indicates that E2 affected the inward and the outward currents independently. The E2 effects are specific in that they were not produced by similar treatment with vehicle or corticosterone. Pharmacological characterizations using ion replacement and channel blockers showed that the inward currents were mediated practically all by Na(+) and the outward currents mainly by K(+). Thus, acute E2 can enhance inward Na(+) and attenuate outward K(+) currents. Since both effects will lead to an increase in neuronal excitability, they may explain our previous observation that E2 potentiates the excitation of VMN neurons.
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Affiliation(s)
- L-M Kow
- Laboratory of Neurobiology and Behavior, The Rockefeller University, 1230 York Avenue, Box 336, New York, NY 10021-6399, USA.
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31
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Haedo RJ, Golowasch J. Ionic mechanism underlying recovery of rhythmic activity in adult isolated neurons. J Neurophysiol 2006; 96:1860-76. [PMID: 16807346 PMCID: PMC3555141 DOI: 10.1152/jn.00385.2006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Neurons exhibit long-term excitability changes necessary for maintaining proper cell and network activity in response to various inputs and perturbations. For instance, the adult crustacean pyloric network can spontaneously recover rhythmic activity after complete shutdown resulting from permanent removal of neuromodulatory inputs. Dissociated lobster stomatogastric ganglion (STG) neurons have been shown to spontaneously develop oscillatory activity via excitability changes. Rhythmic electrical stimulation can eliminate these oscillatory patterns in some cells. The ionic mechanisms underlying these changes are only partially understood. We used dissociated crab STG neurons to study the ionic mechanisms underlying spontaneous recovery of rhythmic activity and stimulation-induced activity changes. Similar to lobster neurons, rhythmic activity spontaneously develops in crab STG neurons. Rhythmic hyperpolarizing stimulation can eliminate, but more commonly accelerate, the emergence of stable oscillatory activity depending on Ca(2+) influx at hyperpolarized voltages. Our main finding is that upregulation of a Ca(2+) current and downregulation of a high-threshold K(+) current underlies the spontaneous homeostatic development of oscillatory activity. However, because of a nonlinear dependence on stimulus frequency, hyperpolarization-induced oscillations appear to be inconsistent with a homeostatic regulation of activity. We find no difference in the activity patterns or the underlying ionic currents involved between neurons of the fast pyloric and the slow gastric mill networks during the first 10 days in isolation. Dynamic-clamp experiments confirm that these conductance modifications can explain the observed activity changes. We conclude that spontaneous and stimulation-induced excitability changes in STG neurons can both result in intrinsic oscillatory activity via regulation of the same two conductances.
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Affiliation(s)
- Rodolfo J. Haedo
- Department of Biological Sciences, Rutgers University, Newark, NJ 07102
| | - Jorge Golowasch
- Department of Biological Sciences, Rutgers University, Newark, NJ 07102
- Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, NJ 07102
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32
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Abstract
The induction of action potentials in airway sensory nerves relies on events leading to the opening of cation channels in the nerve terminal membrane and subsequent membrane depolarization. If the membrane depolarization is of sufficient rate and amplitude, action potential initiation will occur. The action potentials are then conducted to the central nervous system, leading to the initiation of various sensations and cardiorespiratory reflexes. Triggering events in airway sensory nerves include mechanical perturbation, inflammatory mediators, pH, temperature, and osmolarity acting through a variety of ionotropic and metabotropic receptors. Action potential initiation can be modulated (positively or negatively) through independent mechanisms caused mainly by autacoids and other metabotropic receptor ligands. Finally, gene expression of sensory nerves can be altered in adult mammals. This neuroplasticity can change the function of sensory nerves and likely involve both neurotrophin and use-dependent mechanisms. Here we provide a brief overview of some of the transduction mechanisms underlying these events.
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33
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Brackenbury WJ, Djamgoz MBA. Activity-dependent regulation of voltage-gated Na+ channel expression in Mat-LyLu rat prostate cancer cell line. J Physiol 2006; 573:343-56. [PMID: 16543264 PMCID: PMC1779734 DOI: 10.1113/jphysiol.2006.106906] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
We have shown previously that voltage-gated Na(+) channels (VGSCs) are up-regulated in human metastatic disease (prostate, breast and small-cell lung cancers), and that VGSC activity potentiates metastatic cell behaviours. However, the mechanism(s) regulating functional VGSC expression in cancer cells remains unknown. We investigated the possibility of activity-dependent (auto)regulation of VGSC functional expression in the strongly metastatic Mat-LyLu model of rat prostate cancer. Pretreatment with tetrodotoxin (TTX) for 24-72 h subsequently suppressed peak VGSC current density without affecting voltage dependence. The hypothesis was tested that the VGSC auto-regulation occurred via VGSC-mediated Na(+) influx and subsequent activation of protein kinase A (PKA). Indeed, TTX pretreatment reduced the level of phosphorylated PKA, and the PKA inhibitor KT5720 decreased, whilst the adenylate cyclase activator forskolin and the Na(+) ionophore monensin both increased the peak VGSC current density. TTX reduced the mRNA level of Nav1.7, predominant in these cells, and VGSC protein expression at the plasma membrane, although the total VGSC protein level remained unchanged. TTX pretreatment eliminated the VGSC-dependent component of the cells' migration in Transwell assays. We concluded that the VGSC activity in Mat-LyLu rat prostate cancer cells was up-regulated in steady-state via a positive feedback mechanism involving PKA, and this enhanced the cells' migratory potential.
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Affiliation(s)
- William J Brackenbury
- Neuroscience Solutions to Cancer Research Group, Division of Cell and Molecular Biology, Sir Alexander Fleming Building, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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34
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Waxman SG, Hains BC. Fire and phantoms after spinal cord injury: Na+ channels and central pain. Trends Neurosci 2006; 29:207-15. [PMID: 16494954 DOI: 10.1016/j.tins.2006.02.003] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2005] [Revised: 01/10/2006] [Accepted: 02/09/2006] [Indexed: 10/25/2022]
Abstract
Neuropathic pain and phantom phenomena occur commonly after spinal cord injury (SCI) but their molecular basis is not yet fully understood. Recent findings demonstrate abnormal expression of the Nav1.3 Na(+) channel within second-order spinal cord dorsal horn neurons and third-order thalamic neurons along the pain pathway after SCI, and suggest that this change makes these neurons hyperexcitable so that they act as pain amplifiers and generators. Delineation of molecular changes that contribute to hyperexcitability of pain-signaling neurons might lead to identification of molecular targets that will be useful in the treatment of neuropathic pain after SCI and related nervous system injuries.
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Affiliation(s)
- Stephen G Waxman
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.
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35
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Fields RD, Lee PR, Cohen JE. Temporal integration of intracellular Ca2+ signaling networks in regulating gene expression by action potentials. Cell Calcium 2005; 37:433-42. [PMID: 15820391 DOI: 10.1016/j.ceca.2005.01.011] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2004] [Accepted: 01/06/2005] [Indexed: 01/05/2023]
Abstract
Temporal aspects of intracellular calcium signaling are particularly important in activity-dependent regulation of gene expression in neurons. This review traces calcium-dependent intracellular signaling from the membrane to the nucleus in response to action-potential firing, and considers how specific genes are regulated by specific patterns of impulse firing. Modes of calcium influx, calcium-dependent protein kinases, transcription factors, individual genes, and genomic analysis are examined, with particular emphasis on the importance of temporal aspects of calcium dynamics in regulating these processes.
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Affiliation(s)
- R Douglas Fields
- Nervous System Development and Plasticity Section, National Institutes of Health, NICHD, Bldg. 35, Room 2A211, MSC 3713, 35 Lincoln Drive, Bethesda, MD 20892, USA.
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36
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Moody WJ, Bosma MM. Ion Channel Development, Spontaneous Activity, and Activity-Dependent Development in Nerve and Muscle Cells. Physiol Rev 2005; 85:883-941. [PMID: 15987798 DOI: 10.1152/physrev.00017.2004] [Citation(s) in RCA: 281] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
At specific stages of development, nerve and muscle cells generate spontaneous electrical activity that is required for normal maturation of intrinsic excitability and synaptic connectivity. The patterns of this spontaneous activity are not simply immature versions of the mature activity, but rather are highly specialized to initiate and control many aspects of neuronal development. The configuration of voltage- and ligand-gated ion channels that are expressed early in development regulate the timing and waveform of this activity. They also regulate Ca2+influx during spontaneous activity, which is the first step in triggering activity-dependent developmental programs. For these reasons, the properties of voltage- and ligand-gated ion channels expressed by developing neurons and muscle cells often differ markedly from those of adult cells. When viewed from this perspective, the reasons for complex patterns of ion channel emergence and regression during development become much clearer.
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Affiliation(s)
- William J Moody
- Department of Biology, University of Washington, Seattle, Washington 98195, USA.
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Waxman SG. Cerebellar dysfunction in multiple sclerosis: evidence for an acquired channelopathy. PROGRESS IN BRAIN RESEARCH 2005; 148:353-65. [PMID: 15661203 DOI: 10.1016/s0079-6123(04)48028-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Cerebellar dysfunction in multiple sclerosis (MS) is a significant contributor to disability, is relatively refractory to symptomatic therapy, and often progresses despite treatment with disease-modifying agents. Thus, there is a need for better understanding of its pathophysiology. This chapter reviews a growing body of evidence which suggests that mis-tuning of Purkinje cells, due to expression of an abnormal repertoire of sodium channels, contributes to cerebellar deficits in MS. Within the normal nervous system, sodium channel Na(v)1.8 is expressed in a highly specific manner within spinal sensory and trigeminal neurons, and is not present within Purkinje cells, Na(v)1.8 mRNA and protein are, however, expressed within Purkinje cells both in models of MS (experimenal autoimmume encephalomyelitis; EAE), and in postmortem tissue from humans with MS. Expression of Na(v)1.8 within Purkinje cells in vitro alters electrogenesis in these cells in several ways: first, by increasing duration and amplitude of action potentials; second, by decreasing the proportion of action potentials that are conglomerate and the number of spikes per conglomerate action potential; and third, by supporting sustained, pacemaker-like impulse trains in response to depolarization, which are not seen in the absence of Na(v)1.8. Similar changes are observed in recordings from Purkinje cells in vivo from mice with EAE. Taken together, these results suggest that expression of Na(v)1.8 within Purkinje cells distorts their pattern of firing in MS.
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Affiliation(s)
- Stephen G Waxman
- Department of Neurology and PVA/EPVA Center for Neuroscience Research, Yale University School of Medicine, New Haven, CT 06510 and Rehabilitation Research Center, VA Hospital, West Haven, CT 06516, USA
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Tsuboi Y, Takeda M, Tanimoto T, Ikeda M, Matsumoto S, Kitagawa J, Teramoto K, Simizu K, Yamazaki Y, Shima A, Ren K, Iwata K. Alteration of the second branch of the trigeminal nerve activity following inferior alveolar nerve transection in rats. Pain 2004; 111:323-334. [PMID: 15363876 DOI: 10.1016/j.pain.2004.07.014] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2004] [Revised: 05/31/2004] [Accepted: 07/12/2004] [Indexed: 12/31/2022]
Abstract
After transection of the inferior alveolar nerve (IAN), the whisker pad area, which is innervated by the infraorbital nerve (ION) that was not injured, showed hypersensitivity to mechanical stimulation. Two days after IAN transection, threshold intensity for escape behavior to mechanical stimulation of the ipsilateral whisker pad area was less than 4.0 g, indicating mechanical allodynia. A total of 68 single fiber discharges were recorded from ION fibers at 3 days after IAN transection. The responses of C- and A-fibers were classified according to their conduction velocity. The C-fiber activities were not affected by IAN transection, whereas A-fiber activities were significantly enhanced by IAN transection as indicated by an increase in background activity and mechanically evoked response. Since the A-fiber responses were significantly affected by IAN transection, patch clamp recording was performed from middle to large diameter retrogradely labeled and acutely dissociated trigeminal ganglion (TRG) neurons. The I(K) (sustained) and I(A) (transient) currents were significantly smaller and hyperpolarization-activated current (I(h)) was significantly larger in TRG neurons of rats with IAN transection as compared to those of naive rats. Furthermore, current injection into TRG neurons induced high frequency spike discharges in rats with IAN transection. These data suggest that changes in K(+) current and I(h) observed in the uninjured TRG neurons reflect an increase in excitability of TRG neurons innervated by the ION after IAN transection, resulting in the development of mechano-allodynia in the area adjacent to the injured IAN innervated region.
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Affiliation(s)
- Yoshiyuki Tsuboi
- Department of Physiology, School of Dentistry, Nihon University, Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan Department of Physiology, School of Dentistry at Tokyo, Nippon Dental University, 1-9-20, Fujimi-cho, Chiyoda-ku, Tokyo 102-8159, Japan Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo 101-8310, Japan Department of Dysphagia Rehabilitation, Nihon University School of Dentistry, Tokyo 101-8310, Japan Department of Dental Anesthesiology, Nihon University School of Dentistry, Tokyo 101-8310, Japan Department of Biomedical Sciences, University of Maryland Dental School, Baltimore, MD 21201, USA Division of Applied System Neuroscience Advanced Medical Research Center, Nihon University Graduate School of Medical Science, 30-1 Ohyaguchi-Kamimachi Itabashi, Tokyo 173-8610, Japan
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