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Qualls KA, Xie W, Zhang J, Lückemeyer DD, Lackey SV, Strong JA, Zhang JM. Mineralocorticoid Receptor Antagonism Reduces Inflammatory Pain Measures in Mice Independent of the Receptors on Sensory Neurons. Neuroscience 2024; 541:64-76. [PMID: 38307407 DOI: 10.1016/j.neuroscience.2024.01.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 02/04/2024]
Abstract
Corticosteroids are commonly used in the treatment of inflammatory low back pain, and their nominal target is the glucocorticoid receptor (GR) to relieve inflammation. They can also have similar potency at the mineralocorticoid receptor (MR). The MR has been shown to be widespread in rodent and human dorsal root ganglia (DRG) neurons and non-neuronal cells, and when MR antagonists are administered during a variety of inflammatory pain models in rats, pain measures are reduced. In this study we selectively knockout (KO) the MR in sensory neurons to determine the role of MR in sensory neurons of the mouse DRG in pain measures as MR antagonism during the local inflammation of the DRG (LID) pain model. We found that MR antagonism using eplerenone reduced evoked mechanical hypersensitivity during LID, but MR KO in paw-innervating sensory neurons only did not. This could be a result of differences between prolonged (MR KO) versus acute (drug) MR block or an indicator that non-neuronal cells in the DRG are driving the effect of MR antagonists. MR KO unmyelinated C neurons are more excitable under normal and inflamed conditions, while MR KO does not affect excitability of myelinated A cells. MR KO in sensory neurons causes a reduction in overall GR mRNA but is protective against reduction of the anti-inflammatory GRα isoform during LID. These effects of MR KO in sensory neurons expanded our understanding of MR's functional role in different neuronal subtypes (A and C neurons), and its interactions with the GR.
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Affiliation(s)
- Katherine A Qualls
- Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Wenrui Xie
- Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Jietong Zhang
- Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Debora Denardin Lückemeyer
- Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Sierra V Lackey
- Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Judith A Strong
- Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Jun-Ming Zhang
- Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
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2
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Sas D, Gaudel F, Verdier D, Kolta A. Hyperexcitability of muscle spindle afferents in jaw-closing muscles in experimental myalgia: Evidence for large primary afferents involvement in chronic pain. Exp Physiol 2024; 109:100-111. [PMID: 38103003 PMCID: PMC10988680 DOI: 10.1113/ep090769] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Accepted: 11/30/2023] [Indexed: 12/17/2023]
Abstract
The goals of this review are to improve understanding of the aetiology of chronic muscle pain and identify new targets for treatments. Muscle pain is usually associated with trigger points in syndromes such as fibromyalgia and myofascial syndrome, and with small spots associated with spontaneous electrical activity that seems to emanate from fibers inside muscle spindles in EMG studies. These observations, added to the reports that large-diameter primary afferents, such as those innervating muscle spindles, become hyperexcitable and develop spontaneous ectopic firing in conditions leading to neuropathic pain, suggest that changes in excitability of these afferents might make an important contribution to the development of pathological pain. Here, we review evidence that the muscle spindle afferents (MSAs) of the jaw-closing muscles become hyperexcitable in a model of chronic orofacial myalgia. In these afferents, as in other large-diameter primary afferents in dorsal root ganglia, firing emerges from fast membrane potential oscillations that are supported by a persistent sodium current (INaP ) mediated by Na+ channels containing the α-subunit NaV 1.6. The current flowing through NaV 1.6 channels increases when the extracellular Ca2+ concentration decreases, and studies have shown that INaP -driven firing is increased by S100β, an astrocytic protein that chelates Ca2+ when released in the extracellular space. We review evidence of how astrocytes, which are known to be activated in pain conditions, might, through their regulation of extracellular Ca2+ , contribute to the generation of ectopic firing in MSAs. To explain how ectopic firing in MSAs might cause pain, we review evidence supporting the hypothesis that cross-talk between proprioceptive and nociceptive pathways might occur in the periphery, within the spindle capsule.
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Affiliation(s)
- Dar'ya Sas
- Département de NeurosciencesUniversité de MontréalMontréalQuébecCanada
- Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA)MontréalQuébecCanada
| | - Fanny Gaudel
- Département de NeurosciencesUniversité de MontréalMontréalQuébecCanada
- Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA)MontréalQuébecCanada
| | - Dorly Verdier
- Département de NeurosciencesUniversité de MontréalMontréalQuébecCanada
- Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA)MontréalQuébecCanada
| | - Arlette Kolta
- Département de NeurosciencesUniversité de MontréalMontréalQuébecCanada
- Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA)MontréalQuébecCanada
- Faculté de Médecine DentaireUniversité de MontréalMontréalQuébecCanada
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Maksymchuk N, Sakurai A, Cox DN, Cymbalyuk GS. Cold-Temperature Coding with Bursting and Spiking Based on TRP Channel Dynamics in Drosophila Larva Sensory Neurons. Int J Mol Sci 2023; 24:14638. [PMID: 37834085 PMCID: PMC10572325 DOI: 10.3390/ijms241914638] [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: 06/06/2023] [Revised: 08/30/2023] [Accepted: 09/05/2023] [Indexed: 10/15/2023] Open
Abstract
Temperature sensation involves thermosensitive TRP (thermoTRP) and non-TRP channels. Drosophila larval Class III (CIII) neurons serve as the primary cold nociceptors and express a suite of thermoTRP channels implicated in noxious cold sensation. How CIII neurons code temperature remains unclear. We combined computational and electrophysiological methods to address this question. In electrophysiological experiments, we identified two basic cold-evoked patterns of CIII neurons: bursting and spiking. In response to a fast temperature drop to noxious cold, CIII neurons distinctly mark different phases of the stimulus. Bursts frequently occurred along with the fast temperature drop, forming a peak in the spiking rate and likely coding the high rate of the temperature change. Single spikes dominated at a steady temperature and exhibited frequency adaptation following the peak. When temperature decreased slowly to the same value, mainly spiking activity was observed, with bursts occurring sporadically throughout the stimulation. The spike and the burst frequencies positively correlated with the rate of the temperature drop. Using a computational model, we explain the distinction in the occurrence of the two CIII cold-evoked patterns bursting and spiking using the dynamics of a thermoTRP current. A two-parameter activity map (Temperature, constant TRP current conductance) marks parameters that support silent, spiking, and bursting regimes. Projecting on the map the instantaneous TRP conductance, governed by activation and inactivation processes, reflects temperature coding responses as a path across silent, spiking, or bursting domains on the map. The map sheds light on how various parameter sets for TRP kinetics represent various types of cold-evoked responses. Together, our results indicate that bursting detects the high rate of temperature change, whereas tonic spiking could reflect both the rate of change and magnitude of steady cold temperature.
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Affiliation(s)
- Natalia Maksymchuk
- Neuroscience Institute, Georgia State University, Atlanta, GA 30302-5030, USA; (N.M.); (A.S.); (D.N.C.)
| | - Akira Sakurai
- Neuroscience Institute, Georgia State University, Atlanta, GA 30302-5030, USA; (N.M.); (A.S.); (D.N.C.)
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA 30302-5030, USA; (N.M.); (A.S.); (D.N.C.)
| | - Gennady S. Cymbalyuk
- Neuroscience Institute, Georgia State University, Atlanta, GA 30302-5030, USA; (N.M.); (A.S.); (D.N.C.)
- Department of Biology, Georgia State University, Atlanta, GA 30302-5030, USA
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Berta T, Strong JA, Zhang JM, Ji RR. Targeting dorsal root ganglia and primary sensory neurons for the treatment of chronic pain: an update. Expert Opin Ther Targets 2023; 27:665-678. [PMID: 37574713 PMCID: PMC10530032 DOI: 10.1080/14728222.2023.2247563] [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: 04/04/2023] [Revised: 06/30/2023] [Accepted: 08/09/2023] [Indexed: 08/15/2023]
Abstract
INTRODUCTION Current treatments for chronic pain are inadequate. Here, we provide an update on the new therapeutic strategies that target dorsal root ganglia (DRGs) in the peripheral nervous system for a better and safer treatment of chronic pain. AREAS COVERED Despite the complex nature of chronic pain and its underlying mechanisms, we do know that changes in the plasticity and modality of neurons in DRGs play a pivotal role. DRG neurons are heterogenous and offer potential pain targets for different therapeutic interventions. We discuss the last advancements of these interventions, which include the use of systemic and local administrations, selective nerve drug delivery, and gene therapy. In particular, we provide updates and further details on the molecular characterization of primary sensory neurons, new analgesics entering the market, and future gene therapy approaches. EXPERT OPINION DRGs and primary sensory neurons are promising targets for chronic pain treatment due to their key role in pain signaling, unique anatomical location, and the potential for different targeted therapeutic interventions.
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Affiliation(s)
- Temugin Berta
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA
| | - Judith A. Strong
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA
| | - Jun-Ming Zhang
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA
| | - Ru-Rong Ji
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
- Departments of Cell Biology and Neurobiology, Duke University Medical Center, Durham, North Carolina 27710
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Vieira AR, Sekula RF, Deeley K. Classical trigeminal neuralgia is associated with gephyrin and sodium voltage-gated channel alpha subunit 8. FRONTIERS IN DENTAL MEDICINE 2023. [DOI: 10.3389/fdmed.2022.988094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Trigeminal neuralgia is highly debilitating, and its etiology is still undefined. The goal of this work was to define associations between well-characterized trigeminal neuralgia cases and common genetic variants in the population. two hundred and fifty-seven individuals diagnosed with classical trigeminal neuralgia were compared to 865 individuals without classical trigeminal neuralgia and with an assessment for lower or higher pain threshold based on the amount of anesthetic required for routine dental treatment. Genotypes of 24 variants marking genes in the VGSC (voltage-gated sodium channels) or GABA (gamma-aminobutyric acid) pathways were obtained using TaqMan chemistry end end-point analysis. Chi-square was used for all comparisons with an alpha of 0.002. An association between classical trigeminal neuralgia and individuals requiring less or more anesthetic for routine dental treatments showed associations with SCN8A rs1601012 and GPHN rs723432 (p = 0.0009 and p = 0.0002, respectively). In conclusion, classical trigeminal neuralgia is associated with SCN8A and GPHN and markers rs1601012 rs723432 may be useful to determine individual risks for the condition.
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Klein RM, Layton ME, Regan H, Regan CP, Li Y, Filzen T, Cato M, Clements MK, Wang J, Sanoja R, Greshock TJ, Roecker AJ, Pero JE, Kim R, Burgey C, John CT, Wang YH, Bhandari N, Struyk A, Kraus RL, Henze DA, Houghton AK. Association of respiratory failure with inhibition of NaV1.6 in the phrenic nerve. Channels (Austin) 2022; 16:230-243. [PMID: 36239534 PMCID: PMC9578445 DOI: 10.1080/19336950.2022.2122309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
As part of a drug discovery effort to identify potent inhibitors of NaV1.7 for the treatment of pain, we observed that inhibitors produced unexpected cardiovascular and respiratory effects in vivo. Specifically, inhibitors administered to rodents produced changes in cardiovascular parameters and respiratory cessation. We sought to determine the mechanism of the in vivo adverse effects by studying the selectivity of the compounds on NaV1.5, NaV1.4, and NaV1.6 in in vitro and ex vivo assays. Inhibitors lacking sufficient NaV1.7 selectivity over NaV1.6 were associated with respiratory cessation after in vivo administration to rodents. Effects on respiratory rate in rats were consistent with effects in an ex vivo hemisected rat diaphragm model and in vitro NaV1.6 potency. Furthermore, direct blockade of the phrenic nerve signaling was observed at exposures known to cause respiratory cessation in rats. Collectively, these results support a significant role for NaV1.6 in phrenic nerve signaling and respiratory function.
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Affiliation(s)
- Rebecca M. Klein
- Merck Research Laboratories, Merck & Co., Rahway, NJ, USA,CONTACT Rebecca M. Klein 770 Sumneytown Pike, P.O. Box 4, West Point, PA19486, USA
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Elleman AV, Du Bois J. Chemical and Biological Tools for the Study of Voltage-Gated Sodium Channels in Electrogenesis and Nociception. Chembiochem 2022; 23:e202100625. [PMID: 35315190 PMCID: PMC9359671 DOI: 10.1002/cbic.202100625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/22/2022] [Indexed: 12/17/2022]
Abstract
The malfunction and misregulation of voltage-gated sodium channels (NaV s) underlie in large part the electrical hyperexcitability characteristic of chronic inflammatory and neuropathic pain. NaV s are responsible for the initiation and propagation of electrical impulses (action potentials) in cells. Tissue and nerve injury alter the expression and localization of multiple NaV isoforms, including NaV 1.1, 1.3, and 1.6-1.9, resulting in aberrant action potential firing patterns. To better understand the role of NaV regulation, localization, and trafficking in electrogenesis and pain pathogenesis, a number of chemical and biological reagents for interrogating NaV function have been advanced. The development and application of such tools for understanding NaV physiology are the focus of this review.
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Affiliation(s)
- Anna V Elleman
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - J Du Bois
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
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Neuroimmune Mechanisms Underlying Neuropathic Pain: The Potential Role of TNF-α-Necroptosis Pathway. Int J Mol Sci 2022; 23:ijms23137191. [PMID: 35806192 PMCID: PMC9266916 DOI: 10.3390/ijms23137191] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/24/2022] [Accepted: 06/27/2022] [Indexed: 02/05/2023] Open
Abstract
The neuroimmune mechanism underlying neuropathic pain has been extensively studied. Tumor necrosis factor-alpha (TNF-α), a key pro-inflammatory cytokine that drives cytokine storm and stimulates a cascade of other cytokines in pain-related pathways, induces and modulates neuropathic pain by facilitating peripheral (primary afferents) and central (spinal cord) sensitization. Functionally, TNF-α controls the balance between cell survival and death by inducing an inflammatory response and two programmed cell death mechanisms (apoptosis and necroptosis). Necroptosis, a novel form of programmed cell death, is receiving increasing attraction and may trigger neuroinflammation to promote neuropathic pain. Chronic pain is often accompanied by adverse pain-associated emotional reactions and cognitive disorders. Overproduction of TNF-α in supraspinal structures such as the anterior cingulate cortex (ACC) and hippocampus plays an important role in pain-associated emotional disorders and memory deficits and also participates in the modulation of pain transduction. At present, studies reporting on the role of the TNF-α–necroptosis pathway in pain-related disorders are lacking. This review indicates the important research prospects of this pathway in pain modulation based on its role in anxiety, depression and memory deficits associated with other neurodegenerative diseases. In addition, we have summarized studies related to the underlying mechanisms of neuropathic pain mediated by TNF-α and discussed the role of the TNF-α–necroptosis pathway in detail, which may represent an avenue for future therapeutic intervention.
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Li QY, Chen SX, Liu JY, Yao PW, Duan YW, Li YY, Zang Y. Neuroinflammation in the anterior cingulate cortex: the potential supraspinal mechanism underlying the mirror-image pain following motor fiber injury. J Neuroinflammation 2022; 19:162. [PMID: 35725625 PMCID: PMC9210588 DOI: 10.1186/s12974-022-02525-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 06/06/2022] [Indexed: 11/10/2022] Open
Abstract
Background Peripheral nerve inflammation or lesion can affect contralateral healthy structures, and thus result in mirror-image pain. Supraspinal structures play important roles in the occurrence of mirror pain. The anterior cingulate cortex (ACC) is a first-order cortical region that responds to painful stimuli. In the present study, we systematically investigate and compare the neuroimmune changes in the bilateral ACC region using unilateral- (spared nerve injury, SNI) and mirror-(L5 ventral root transection, L5-VRT) pain models, aiming to explore the potential supraspinal neuroimmune mechanism underlying the mirror-image pain. Methods The up-and-down method with von Frey hairs was used to measure the mechanical allodynia. Viral injections for the designer receptors exclusively activated by designer drugs (DREADD) were used to modulate ACC glutamatergic neurons. Immunohistochemistry, immunofluorescence, western blotting, protein microarray were used to detect the regulation of inflammatory signaling. Results Increased expressions of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and chemokine CX3CL1 in ACC induced by unilateral nerve injury were observed on the contralateral side in the SNI group but on the bilateral side in the L5-VRT group, representing a stronger immune response to L5-VRT surgery. In remote ACC, both SNI and L5-VRT induced robust bilateral increase in the protein level of Nav1.6 (SCN8A), a major voltage-gated sodium channel (VGSC) that regulates neuronal activity in the mammalian nervous system. However, the L5-VRT-induced Nav1.6 response occurred at PO 3d, earlier than the SNI-induced one, 7 days after surgery. Modulating ACC glutamatergic neurons via DREADD-Gq or DREADD-Gi greatly changed the ACC CX3CL1 levels and the mechanical paw withdrawal threshold. Neutralization of endogenous ACC CX3CL1 by contralateral anti-CX3CL1 antibody attenuated the induction and the maintenance of mechanical allodynia and eliminated the upregulation of CX3CL1, TNF-α and Nav1.6 protein levels in ACC induced by SNI. Furthermore, contralateral ACC anti-CX3CL1 also inhibited the expression of ipsilateral spinal c-Fos, Iba1, CD11b, TNF-α and IL-6. Conclusions The descending facilitation function mediated by CX3CL1 and its downstream cascade may play a pivotal role, leading to enhanced pain sensitization and even mirror-image pain. Strategies that target chemokine-mediated ACC hyperexcitability may lead to novel therapies for the treatment of neuropathic pain. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-022-02525-8.
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Affiliation(s)
- Qiao-Yun Li
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China
| | - Shao-Xia Chen
- Department of Anesthesiology, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, 651 Dongfeng Road East, Guangzhou, 510060, People's Republic of China
| | - Jin-Yu Liu
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China
| | - Pei-Wen Yao
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China
| | - Yi-Wen Duan
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China
| | - Yong-Yong Li
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China
| | - Ying Zang
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China.
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10
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Alles SRA, Smith PA. Peripheral Voltage-Gated Cation Channels in Neuropathic Pain and Their Potential as Therapeutic Targets. FRONTIERS IN PAIN RESEARCH 2021; 2:750583. [PMID: 35295464 PMCID: PMC8915663 DOI: 10.3389/fpain.2021.750583] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 11/10/2021] [Indexed: 11/25/2022] Open
Abstract
The persistence of increased excitability and spontaneous activity in injured peripheral neurons is imperative for the development and persistence of many forms of neuropathic pain. This aberrant activity involves increased activity and/or expression of voltage-gated Na+ and Ca2+ channels and hyperpolarization activated cyclic nucleotide gated (HCN) channels as well as decreased function of K+ channels. Because they display limited central side effects, peripherally restricted Na+ and Ca2+ channel blockers and K+ channel activators offer potential therapeutic approaches to pain management. This review outlines the current status and future therapeutic promise of peripherally acting channel modulators. Selective blockers of Nav1.3, Nav1.7, Nav1.8, Cav3.2, and HCN2 and activators of Kv7.2 abrogate signs of neuropathic pain in animal models. Unfortunately, their performance in the clinic has been disappointing; some substances fail to meet therapeutic end points whereas others produce dose-limiting side effects. Despite this, peripheral voltage-gated cation channels retain their promise as therapeutic targets. The way forward may include (i) further structural refinement of K+ channel activators such as retigabine and ASP0819 to improve selectivity and limit toxicity; use or modification of Na+ channel blockers such as vixotrigine, PF-05089771, A803467, PF-01247324, VX-150 or arachnid toxins such as Tap1a; the use of Ca2+ channel blockers such as TTA-P2, TTA-A2, Z 944, ACT709478, and CNCB-2; (ii) improving methods for assessing "pain" as opposed to nociception in rodent models; (iii) recognizing sex differences in pain etiology; (iv) tailoring of therapeutic approaches to meet the symptoms and etiology of pain in individual patients via quantitative sensory testing and other personalized medicine approaches; (v) targeting genetic and biochemical mechanisms controlling channel expression using anti-NGF antibodies such as tanezumab or re-purposed drugs such as vorinostat, a histone methyltransferase inhibitor used in the management of T-cell lymphoma, or cercosporamide a MNK 1/2 inhibitor used in treatment of rheumatoid arthritis; (vi) combination therapy using drugs that are selective for different channel types or regulatory processes; (vii) directing preclinical validation work toward the use of human or human-derived tissue samples; and (viii) application of molecular biological approaches such as clustered regularly interspaced short palindromic repeats (CRISPR) technology.
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Affiliation(s)
- Sascha R A Alles
- Department of Anesthesiology and Critical Care Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Peter A Smith
- Department of Pharmacology, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
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11
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Abstract
Neuropathic pain (NP) is a common symptom in many diseases of the somatosensory
nervous system, which severely affects the patient’s quality of life.
Epigenetics are heritable alterations in gene expression that do not cause
permanent changes in the DNA sequence. Epigenetic modifications can affect gene
expression and function and can also mediate crosstalk between genes and the
environment. Increasing evidence shows that epigenetic modifications, including
DNA methylation, histone modification, non-coding RNA, and RNA modification, are
involved in the development and maintenance of NP. In this review, we focus on
the current knowledge of epigenetic modifications in the development and
maintenance of NP. Then, we illustrate different facets of epigenetic
modifications that regulate gene expression and their crosstalk. Finally, we
discuss the burgeoning evidence supporting the potential of emerging epigenetic
therapies, which has been valuable in understanding mechanisms and offers novel
and potent targets for NP therapy.
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Affiliation(s)
- Danzhi Luo
- Department of Anesthesiology, The First People’s Hospital of
Foshan, Foshan, China
- Sun Yet-Sen Memorial Hospital of Sun
Yet-Sen University, Guangzhou, China
| | - Xiaohong Li
- Department of Anesthesiology, The First People’s Hospital of
Foshan, Foshan, China
| | - Simin Tang
- Department of Anesthesiology, The Third Affiliated Hospital of
Southern Medical University, Guangzhou, China
| | - Fuhu Song
- Department of Anesthesiology, The Third Affiliated Hospital of
Southern Medical University, Guangzhou, China
| | - Wenjun Li
- Department of Anesthesiology, The Third Affiliated Hospital of
Southern Medical University, Guangzhou, China
| | - Guiling Xie
- Department of Anesthesiology, The Third Affiliated Hospital of
Southern Medical University, Guangzhou, China
| | - Jinshu Liang
- Department of Anesthesiology, The Third Affiliated Hospital of
Southern Medical University, Guangzhou, China
| | - Jun Zhou
- Department of Anesthesiology, The Third Affiliated Hospital of
Southern Medical University, Guangzhou, China
- Jun Zhou, Department of Anesthesiology, The
Third Affiliated Hospital of Southern Medical University, Guangzhou 510630,
China.
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12
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Zybura A, Hudmon A, Cummins TR. Distinctive Properties and Powerful Neuromodulation of Na v1.6 Sodium Channels Regulates Neuronal Excitability. Cells 2021; 10:cells10071595. [PMID: 34202119 PMCID: PMC8307729 DOI: 10.3390/cells10071595] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 06/20/2021] [Accepted: 06/21/2021] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (Navs) are critical determinants of cellular excitability. These ion channels exist as large heteromultimeric structures and their activity is tightly controlled. In neurons, the isoform Nav1.6 is highly enriched at the axon initial segment and nodes, making it critical for the initiation and propagation of neuronal impulses. Changes in Nav1.6 expression and function profoundly impact the input-output properties of neurons in normal and pathological conditions. While mutations in Nav1.6 may cause channel dysfunction, aberrant changes may also be the result of complex modes of regulation, including various protein-protein interactions and post-translational modifications, which can alter membrane excitability and neuronal firing properties. Despite decades of research, the complexities of Nav1.6 modulation in health and disease are still being determined. While some modulatory mechanisms have similar effects on other Nav isoforms, others are isoform-specific. Additionally, considerable progress has been made toward understanding how individual protein interactions and/or modifications affect Nav1.6 function. However, there is still more to be learned about how these different modes of modulation interact. Here, we examine the role of Nav1.6 in neuronal function and provide a thorough review of this channel’s complex regulatory mechanisms and how they may contribute to neuromodulation.
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Affiliation(s)
- Agnes Zybura
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
- Biology Department, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Andy Hudmon
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA;
| | - Theodore R. Cummins
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
- Biology Department, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
- Correspondence:
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13
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Geisler S. Vincristine- and bortezomib-induced neuropathies - from bedside to bench and back. Exp Neurol 2021; 336:113519. [PMID: 33129841 PMCID: PMC11160556 DOI: 10.1016/j.expneurol.2020.113519] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 10/21/2020] [Accepted: 10/25/2020] [Indexed: 12/11/2022]
Abstract
Vincristine and bortezomib are effective chemotherapeutics widely used to treat hematological cancers. Vincristine blocks tubulin polymerization, whereas bortezomib is a proteasome inhibitor. Despite different mechanisms of action, the main non-hematological side effect of both is peripheral neuropathy that can last long after treatment has ended and cause permanent disability. Many different cellular and animal models of various aspects of vincristine and bortezomib-induced neuropathies have been generated to investigate underlying molecular mechanisms and serve as platforms to develop new therapeutics. These models revealed that bortezomib induces several transcriptional programs in dorsal root ganglia that result in the activation of different neuroinflammatory pathways and secondary central sensitization. In contrast, vincristine has direct toxic effects on the axon, which are accompanied by changes similar to those observed after nerve cut. Axon degeneration following both vincristine and bortezomib is mediated by a phylogenetically ancient, genetically encoded axon destruction program that leads to the activation of the Toll-like receptor adaptor SARM1 (sterile alpha and TIR motif containing protein 1) and local decrease of nicotinamide dinucleotide (NAD+). Here, I describe current in vitro and in vivo models of vincristine- and bortezomib induced neuropathies, present discoveries resulting from these models in the context of clinical findings and discuss how increased understanding of molecular mechanisms underlying different aspects of neuropathies can be translated to effective treatments to prevent, attenuate or reverse vincristine- and bortezomib-induced neuropathies. Such treatments could improve the quality of life of patients both during and after cancer therapy and, accordingly, have enormous societal impact.
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Affiliation(s)
- Stefanie Geisler
- Department of Neurology, Washington University School of Medicine in St. Louis, MO, USA.
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14
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Zhang Y, Wang L, Peng D, Zhang Q, Yang Q, Li J, Li D, Tang D, Chen M, Liang S, Liu Y, Wang S, Liu Z. Engineering of highly potent and selective HNTX-III mutant against hNa v1.7 sodium channel for treatment of pain. J Biol Chem 2021; 296:100326. [PMID: 33493520 PMCID: PMC7988488 DOI: 10.1016/j.jbc.2021.100326] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 01/20/2021] [Accepted: 01/21/2021] [Indexed: 11/23/2022] Open
Abstract
Human voltage-gated sodium channel Nav1.7 (hNav1.7) is involved in the generation and conduction of neuropathic and nociceptive pain signals. Compelling genetic and preclinical studies have validated that hNav1.7 is a therapeutic target for the treatment of pain; however, there is a dearth of currently available compounds capable of targeting hNav1.7 with high potency and specificity. Hainantoxin-III (HNTX-III) is a 33-residue polypeptide from the venom of the spider Ornithoctonus hainana. It is a selective antagonist of neuronal tetrodotoxin-sensitive voltage-gated sodium channels. Here, we report the engineering of improved potency and Nav selectivity of hNav1.7 inhibition peptides derived from the HNTX-III scaffold. Alanine scanning mutagenesis showed key residues for HNTX-III interacting with hNav1.7. Site-directed mutagenesis analysis indicated key residues on hNav1.7 interacting with HNTX-III. Molecular docking was conducted to clarify the binding interface between HNTX-III and Nav1.7 and guide the molecular engineering process. Ultimately, we obtained H4 [K0G1-P18K-A21L-V] based on molecular docking of HNTX-III and hNav1.7 with a 30-fold improved potency (IC50 0.007 ± 0.001 μM) and >1000-fold selectivity against Nav1.4 and Nav1.5. H4 also showed robust analgesia in the acute and chronic inflammatory pain model and neuropathic pain model. Thus, our results provide further insight into peptide toxins that may prove useful in guiding the development of inhibitors with improved potency and selectivity for Nav subtypes with robust analgesia.
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Affiliation(s)
- Yunxiao Zhang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China; Key Laboratory of Hunan Province for Advanced Carbon-based Functional Materials, School of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang, Hunan, China
| | - Li Wang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Dezheng Peng
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China; Key Laboratory of Hunan Province for Advanced Carbon-based Functional Materials, School of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang, Hunan, China
| | - Qingfeng Zhang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Qiuchu Yang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Jiayan Li
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Dan Li
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Dongfang Tang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Minzhi Chen
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Songping Liang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Yu Liu
- Key Laboratory of Hunan Province for Advanced Carbon-based Functional Materials, School of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang, Hunan, China.
| | - Sheng Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Zhonghua Liu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China.
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15
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Feng X, Chen L, Zhou R, Bao X, Mou H, Ye L, Yang P. Blocking the Mineralocorticoid Receptor Improves Cognitive Impairment after Anesthesia/Splenectomy in Rats. Int J Med Sci 2021; 18:387-397. [PMID: 33390808 PMCID: PMC7757129 DOI: 10.7150/ijms.48767] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 11/09/2020] [Indexed: 02/05/2023] Open
Abstract
Recent mounting studies showed that neuroinflammation caused by surgery or anesthesia is closely related to postoperative cognitive dysfunction (POCD). This study investigated the effect of mineralocorticoid receptor (MR) on neuroinflammation and POCD. To detect the MR effect in an animal model, we randomly divided rats into control, anesthesia, and surgery groups. To determine whether the MR-specific blocker eplerenone (EPL) could improve cognitive dysfunction, we assigned other animals into the control, surgery and EPL treatment, and surgery groups. Cognitive function was detected using the Morris water maze. Serum cytokine levels were measured by ELISA, and the histopathological changes of hippocampal neurons were identified by hematoxylin/eosin and Nissl staining. Our research confirmed that anesthesia and surgical stimulation could lead to IL-1β, IL-6, and TNF-α activation and hippocampal neuronal degeneration and pathological damage. MR was upregulated in the hippocampus under cognitive impairment condition. Additionally, EPL could alleviate inflammatory activation and neuronal damage by exerting neuroprotective effects. The preclinical model of sevoflurane anesthesia/splenectomy implied that MR expression is upregulated by regulating the neuroinflammation in the brain under POCD condition. Manipulating the MR expression by EPL could improve the inflammation activation and neuronal damage.
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Affiliation(s)
- Xixia Feng
- Department of Pain Management, West China Hospital, Sichuan University, Chengdu, Sichuan Province, 610041, P. R. China
| | - Lu Chen
- Department of Pain Management, West China Hospital, Sichuan University, Chengdu, Sichuan Province, 610041, P. R. China
| | - Ruihao Zhou
- Department of Pain Management, West China Hospital, Sichuan University, Chengdu, Sichuan Province, 610041, P. R. China
| | - Xiuqun Bao
- Department of Anesthesiology, The First Affiliated Hospital of Chengdu Medical College, Xindu, Sichuan, 610500, P. R. China
| | - Hongxia Mou
- Department of Anesthesiology, The First Affiliated Hospital of Chengdu Medical College, Xindu, Sichuan, 610500, P. R. China
| | - Ling Ye
- Department of Pain Management, West China Hospital, Sichuan University, Chengdu, Sichuan Province, 610041, P. R. China
| | - Pingliang Yang
- Department of Anesthesiology, The First Affiliated Hospital of Chengdu Medical College, Xindu, Sichuan, 610500, P. R. China
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16
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Chen L, Huang J, Benson C, Lankford KL, Zhao P, Carrara J, Tan AM, Kocsis JD, Waxman SG, Dib-Hajj SD. Sodium channel Nav1.6 in sensory neurons contributes to vincristine-induced allodynia. Brain 2020; 143:2421-2436. [PMID: 32830219 DOI: 10.1093/brain/awaa208] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/30/2020] [Accepted: 05/08/2020] [Indexed: 12/20/2022] Open
Abstract
Vincristine, a widely used chemotherapeutic agent, produces painful peripheral neuropathy. The underlying mechanisms are not well understood. In this study, we investigated whether voltage-gated sodium channels are involved in the development of vincristine-induced neuropathy. We established a mouse model in which repeated systemic vincristine treatment results in the development of significant mechanical allodynia. Histological examinations did not reveal major structural changes at proximal sciatic nerve branches or distal toe nerve fascicles at the vincristine dose used in this study. Immunohistochemical studies and in vivo two-photon imaging confirmed that there is no significant change in density or morphology of intra-epidermal nerve terminals throughout the course of vincristine treatment. These observations suggest that nerve degeneration is not a prerequisite of vincristine-induced mechanical allodynia in this model. We also provided the first detailed characterization of tetrodotoxin-sensitive (TTX-S) and resistant (TTX-R) sodium currents in dorsal root ganglion neurons following vincristine treatment. Accompanying the behavioural hyperalgesia phenotype, voltage-clamp recordings of small and medium dorsal root ganglion neurons from vincristine-treated animals revealed a significant upregulation of TTX-S Na+ current in medium but not small neurons. The increase in TTX-S Na+ current density is likely mediated by Nav1.6, because in the absence of Nav1.6 channels, vincristine failed to alter TTX-S Na+ current density in medium dorsal root ganglion neurons and, importantly, mechanical allodynia was significantly attenuated in conditional Nav1.6 knockout mice. Our data show that TTX-S sodium channel Nav1.6 is involved in the functional changes of dorsal root ganglion neurons following vincristine treatment and it contributes to the maintenance of vincristine-induced mechanical allodynia.
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Affiliation(s)
- Lubin Chen
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Jianying Huang
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Curtis Benson
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Karen L Lankford
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Peng Zhao
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Jennifer Carrara
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Andrew M Tan
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Jeffery D Kocsis
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Sulayman D Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
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17
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Newly Discovered Action of HpTx3 from Venom of Heteropoda venatoria on Na v1.7 and Its Pharmacological Implications in Analgesia. Toxins (Basel) 2019; 11:toxins11120680. [PMID: 31757020 PMCID: PMC6950750 DOI: 10.3390/toxins11120680] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 11/17/2019] [Accepted: 11/18/2019] [Indexed: 02/07/2023] Open
Abstract
It has been reported that Heteropodatoxin3 (HpTx3), a peptidic neurotoxin purified from the venom of the spider species Heteropoda venatoria, could inhibit Kv4.2 channels. Our present study newly found that HpTx3 also has potent and selective inhibitory action on Nav1.7, with an IC50 of 135.61 ± 12.98 nM. Without effect on the current–voltage (I-V) relationship of Nav1.7, HpTx3 made minor alternation in the voltage-dependence of activation and steady-state inactivation of Nav1.7 (4.15 mV and 7.29 mV, respectively) by interacting with the extracellular S3–S4 loop (S3b–S4 sequence) in domain II and the domain IV of the Nav channel subtype, showing the characteristics of both pore blocker and gate modifier toxin. During the interaction of HpTx3 with the S3b–S4 sequence of Nav1.7, the amino acid residue D in the sequence played a key role. When administered intraperitoneally or intramuscularly, HpTx3 displayed potent analgesic activity in a dose-dependent manner in different mouse pain models induced by formalin, acetic acid, complete Freund’s adjuvant, hot plate, or spared nerve injury, demonstrating that acute, inflammatory, and neuropathic pains were all effectively inhibited by the toxin. In most cases HpTx3 at doses of ≥ 1mg/kg could produce the analgesic effect comparable to that of 1 mg/kg morphine. These results suggest that HpTx3 not only can be used as a molecular probe to investigate ion channel function and pain mechanism, but also has potential in the development of the drugs that treat the Nav1.7 channel-related pain.
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18
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Spider Knottin Pharmacology at Voltage-Gated Sodium Channels and Their Potential to Modulate Pain Pathways. Toxins (Basel) 2019; 11:toxins11110626. [PMID: 31671792 PMCID: PMC6891507 DOI: 10.3390/toxins11110626] [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: 09/24/2019] [Revised: 10/24/2019] [Accepted: 10/24/2019] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated sodium channels (NaVs) are a key determinant of neuronal signalling. Neurotoxins from diverse taxa that selectively activate or inhibit NaV channels have helped unravel the role of NaV channels in diseases, including chronic pain. Spider venoms contain the most diverse array of inhibitor cystine knot (ICK) toxins (knottins). This review provides an overview on how spider knottins modulate NaV channels and describes the structural features and molecular determinants that influence their affinity and subtype selectivity. Genetic and functional evidence support a major involvement of NaV subtypes in various chronic pain conditions. The exquisite inhibitory properties of spider knottins over key NaV subtypes make them the best lead molecules for the development of novel analgesics to treat chronic pain.
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19
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Abstract
Acute pain is adaptive, but chronic pain is a global challenge. Many chronic pain syndromes are peripheral in origin and reflect hyperactivity of peripheral pain-signaling neurons. Current treatments are ineffective or only partially effective and in some cases can be addictive, underscoring the need for better therapies. Molecular genetic studies have now linked multiple human pain disorders to voltage-gated sodium channels, including disorders characterized by insensitivity or reduced sensitivity to pain and others characterized by exaggerated pain in response to normally innocuous stimuli. Here, we review recent developments that have enhanced our understanding of pathophysiological mechanisms in human pain and advances in targeting sodium channels in peripheral neurons for the treatment of pain using novel and existing sodium channel blockers.
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Affiliation(s)
- Sulayman D Dib-Hajj
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut 06510, USA; .,Rehabilitation Research Center, Veterans Affairs, Connecticut Healthcare System, West Haven, Connecticut 06516, USA
| | - Stephen G Waxman
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut 06510, USA; .,Rehabilitation Research Center, Veterans Affairs, Connecticut Healthcare System, West Haven, Connecticut 06516, USA
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20
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µ-TRTX-Ca1a: a novel neurotoxin from Cyriopagopus albostriatus with analgesic effects. Acta Pharmacol Sin 2019; 40:859-866. [PMID: 30382183 DOI: 10.1038/s41401-018-0181-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 09/30/2018] [Indexed: 12/16/2022] Open
Abstract
Human genetic and pharmacological studies have demonstrated that voltage-gated sodium channels (VGSCs) are promising therapeutic targets for the treatment of pain. Spider venom contains many toxins that modulate the activity of VGSCs. To date, only 0.01% of such spider toxins has been explored, and thus there is a great potential for discovery of novel VGSC modulators as useful pharmacological tools or potential therapeutics. In the current study, we identified a novel peptide, µ-TRTX-Ca1a (Ca1a), in the venom of the tarantula Cyriopagopus albostriatus. This peptide consisted of 38 residues, including 6 cysteines, i.e. IFECSISCEIEKEGNGKKCKPKKCKGGWKCKFNICVKV. In HEK293T or ND7/23 cells expressing mammalian VGSCs, this peptide exhibited the strongest inhibitory activity on Nav1.7 (IC50 378 nM), followed by Nav1.6 (IC50 547 nM), Nav1.2 (IC50 728 nM), Nav1.3 (IC50 2.2 µM) and Nav1.4 (IC50 3.2 µM), and produced negligible inhibitory effect on Nav1.5, Nav1.8, and Nav1.9, even at high concentrations of up to 10 µM. Furthermore, this peptide did not significantly affect the activation and inactivation of Nav1.7. Using site-directed mutagenesis of Nav1.7 and Nav1.4, we revealed that its binding site was localized to the DIIS3-S4 linker region involving the D816 and E818 residues. In three different mouse models of pain, pretreatment with Cala (100, 200, 500 µg/kg) dose-dependently suppressed the nociceptive responses induced by formalin, acetic acid or heat. These results suggest that Ca1a is a novel neurotoxin against VGSCs and has a potential to be developed as a novel analgesic.
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21
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de la Peña JBI, Song JJ, Campbell ZT. RNA control in pain: Blame it on the messenger. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1546. [PMID: 31090211 DOI: 10.1002/wrna.1546] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 04/17/2019] [Accepted: 04/22/2019] [Indexed: 12/12/2022]
Abstract
mRNA function is meticulously controlled. We provide an overview of the integral role that posttranscriptional controls play in the perception of painful stimuli by sensory neurons. These specialized cells, termed nociceptors, precisely regulate mRNA polarity, translation, and stability. A growing body of evidence has revealed that targeted disruption of mRNAs and RNA-binding proteins robustly diminishes pain-associated behaviors. We propose that the use of multiple independent regulatory paradigms facilitates robust temporal and spatial precision of protein expression in response to a range of pain-promoting stimuli. This article is categorized under: RNA in Disease and Development > RNA in Disease Translation > Translation Regulation RNA Turnover and Surveillance > Regulation of RNA Stability.
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Affiliation(s)
- June Bryan I de la Peña
- Department of Biological Sciences and the Center for Advanced Pain Studies, University of Texas, Dallas, Richardson, Texas
| | - Jane J Song
- Department of Biological Sciences and the Center for Advanced Pain Studies, University of Texas, Dallas, Richardson, Texas
| | - Zachary T Campbell
- Department of Biological Sciences and the Center for Advanced Pain Studies, University of Texas, Dallas, Richardson, Texas
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22
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Israel MR, Tanaka BS, Castro J, Thongyoo P, Robinson SD, Zhao P, Deuis JR, Craik DJ, Durek T, Brierley SM, Waxman SG, Dib-Hajj SD, Vetter I. Na V 1.6 regulates excitability of mechanosensitive sensory neurons. J Physiol 2019; 597:3751-3768. [PMID: 31087362 DOI: 10.1113/jp278148] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 05/08/2019] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Voltage-gated sodium channels are critical for peripheral sensory neuron transduction and have been implicated in a number of painful and painless disorders. The β-scorpion toxin, Cn2, is selective for NaV 1.6 in dorsal root ganglion neurons. NaV 1.6 plays an essential role in peripheral sensory neurons, specifically at the distal terminals of mechanosensing fibres innervating the skin and colon. NaV 1.6 activation also leads to enhanced response to mechanical stimulus in vivo. This works highlights the use of toxins in elucidating pain pathways moreover the importance of non-peripherally restricted NaV isoforms in pain generation. ABSTRACT Peripheral sensory neurons express multiple voltage-gated sodium channels (NaV ) critical for the initiation and propagation of action potentials and transmission of sensory input. Three pore-forming sodium channel isoforms are primarily expressed in the peripheral nervous system (PNS): NaV 1.7, NaV 1.8 and NaV 1.9. These sodium channels have been implicated in painful and painless channelopathies and there has been intense interest in them as potential therapeutic targets in human pain. Emerging evidence suggests NaV 1.6 channels are an important isoform in pain sensing. This study aimed to assess, using pharmacological approaches, the function of NaV 1.6 channels in peripheral sensory neurons. The potent and NaV 1.6 selective β-scorpion toxin Cn2 was used to assess the effect of NaV 1.6 channel activation in the PNS. The multidisciplinary approach included Ca2+ imaging, whole-cell patch-clamp recordings, skin-nerve and gut-nerve preparations and in vivo behavioural assessment of pain. Cn2 facilitates NaV 1.6 early channel opening, and increased persistent and resurgent currents in large-diameter dorsal root ganglion (DRG) neurons. This promotes enhanced excitatory drive and tonic action potential firing in these neurons. In addition, NaV 1.6 channel activation in the skin and gut leads to increased response to mechanical stimuli. Finally, intra-plantar injection of Cn2 causes mechanical but not thermal allodynia. This study confirms selectivity of Cn2 on NaV 1.6 channels in sensory neurons. Activation of NaV 1.6 channels, in terminals of the skin and viscera, leads to profound changes in neuronal responses to mechanical stimuli. In conclusion, sensory neurons expressing NaV 1.6 are important for the transduction of mechanical information in sensory afferents innervating the skin and viscera.
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Affiliation(s)
- Mathilde R Israel
- IMB Centre for Pain Research, Institute for Molecular Bioscience, 306 Carmody Rd (Building 80), University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Brian S Tanaka
- Center for Neuroscience and Regeneration Research, Yale School of Medicine, New Haven, CT, 06510, USA.,Department of Neurology, Yale School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Joel Castro
- Visceral Pain Research Group, Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Bedford Park, South Australia, 5042, Australia.,Hopwood Centre for Neurobiology and Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, 5000, Australia
| | - Panumart Thongyoo
- IMB Centre for Pain Research, Institute for Molecular Bioscience, 306 Carmody Rd (Building 80), University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Samuel D Robinson
- IMB Centre for Pain Research, Institute for Molecular Bioscience, 306 Carmody Rd (Building 80), University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Peng Zhao
- Center for Neuroscience and Regeneration Research, Yale School of Medicine, New Haven, CT, 06510, USA.,Department of Neurology, Yale School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Jennifer R Deuis
- IMB Centre for Pain Research, Institute for Molecular Bioscience, 306 Carmody Rd (Building 80), University of Queensland, Brisbane, Queensland, 4072, Australia
| | - David J Craik
- IMB Centre for Pain Research, Institute for Molecular Bioscience, 306 Carmody Rd (Building 80), University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Thomas Durek
- IMB Centre for Pain Research, Institute for Molecular Bioscience, 306 Carmody Rd (Building 80), University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Stuart M Brierley
- Visceral Pain Research Group, Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Bedford Park, South Australia, 5042, Australia.,Hopwood Centre for Neurobiology and Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, South Australia, 5000, Australia
| | - Stephen G Waxman
- Center for Neuroscience and Regeneration Research, Yale School of Medicine, New Haven, CT, 06510, USA.,Department of Neurology, Yale School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Sulayman D Dib-Hajj
- Center for Neuroscience and Regeneration Research, Yale School of Medicine, New Haven, CT, 06510, USA.,Department of Neurology, Yale School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Irina Vetter
- IMB Centre for Pain Research, Institute for Molecular Bioscience, 306 Carmody Rd (Building 80), University of Queensland, Brisbane, Queensland, 4072, Australia.,School of Pharmacy, Pharmacy Australia Centre of Excellence, 20 Cornwall St, Woolloongabba, Queensland, 4102, Australia
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23
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Abstract
Obesity is often associated with increased pain, but little is known about the effects of obesity and diet on postoperative pain. In this study, effects of diet and obesity were examined in the paw incision model, a preclinical model of postoperative pain. Long-Evans rats were fed high-fat diet (40% calories from butter fat) or low-fat normal chow. Male rats fed high-fat diet starting 6 weeks before incision (a diet previously shown to induce markers of obesity) had prolonged mechanical hypersensitivity and an overall increase in spontaneous pain in response to paw incision, compared with normal chow controls. Diet effects in females were minor. Removing high-fat diet for 2 weeks before incision reversed the diet effects on pain behaviors, although this was not enough time to reverse high-fat diet-induced weight gain. A shorter (1 week) exposure to high-fat diet before incision also increased pain behaviors in males, albeit to a lesser degree. The 6-week high-fat diet increased macrophage density as examined immunohistochemically in lumbar dorsal root ganglion even before paw incision, especially in males, and sensitized responses of peritoneal macrophages to lipopolysaccharide stimuli in vitro. The nerve regeneration marker growth-associated protein 43 (GAP43) in skin near the incision (day 4) was higher in the high-fat diet group, and wound healing was delayed. In summary, high-fat diet increased postoperative pain particularly in males, but some diet effects did not depend on weight gain. Even short-term dietary manipulations, that do not affect obesity, may enhance postoperative pain.
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Maatuf Y, Geron M, Priel A. The Role of Toxins in the Pursuit for Novel Analgesics. Toxins (Basel) 2019; 11:toxins11020131. [PMID: 30813430 PMCID: PMC6409898 DOI: 10.3390/toxins11020131] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 02/17/2019] [Accepted: 02/20/2019] [Indexed: 12/19/2022] Open
Abstract
Chronic pain is a major medical issue which reduces the quality of life of millions and inflicts a significant burden on health authorities worldwide. Currently, management of chronic pain includes first-line pharmacological therapies that are inadequately effective, as in just a portion of patients pain relief is obtained. Furthermore, most analgesics in use produce severe or intolerable adverse effects that impose dose restrictions and reduce compliance. As the majority of analgesic agents act on the central nervous system (CNS), it is possible that blocking pain at its source by targeting nociceptors would prove more efficient with minimal CNS-related side effects. The development of such analgesics requires the identification of appropriate molecular targets and thorough understanding of their structural and functional features. To this end, plant and animal toxins can be employed as they affect ion channels with high potency and selectivity. Moreover, elucidation of the toxin-bound ion channel structure could generate pharmacophores for rational drug design while favorable safety and analgesic profiles could highlight toxins as leads or even as valuable therapeutic compounds themselves. Here, we discuss the use of plant and animal toxins in the characterization of peripherally expressed ion channels which are implicated in pain.
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Affiliation(s)
- Yossi Maatuf
- The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel.
| | - Matan Geron
- The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel.
| | - Avi Priel
- The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel.
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Role of Na V1.6 and Na Vβ4 Sodium Channel Subunits in a Rat Model of Low Back Pain Induced by Compression of the Dorsal Root Ganglia. Neuroscience 2019; 402:51-65. [PMID: 30699332 DOI: 10.1016/j.neuroscience.2019.01.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/08/2019] [Accepted: 01/11/2019] [Indexed: 01/18/2023]
Abstract
Low back pain is a common cause of chronic pain and disability. It is modeled in rodents by chronically compressing the lumbar dorsal root ganglia (DRG) with small metal rods, resulting in ipsilateral mechanical and cold hypersensitivity, and hyperexcitability of sensory neurons. Sodium channels are implicated in this hyperexcitability, but the responsible isoforms are unknown. In this study, we used siRNA-mediated knockdown of the pore-forming NaV1.6 and regulatory NaVβ4 sodium channel isoforms that have been previously implicated in a different model of low back pain caused by locally inflaming the L5 DRG. Knockdown of either subunit markedly reduced spontaneous pain and mechanical and cold hypersensitivity induced by DRG compression, and reduced spontaneous activity and hyperexcitability of sensory neurons with action potentials <1.5 msec (predominately cells with myelinated axons, based on conduction velocities measured in a subset of cells) 4 days after DRG compression. These results were similar to those previously obtained in the DRG inflammation model and some neuropathic pain models, in which sensory neurons other than nociceptors seem to play key roles. The cytokine profiles induced by DRG compression and DRG inflammation were also very similar, with upregulation of several type 1 pro-inflammatory cytokines and downregulation of type 2 anti-inflammatory cytokines. Surprisingly, the cytokine profile was largely unaffected by NaVβ4 knockdown in either model. The NaV1.6 channel, and the NaVβ4 subunit that can regulate NaV1.6 to enhance repetitive firing, play key roles in both models of low back pain; targeting the abnormal spontaneous activity they generate may have therapeutic value.
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26
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Increased Resurgent Sodium Currents in Nav1.8 Contribute to Nociceptive Sensory Neuron Hyperexcitability Associated with Peripheral Neuropathies. J Neurosci 2019; 39:1539-1550. [PMID: 30617209 DOI: 10.1523/jneurosci.0468-18.2018] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 10/22/2018] [Accepted: 11/25/2018] [Indexed: 11/21/2022] Open
Abstract
Neuropathic pain is a significant public health challenge, yet the underlying mechanisms remain poorly understood. Painful small fiber neuropathy (SFN) may be caused by gain-of-function mutations in Nav1.8, a sodium channel subtype predominantly expressed in peripheral nociceptive neurons. However, it is not clear how Nav1.8 disease mutations induce sensory neuron hyperexcitability. Here we studied two mutations in Nav1.8 associated with hypersensitive sensory neurons: G1662S reported in painful SFN; and T790A, which underlies increased pain behaviors in the Possum transgenic mouse strain. We show that, in male DRG neurons, these mutations, which impair inactivation, significantly increase TTX-resistant resurgent sodium currents mediated by Nav1.8. The G1662S mutation doubled resurgent currents, and the T790A mutation increased them fourfold. These unusual currents are typically evoked during the repolarization phase of action potentials. We show that the T790A mutation greatly enhances DRG neuron excitability by reducing current threshold and increasing firing frequency. Interestingly, the mutation endows DRG neurons with multiple early afterdepolarizations and leads to substantial prolongation of action potential duration. In DRG neurons, siRNA knockdown of sodium channel β4 subunits fails to significantly alter T790A current density but reduces TTX-resistant resurgent currents by 56%. Furthermore, DRG neurons expressing T790A channels exhibited reduced excitability with fewer early afterdepolarizations and narrower action potentials after β4 knockdown. Together, our data demonstrate that open-channel block of TTX-resistant currents, enhanced by gain-of-function mutations in Nav1.8, can make major contributions to the hyperexcitability of nociceptive neurons, likely leading to altered sensory phenotypes including neuropathic pain in SFN.SIGNIFICANCE STATEMENT This work demonstrates that two disease mutations in the voltage-gated sodium channel Nav1.8 that induce nociceptor hyperexcitability increase resurgent currents. Nav1.8 is crucial for pain sensations. Because resurgent currents are evoked during action potential repolarization, they can be crucial regulators of action potential activity. Our data indicate that increased Nav1.8 resurgent currents in DRG neurons greatly prolong action potential duration and enhance repetitive firing. We propose that Nav1.8 open-channel block is a major factor in Nav1.8-associated pain mechanisms and that targeting the molecular mechanism underlying these unique resurgent currents represents a novel therapeutic target for the treatment of aberrant pain sensations.
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27
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28
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Yang Z, Tan Q, Cheng D, Zhang L, Zhang J, Gu EW, Fang W, Lu X, Liu X. The Changes of Intrinsic Excitability of Pyramidal Neurons in Anterior Cingulate Cortex in Neuropathic Pain. Front Cell Neurosci 2018; 12:436. [PMID: 30519160 PMCID: PMC6258991 DOI: 10.3389/fncel.2018.00436] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 11/05/2018] [Indexed: 12/13/2022] Open
Abstract
To find satisfactory treatment strategies for neuropathic pain syndromes, the cellular mechanisms should be illuminated. Central sensitization is a generator of pain hypersensitivity, and is mainly reflected in neuronal hyperexcitability in pain pathway. Neuronal excitability depends on two components, the synaptic inputs and the intrinsic excitability. Previous studies have focused on the synaptic plasticity in different forms of pain. But little is known about the changes of neuronal intrinsic excitability in neuropathic pain. To address this question, whole-cell patch clamp recordings were performed to study the synaptic transmission and neuronal intrinsic excitability 1 week after spared nerve injury (SNI) or sham operation in male C57BL/6J mice. We found increased spontaneous excitatory postsynaptic currents (sEPSC) frequency in layer II/III pyramidal neurons of anterior cingulate cortex (ACC) from mice with neuropathic pain. Elevated intrinsic excitability of these neurons after nerve injury was also picked up, which was reflected in gain of input-output curve, inter-spike interval (ISI), spike threshold and Refractory period (RP). Besides firing rate related to neuronal intrinsic excitability, spike timing also plays an important role in neural information processing. The precision of spike timing measured by standard deviation of spike timing (SDST) was decreased in neuropathic pain state. The electrophysiological studies revealed the elevated intrinsic excitation in layer II/III pyramidal neurons of ACC in mice with neuropathic pain, which might contribute to central excitation.
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Affiliation(s)
- Zhilai Yang
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Qilian Tan
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Dan Cheng
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Lei Zhang
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Jiqian Zhang
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Er-Wei Gu
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Weiping Fang
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Xianfu Lu
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
| | - Xuesheng Liu
- Department of Anesthesiology, First Affiliated Hospital, Anhui Medical University, Hefei, China
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29
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Odem MA, Bavencoffe AG, Cassidy RM, Lopez ER, Tian J, Dessauer CW, Walters ET. Isolated nociceptors reveal multiple specializations for generating irregular ongoing activity associated with ongoing pain. Pain 2018; 159:2347-2362. [PMID: 30015712 PMCID: PMC6193853 DOI: 10.1097/j.pain.0000000000001341] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Ongoing pain has been linked to ongoing activity (OA) in human C-fiber nociceptors, but rodent models of pain-related OA have concentrated on allodynia rather than ongoing pain, and on OA generated in non-nociceptive Aβ fibers rather than C-fiber nociceptors. Little is known about how ongoing pain or nociceptor OA is generated. To define neurophysiological alterations underlying nociceptor OA, we have used isolated dorsal root ganglion neurons that continue to generate OA after removal from animals displaying ongoing pain. We subclassify OA as either spontaneous activity generated solely by alterations intrinsic to the active neuron or as extrinsically driven OA. Both types of OA were implicated previously in nociceptors in vivo and after isolation following spinal cord injury, which produces chronic ongoing pain. Using novel automated algorithms to analyze irregular changes in membrane potential, we have found, in a distinctive, nonaccommodating type of probable nociceptor, induction by spinal cord injury of 3 alterations that promote OA: (1) prolonged depolarization of resting membrane potential, (2) a hyperpolarizing shift in the voltage threshold for action potential generation, and (3) an increase in the incidence of large depolarizing spontaneous fluctuations (DSFs). Can DSFs also be enhanced acutely to promote OA in neurons from uninjured animals? A low dose of serotonin failed to change resting membrane potential but lowered action potential threshold. When combined with artificial depolarization to model inflammation, serotonin also strongly potentiated DSFs and OA. These findings reveal nociceptor specializations for generating OA that may promote ongoing pain in chronic and acute conditions.
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Affiliation(s)
- Max A. Odem
- Department of Integrative Biology and Pharmacology, McGovern Medical School at UTHealth, Houston, TX, USA
| | - Alexis G. Bavencoffe
- Department of Integrative Biology and Pharmacology, McGovern Medical School at UTHealth, Houston, TX, USA
| | - Ryan M. Cassidy
- Department of Integrative Biology and Pharmacology, McGovern Medical School at UTHealth, Houston, TX, USA
| | - Elia R. Lopez
- Department of Integrative Biology and Pharmacology, McGovern Medical School at UTHealth, Houston, TX, USA
| | - Jinbin Tian
- Department of Integrative Biology and Pharmacology, McGovern Medical School at UTHealth, Houston, TX, USA
| | - Carmen W. Dessauer
- Department of Integrative Biology and Pharmacology, McGovern Medical School at UTHealth, Houston, TX, USA
| | - Edgar T. Walters
- Department of Integrative Biology and Pharmacology, McGovern Medical School at UTHealth, Houston, TX, USA
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30
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Zhang Y, Peng D, Huang B, Yang Q, Zhang Q, Chen M, Rong M, Liu Z. Discovery of a Novel Na v1.7 Inhibitor From Cyriopagopus albostriatus Venom With Potent Analgesic Efficacy. Front Pharmacol 2018; 9:1158. [PMID: 30386239 PMCID: PMC6198068 DOI: 10.3389/fphar.2018.01158] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 09/24/2018] [Indexed: 01/15/2023] Open
Abstract
Spider venoms contain a vast array of bioactive peptides targeting ion channels. A large number of peptides have high potency and selectivity toward sodium channels. Nav1.7 contributes to action potential generation and propagation and participates in pain signaling pathway. In this study, we describe the identification of μ-TRTX-Ca2a (Ca2a), a novel 35-residue peptide from the venom of Vietnam spider Cyriopagopus albostriatus (C. albostriatus) that potently inhibits Nav1.7 (IC50 = 98.1 ± 3.3 nM) with high selectivity against skeletal muscle isoform Nav1.4 (IC50 > 10 μM) and cardiac muscle isoform Nav1.5 (IC50 > 10 μM). Ca2a did not significantly alter the voltage-dependent activation or fast inactivation of Nav1.7, but it hyperpolarized the slow inactivation. Site-directed mutagenesis analysis indicated that Ca2a bound with Nav1.7 at the extracellular S3–S4 linker of domain II. Meanwhile, Ca2a dose-dependently attenuated pain behaviors in rodent models of formalin-induced paw licking, hot plate test, and acetic acid-induced writhing. This study indicates that Ca2a is a potential lead molecule for drug development of novel analgesics.
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Affiliation(s)
- Yunxiao Zhang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Dezheng Peng
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Biao Huang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Qiuchu Yang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Qingfeng Zhang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Minzhi Chen
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Mingqiang Rong
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Zhonghua Liu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
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31
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Gonçalves TC, Benoit E, Partiseti M, Servent D. The Na V1.7 Channel Subtype as an Antinociceptive Target for Spider Toxins in Adult Dorsal Root Ganglia Neurons. Front Pharmacol 2018; 9:1000. [PMID: 30233376 PMCID: PMC6131673 DOI: 10.3389/fphar.2018.01000] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/14/2018] [Indexed: 12/11/2022] Open
Abstract
Although necessary for human survival, pain may sometimes become pathologic if long-lasting and associated with alterations in its signaling pathway. Opioid painkillers are officially used to treat moderate to severe, and even mild, pain. However, the consequent strong and not so rare complications that occur, including addiction and overdose, combined with pain management costs, remain an important societal and economic concern. In this context, animal venom toxins represent an original source of antinociceptive peptides that mainly target ion channels (such as ASICs as well as TRP, CaV, KV and NaV channels) involved in pain transmission. The present review aims to highlight the NaV1.7 channel subtype as an antinociceptive target for spider toxins in adult dorsal root ganglia neurons. It will detail (i) the characteristics of these primary sensory neurons, the first ones in contact with pain stimulus and conveying the nociceptive message, (ii) the electrophysiological properties of the different NaV channel subtypes expressed in these neurons, with a particular attention on the NaV1.7 subtype, an antinociceptive target of choice that has been validated by human genetic evidence, and (iii) the features of spider venom toxins, shaped of inhibitory cysteine knot motif, that present high affinity for the NaV1.7 subtype associated with evidenced analgesic efficacy in animal models.
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Affiliation(s)
- Tânia C Gonçalves
- Sanofi R&D, Integrated Drug Discovery - High Content Biology, Paris, France.,Service d'Ingénierie Moléculaire des Protéines, CEA de Saclay, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Evelyne Benoit
- Service d'Ingénierie Moléculaire des Protéines, CEA de Saclay, Université Paris-Saclay, Gif-sur-Yvette, France.,Institut des Neurosciences Paris-Saclay, UMR CNRS/Université Paris-Sud 9197, Gif-sur-Yvette, France
| | - Michel Partiseti
- Sanofi R&D, Integrated Drug Discovery - High Content Biology, Paris, France
| | - Denis Servent
- Service d'Ingénierie Moléculaire des Protéines, CEA de Saclay, Université Paris-Saclay, Gif-sur-Yvette, France
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32
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Tao J, Jiang F, Liu C, Liu Z, Zhu Y, Xu J, Ge Y, Xu K, Yin P. Modulatory effects of bufalin, an active ingredient from toad venom on voltage-gated sodium channels. Mol Biol Rep 2018; 45:721-740. [PMID: 29931533 DOI: 10.1007/s11033-018-4213-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 06/11/2018] [Indexed: 12/22/2022]
Abstract
Chan-su (toad venom) has been used as an analgesic agent in China from ancient to modern times. Bufalin, a non-peptide toxin extracted from toad venom, is considered as one of the analgesic components. The molecular mechanism underlying the anti-nociceptive effects of bufalin remains unclear so far. In this study, we investigated the pharmacological effects of bufalin on pain-related ion channels as well as animal models through patch clamping, calcium imaging and animal behavior observation. Using the whole-cell recording, bufalin caused remarkable suppressive effect on the peak currents of Nav channels (voltage gated sodium channels, VGSCs) of dorsal root ganglion neuroblastomas (ND7-23 cell) in a dose-dependent manner. Bufalin facilitated the voltage-dependent activation and induced a negative shift on the fast inactivation of VGSCs. The recovery kinetics of VGSCs were significantly slowed and the recovery proportion were reduced after administering bufalin. However, bufalin prompted no significant effect not only on Kv4.2, Kv4.3 and BK channels heterologously expressed in HEK293T cells, but also on the capsaicin and allyl isothiocyanate induced Ca2+ influx. What's more, bufalin could observably relieve formalin-induced spontaneous flinching and licking response as well as carrageenan-induced thermal and mechanical hyperalgesia in dose-dependent manner in agreement with the results of in vitro experiments. The present results imply that the remarkable anti-nociceptive effects produced by bufalin are probably ascribed to its specific regulation on Nav channels. Bufalin inhibits the Nav channels in a dose-dependent manner, which will provide references for the optimal dose selection of analgesia drugs.
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Affiliation(s)
- Jie Tao
- Department of Central Laboratory and Neurosurgery, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
| | - Feng Jiang
- Xinhua Hospital (Chongming) Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai Chongming Xinhua Translational Medical Institute for Cancer Pain, Shanghai, China
| | - Cheng Liu
- Department of Central Laboratory and Neurosurgery, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Zhirui Liu
- Department of Pharmacology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yudan Zhu
- Department of Central Laboratory and Neurosurgery, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Jian Xu
- Department of Central Laboratory and Neurosurgery, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yiqin Ge
- Department of Central Laboratory and Neurosurgery, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Kan Xu
- Department of Central Laboratory and Neurosurgery, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
| | - Peihao Yin
- Department of Central Laboratory and Neurosurgery, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
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33
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Zhang XL, Ding HH, Xu T, Liu M, Ma C, Wu SL, Wei JY, Liu CC, Zhang SB, Xin WJ. Palmitoylation of δ-catenin promotes kinesin-mediated membrane trafficking of Nav1.6 in sensory neurons to promote neuropathic pain. Sci Signal 2018; 11:11/523/eaar4394. [PMID: 29588412 DOI: 10.1126/scisignal.aar4394] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Xiao-Long Zhang
- Neuroscience Program, Zhongshan School of Medicine, The Fifth Affiliated Hospital of Sun Yat-sen University, Sun Yat-sen University, Guangzhou 510080, China
- Guangdong Province Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Huan-Huan Ding
- Neuroscience Program, Zhongshan School of Medicine, The Fifth Affiliated Hospital of Sun Yat-sen University, Sun Yat-sen University, Guangzhou 510080, China
- Guangdong Province Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Ting Xu
- Neuroscience Program, Zhongshan School of Medicine, The Fifth Affiliated Hospital of Sun Yat-sen University, Sun Yat-sen University, Guangzhou 510080, China
- Guangdong Province Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Meng Liu
- Neuroscience Program, Zhongshan School of Medicine, The Fifth Affiliated Hospital of Sun Yat-sen University, Sun Yat-sen University, Guangzhou 510080, China
- Guangdong Province Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Chao Ma
- Department of Rehabilitation Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Shao-Ling Wu
- Department of Rehabilitation Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Jia-You Wei
- Neuroscience Program, Zhongshan School of Medicine, The Fifth Affiliated Hospital of Sun Yat-sen University, Sun Yat-sen University, Guangzhou 510080, China
- Guangdong Province Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Cui-Cui Liu
- Department of Rehabilitation Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Su-Bo Zhang
- Department of Rehabilitation Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Wen-Jun Xin
- Neuroscience Program, Zhongshan School of Medicine, The Fifth Affiliated Hospital of Sun Yat-sen University, Sun Yat-sen University, Guangzhou 510080, China.
- Guangdong Province Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
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34
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Chen L, Huang J, Zhao P, Persson AK, Dib-Hajj FB, Cheng X, Tan A, Waxman SG, Dib-Hajj SD. Conditional knockout of Na V1.6 in adult mice ameliorates neuropathic pain. Sci Rep 2018; 8:3845. [PMID: 29497094 PMCID: PMC5832877 DOI: 10.1038/s41598-018-22216-w] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 02/19/2018] [Indexed: 01/09/2023] Open
Abstract
Voltage-gated sodium channels NaV1.7, NaV1.8 and NaV1.9 have been the focus for pain studies because their mutations are associated with human pain disorders, but the role of NaV1.6 in pain is less understood. In this study, we selectively knocked out NaV1.6 in dorsal root ganglion (DRG) neurons, using NaV1.8-Cre directed or adeno-associated virus (AAV)-Cre mediated approaches, and examined the specific contribution of NaV1.6 to the tetrodotoxin-sensitive (TTX-S) current in these neurons and its role in neuropathic pain. We report here that NaV1.6 contributes up to 60% of the TTX-S current in large, and 34% in small DRG neurons. We also show NaV1.6 accumulates at nodes of Ranvier within the neuroma following spared nerve injury (SNI). Although NaV1.8-Cre driven NaV1.6 knockout does not alter acute, inflammatory or neuropathic pain behaviors, AAV-Cre mediated NaV1.6 knockout in adult mice partially attenuates SNI-induced mechanical allodynia. Additionally, AAV-Cre mediated NaV1.6 knockout, mostly in large DRG neurons, significantly attenuates excitability of these neurons after SNI and reduces NaV1.6 accumulation at nodes of Ranvier at the neuroma. Together, NaV1.6 in NaV1.8-positive neurons does not influence pain thresholds under normal or pathological conditions, but NaV1.6 in large NaV1.8-negative DRG neurons plays an important role in neuropathic pain.
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Affiliation(s)
- Lubin Chen
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Jianying Huang
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Peng Zhao
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Anna-Karin Persson
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Fadia B Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Xiaoyang Cheng
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Andrew Tan
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA
| | - Sulayman D Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06510, USA. .,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA. .,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, 06516, USA.
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Bang S, Yoo J, Gong X, Liu D, Han Q, Luo X, Chang W, Chen G, Im ST, Kim YH, Strong JA, Zhang MZ, Zhang JM, Lee SY, Ji RR. Differential Inhibition of Nav1.7 and Neuropathic Pain by Hybridoma-Produced and Recombinant Monoclonal Antibodies that Target Nav1.7 : Differential activities of Nav1.7-targeting monoclonal antibodies. Neurosci Bull 2018; 34:22-41. [PMID: 29333591 PMCID: PMC5799132 DOI: 10.1007/s12264-018-0203-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 12/18/2017] [Indexed: 12/21/2022] Open
Abstract
The voltage-gated Na+ channel subtype Nav1.7 is important for pain and itch in rodents and humans. We previously showed that a Nav1.7-targeting monoclonal antibody (SVmab) reduces Na+ currents and pain and itch responses in mice. Here, we investigated whether recombinant SVmab (rSVmab) binds to and blocks Nav1.7 similar to SVmab. ELISA tests revealed that SVmab was capable of binding to Nav1.7-expressing HEK293 cells, mouse DRG neurons, human nerve tissue, and the voltage-sensor domain II of Nav1.7. In contrast, rSVmab showed no or weak binding to Nav1.7 in these tests. Patch-clamp recordings showed that SVmab, but not rSVmab, markedly inhibited Na+ currents in Nav1.7-expressing HEK293 cells. Notably, electrical field stimulation increased the blocking activity of SVmab and rSVmab in Nav1.7-expressing HEK293 cells. SVmab was more effective than rSVmab in inhibiting paclitaxel-induced mechanical allodynia. SVmab also bound to human DRG neurons and inhibited their Na+ currents. Finally, potential reasons for the differential efficacy of SVmab and rSVmab and future directions are discussed.
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Affiliation(s)
- Sangsu Bang
- Department of Anesthesiology, Duke University Medical Center, 595 LaSalle St, Durham, NC, 27710, USA
| | - Jiho Yoo
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, NC, 27710, USA
| | - Xingrui Gong
- Pain Research Center, Department of Anesthesiology, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH, 45267-0531, USA
- Department of Anesthesiology, Shanghai Children's Medical Center, Shanghai, 200127, China
| | - Di Liu
- Department of Anesthesiology, Duke University Medical Center, 595 LaSalle St, Durham, NC, 27710, USA
| | - Qingjian Han
- Department of Anesthesiology, Duke University Medical Center, 595 LaSalle St, Durham, NC, 27710, USA
| | - Xin Luo
- Department of Anesthesiology, Duke University Medical Center, 595 LaSalle St, Durham, NC, 27710, USA
| | - Wonseok Chang
- Department of Anesthesiology, Duke University Medical Center, 595 LaSalle St, Durham, NC, 27710, USA
- Department of Physiology and Biophysics, College of Medicine, Eulji University, 143-5 Yongdu-Dong, Jung-Gu, Daejeon, 34824, Korea
| | - Gang Chen
- Department of Anesthesiology, Duke University Medical Center, 595 LaSalle St, Durham, NC, 27710, USA
| | - Sang-Taek Im
- Department of Physiology, College of Medicine, Gachon University, Incheon, 21999, Korea
| | - Yong Ho Kim
- Department of Anesthesiology, Duke University Medical Center, 595 LaSalle St, Durham, NC, 27710, USA
- Department of Physiology, College of Medicine, Gachon University, Incheon, 21999, Korea
| | - Judith A Strong
- Pain Research Center, Department of Anesthesiology, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH, 45267-0531, USA
| | - Ma-Zhong Zhang
- Department of Anesthesiology, Shanghai Children's Medical Center, Shanghai, 200127, China
| | - Jun-Ming Zhang
- Pain Research Center, Department of Anesthesiology, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH, 45267-0531, USA.
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, NC, 27710, USA.
| | - Ru-Rong Ji
- Department of Anesthesiology, Duke University Medical Center, 595 LaSalle St, Durham, NC, 27710, USA.
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Identification of Persistent and Resurgent Sodium Currents in Spiral Ganglion Neurons Cultured from the Mouse Cochlea. eNeuro 2017; 4:eN-NWR-0303-17. [PMID: 29138759 PMCID: PMC5684619 DOI: 10.1523/eneuro.0303-17.2017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/13/2017] [Accepted: 10/17/2017] [Indexed: 01/11/2023] Open
Abstract
In spiral ganglion neurons (SGNs), the afferent single units of the auditory nerve, high spontaneous and evoked firing rates ensure preservation of the temporal code describing the key features of incoming sound. During postnatal development, the spatiotemporal distribution of ion channel subtypes contributes to the maturation of action potential generation in SGNs, and to their ability to generate spike patterns that follow rapidly changing inputs. Here we describe tetrodotoxin (TTX)-sensitive Na+ currents in SGNs cultured from mice, whose properties may support this fast spiking behavior. A subthreshold persistent Na+ current (INaP) and a resurgent Na+ current (INaR) both emerged prior to the onset of hearing and became more prevalent as hearing matured. Navβ4 subunits, which are proposed to play a key role in mediating INaR elsewhere in the nervous system, were immunolocalized to the first heminode where spikes are generated in the auditory nerve, and to perisomatic nodes of Ranvier. ATX-II, a sea anemone toxin that slows classical Na+ channel inactivation selectively, enhanced INaP five-fold and INaR three-fold in voltage clamp recordings. In rapidly-adapting SGNs under current clamp, ATX-II increased the likelihood of firing additional action potentials. The data identify INaP and INaR as novel regulators of excitability in SGNs, and consistent with their roles in other neuronal types, we suggest that these nonclassical Na+ currents may contribute to the control of refractoriness in the auditory nerve.
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Qin S, Jiang F, Zhou Y, Zhou G, Ye P, Ji Y. Local knockdown of Nav1.6 relieves pain behaviors induced by BmK I. Acta Biochim Biophys Sin (Shanghai) 2017; 49:713-721. [PMID: 28655185 DOI: 10.1093/abbs/gmx064] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Accepted: 06/05/2017] [Indexed: 12/13/2022] Open
Abstract
Voltage-gated sodium channels (VGSCs) in peripheral nociceptive sensory neurons are critical to transmit pain signals. BmK I purified from the venom of scorpion Buthus martensi Karsch (BmK) has been demonstrated to be the primary contributor of envenomation-associated pain. However, the role of distinct VGSCs such as Nav1.6 in the induction and maintenance of pain behaviors induced by BmK I was ambiguous. Herein, using molecular and behavioral approaches we investigated the mRNA and protein expression profiles of Nav1.6 in rat DRG after intraplantar injection of BmK I and tested the pain behaviors after knockdown of Nav1.6 in BmK I-treated rats. It was shown that during induction and maintenance of pain responses induced by BmK I, the expression of Nav1.6 in DRG was found to be significantly increased at both mRNA and protein levels. The percentage of co-localization of Nav1.6 and Isolectin B4, a molecular marker of small diameter non-peptidergic DRG neurons, was increased at the maintenance phase of pain responses. Furthermore, spontaneous pain and mechanical allodynia, but not thermal hyperalgesia induced by BmK I, were significantly alleviated after knockdown of Nav1.6. These data strongly suggest that Nav1.6 plays an indispensable role in the peripheral pain hypersensitivity induced by BmK I.
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Affiliation(s)
- Shichao Qin
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai 200444, China
| | - Feng Jiang
- Shanghai Chongming Xinhua Translational Medical Institute for Cancer Pain, Shanghai 202150, China
| | - You Zhou
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai 200444, China
| | - Guokun Zhou
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai 200444, China
| | - Pin Ye
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai 200444, China
| | - Yonghua Ji
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai 200444, China
- Shanghai Chongming Xinhua Translational Medical Institute for Cancer Pain, Shanghai 202150, China
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Localized Sympathectomy Reduces Mechanical Hypersensitivity by Restoring Normal Immune Homeostasis in Rat Models of Inflammatory Pain. J Neurosci 2017; 36:8712-25. [PMID: 27535916 DOI: 10.1523/jneurosci.4118-15.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 07/09/2016] [Indexed: 12/28/2022] Open
Abstract
UNLABELLED Some forms of chronic pain are maintained or enhanced by activity in the sympathetic nervous system (SNS), but attempts to model this have yielded conflicting findings. The SNS has both pro- and anti-inflammatory effects on immunity, confounding the interpretation of experiments using global sympathectomy methods. We performed a "microsympathectomy" by cutting the ipsilateral gray rami where they entered the spinal nerves near the L4 and L5 DRG. This led to profound sustained reductions in pain behaviors induced by local DRG inflammation (a rat model of low back pain) and by a peripheral paw inflammation model. Effects of microsympathectomy were evident within one day, making it unlikely that blocking sympathetic sprouting in the local DRGs or hindpaw was the sole mechanism. Prior microsympathectomy greatly reduced hyperexcitability of sensory neurons induced by local DRG inflammation observed 4 d later. Microsympathectomy reduced local inflammation and macrophage density in the affected tissues (as indicated by paw swelling and histochemical staining). Cytokine profiling in locally inflamed DRG showed increases in pro-inflammatory Type 1 cytokines and decreases in the Type 2 cytokines present at baseline, changes that were mitigated by microsympathectomy. Microsympathectomy was also effective in reducing established pain behaviors in the local DRG inflammation model. We conclude that the effect of sympathetic fibers in the L4/L5 gray rami in these models is pro-inflammatory. This raises the possibility that therapeutic interventions targeting gray rami might be useful in some chronic inflammatory pain conditions. SIGNIFICANCE STATEMENT Sympathetic blockade is used for many pain conditions, but preclinical studies show both pro- and anti-nociceptive effects. The sympathetic nervous system also has both pro- and anti-inflammatory effects on immune tissues and cells. We examined effects of a very localized sympathectomy. By cutting the gray rami to the spinal nerves near the lumbar sensory ganglia, we avoided widespread sympathetic denervation. This procedure profoundly reduced mechanical pain behaviors induced by a back pain model and a model of peripheral inflammatory pain. One possible mechanism was reduction of inflammation in the sympathetically denervated regions. This raises the possibility that therapeutic interventions targeting gray rami might be useful in some inflammatory conditions.
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Namer B, Ørstavik K, Schmidt R, Mair N, Kleggetveit IP, Zeidler M, Martha T, Jorum E, Schmelz M, Kalpachidou T, Kress M, Langeslag M. Changes in Ionic Conductance Signature of Nociceptive Neurons Underlying Fabry Disease Phenotype. Front Neurol 2017; 8:335. [PMID: 28769867 PMCID: PMC5510289 DOI: 10.3389/fneur.2017.00335] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 06/27/2017] [Indexed: 12/29/2022] Open
Abstract
The first symptom arising in many Fabry patients is neuropathic pain due to changes in small myelinated and unmyelinated fibers in the periphery, which is subsequently followed by a loss of sensory perception. Here we studied changes in the peripheral nervous system of Fabry patients and a Fabry mouse model induced by deletion of α-galactosidase A (Gla-/0). The skin innervation of Gla-/0 mice resembles that of the human Fabry patients. In Fabry diseased humans and Gla-/0 mice, we observed similar sensory abnormalities, which were also observed in nerve fiber recordings in both patients and mice. Electrophysiological recordings of cultured Gla-/0 nociceptors revealed that the conductance of voltage-gated Na+ and Ca2+ currents was decreased in Gla-/0 nociceptors, whereas the activation of voltage-gated K+ currents was at more depolarized potentials. Conclusively, we have observed that reduced sensory perception due to small-fiber degeneration coincides with altered electrophysiological properties of sensory neurons.
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Affiliation(s)
- Barbara Namer
- Department of Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen, Germany.,Department of Anesthesiology, Heidelberg University, Mannheim, Germany
| | - Kirstin Ørstavik
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital Rikshospitalet, Oslo, Norway
| | - Roland Schmidt
- Department of Clinical Neurophysiology, Uppsala University Hospital, Uppsala, Sweden
| | - Norbert Mair
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Inge Petter Kleggetveit
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital Rikshospitalet, Oslo, Norway
| | - Maximillian Zeidler
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Theresa Martha
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Ellen Jorum
- Department of Anesthesiology, Heidelberg University, Mannheim, Germany.,Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Martin Schmelz
- Department of Anesthesiology, Heidelberg University, Mannheim, Germany
| | - Theodora Kalpachidou
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Michaela Kress
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Michiel Langeslag
- Department of Physiology and Medical Physics, Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria
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Expression and Role of Voltage-Gated Sodium Channels in Human Dorsal Root Ganglion Neurons with Special Focus on Nav1.7, Species Differences, and Regulation by Paclitaxel. Neurosci Bull 2017; 34:4-12. [PMID: 28424991 PMCID: PMC5648619 DOI: 10.1007/s12264-017-0132-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/08/2017] [Indexed: 12/20/2022] Open
Abstract
Voltage-gated sodium channels (Navs) play an important role in human pain sensation. However, the expression and role of Nav subtypes in native human sensory neurons are unclear. To address this issue, we obtained human dorsal root ganglion (hDRG) tissues from healthy donors. PCR analysis of seven DRG-expressed Nav subtypes revealed that the hDRG has higher expression of Nav1.7 (~50% of total Nav expression) and lower expression of Nav1.8 (~12%), whereas the mouse DRG has higher expression of Nav1.8 (~45%) and lower expression of Nav1.7 (~18%). To mimic Nav regulation in chronic pain, we treated hDRG neurons in primary cultures with paclitaxel (0.1–1 μmol/L) for 24 h. Paclitaxel increased the Nav1.7 but not Nav1.8 expression and also increased the transient Na+ currents and action potential firing frequency in small-diameter (<50 μm) hDRG neurons. Thus, the hDRG provides a translational model in which to study “human pain in a dish” and test new pain therapeutics.
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Walters ET. How is chronic pain related to sympathetic dysfunction and autonomic dysreflexia following spinal cord injury? Auton Neurosci 2017; 209:79-89. [PMID: 28161248 DOI: 10.1016/j.autneu.2017.01.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/24/2017] [Accepted: 01/25/2017] [Indexed: 12/29/2022]
Abstract
Autonomic dysreflexia (AD) and neuropathic pain occur after severe injury to higher levels of the spinal cord. Mechanisms underlying these problems have rarely been integrated in proposed models of spinal cord injury (SCI). Several parallels suggest significant overlap of these mechanisms, although the relationships between sympathetic function (dysregulated in AD) and nociceptive function (dysregulated in neuropathic pain) are complex. One general mechanism likely to be shared is central sensitization - enhanced responsiveness and synaptic reorganization of spinal circuits that mediate sympathetic reflexes or that process and relay pain-related information to the brain. Another is enhanced sensory input to spinal circuits caused by extensive alterations in primary sensory neurons. Both AD and SCI-induced neuropathic pain are associated with spinal sprouting of peptidergic nociceptors that might increase synaptic input to the circuits involved in AD and SCI pain. In addition, numerous nociceptors become hyperexcitable, hypersensitive to chemicals associated with injury and inflammation, and spontaneously active, greatly amplifying sensory input to sensitized spinal circuits. As discussed with the aid of a preliminary functional model, these effects are likely to have mutually reinforcing relationships with each other, and with consequences of SCI-induced interruption of descending excitatory and inhibitory influences on spinal circuits, with SCI-induced inflammation in the spinal cord and in DRGs, and with activity in sympathetic fibers within DRGs that promotes local inflammation and spontaneous activity in sensory neurons. This model suggests that interventions selectively targeting hyperactivity in C-nociceptors might be useful for treating chronic pain and AD after high SCI.
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Affiliation(s)
- Edgar T Walters
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA.
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Upregulation of the sodium channel NaVβ4 subunit and its contributions to mechanical hypersensitivity and neuronal hyperexcitability in a rat model of radicular pain induced by local dorsal root ganglion inflammation. Pain 2017; 157:879-891. [PMID: 26785322 DOI: 10.1097/j.pain.0000000000000453] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
High-frequency spontaneous firing in myelinated sensory neurons plays a key role in initiating pain behaviors in several different models, including the radicular pain model in which the rat lumbar dorsal root ganglia (DRG) are locally inflamed. The sodium channel isoform NaV1.6 contributes to pain behaviors and spontaneous activity in this model. Among all isoforms in adult DRG, NaV1.6 is the main carrier of tetrodotoxin-sensitive resurgent Na currents that allow high-frequency firing. Resurgent currents flow after a depolarization or action potential, as a blocking particle exits the pore. In most neurons, the regulatory β4 subunit is potentially the endogenous blocker. We used in vivo siRNA-mediated knockdown of NaVβ4 to examine its role in the DRG inflammation model. NaVβ4 but not control siRNA almost completely blocked mechanical hypersensitivity induced by DRG inflammation. Microelectrode recordings in isolated whole DRG showed that NaVβ4 siRNA blocked the inflammation-induced increase in spontaneous activity of Aβ neurons and reduced repetitive firing and other measures of excitability. NaVβ4 was preferentially expressed in larger diameter cells; DRG inflammation increased its expression, and this was reversed by NaVβ4 siRNA, based on immunohistochemistry and Western blotting. NaVβ4 siRNA also reduced immunohistochemical NaV1.6 expression. Patch-clamp recordings of tetrodotoxin-sensitive Na currents in acutely cultured medium diameter DRG neurons showed that DRG inflammation increased transient and especially resurgent current, effects blocked by NaVβ4 siRNA. NaVβ4 may represent a more specific target for pain conditions that depend on myelinated neurons expressing NaV1.6.
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43
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Barbosa C, Xiao Y, Johnson AJ, Xie W, Strong JA, Zhang JM, Cummins TR. FHF2 isoforms differentially regulate Nav1.6-mediated resurgent sodium currents in dorsal root ganglion neurons. Pflugers Arch 2016; 469:195-212. [PMID: 27999940 DOI: 10.1007/s00424-016-1911-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 10/19/2016] [Accepted: 11/20/2016] [Indexed: 10/20/2022]
Abstract
Nav1.6 and Nav1.6-mediated resurgent currents have been implicated in several pain pathologies. However, our knowledge of how fast resurgent currents are modulated in neurons is limited. Our study explored the potential regulation of Nav1.6-mediated resurgent currents by isoforms of fibroblast growth factor homologous factor 2 (FHF2) in an effort to address the gap in our knowledge. FHF2 isoforms colocalize with Nav1.6 in peripheral sensory neurons. Cell line studies suggest that these proteins differentially regulate inactivation. In particular, FHF2A mediates long-term inactivation, a mechanism proposed to compete with the open-channel blocker mechanism that mediates resurgent currents. On the other hand, FHF2B lacks the ability to mediate long-term inactivation and may delay inactivation favoring open-channel block. Based on these observations, we hypothesized that FHF2A limits resurgent currents, whereas FHF2B enhances resurgent currents. Overall, our results suggest that FHF2A negatively regulates fast resurgent current by enhancing long-term inactivation and delaying recovery. In contrast, FHF2B positively regulated resurgent current and did not alter long-term inactivation. Chimeric constructs of FHF2A and Navβ4 (likely the endogenous open channel blocker in sensory neurons) exhibited differential effects on resurgent currents, suggesting that specific regions within FHF2A and Navβ4 have important regulatory functions. Our data also indicate that FHFAs and FHF2B isoform expression are differentially regulated in a radicular pain model and that associated neuronal hyperexcitability is substantially attenuated by a FHFA peptide. As such, these findings suggest that FHF2A and FHF2B regulate resurgent current in sensory neurons and may contribute to hyperexcitability associated with some pain pathologies.
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Affiliation(s)
- Cindy Barbosa
- Department of Pharmacology and Toxicology, Indiana University, Indianapolis, IN, USA.,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Yucheng Xiao
- Department of Pharmacology and Toxicology, Indiana University, Indianapolis, IN, USA.,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Andrew J Johnson
- Department of Pharmacology and Toxicology, Indiana University, Indianapolis, IN, USA.,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Wenrui Xie
- Department of Anesthesiology, University of Cincinnati, Cincinnati, OH, USA
| | - Judith A Strong
- Department of Anesthesiology, University of Cincinnati, Cincinnati, OH, USA
| | - Jun-Ming Zhang
- Department of Anesthesiology, University of Cincinnati, Cincinnati, OH, USA
| | - Theodore R Cummins
- Department of Pharmacology and Toxicology, Indiana University, Indianapolis, IN, USA. .,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA. .,Department of Biology, Indiana University - Purdue University Indianapolis, Indianapolis, IN, USA.
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Presence of Spontaneous Pain and Comorbid Pain Conditions Identifies Vulvodynia Subgroups. J Low Genit Tract Dis 2016; 20:57-63. [PMID: 26704330 DOI: 10.1097/lgt.0000000000000166] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The aims of the study were to define the heterogeneity of vulvodynia by determining data-driven subgroups within the vulvodynia diagnosis using exploratory cluster analysis and to characterize the subgroups identified. MATERIALS AND METHODS Included were participants in the longitudinal population-based study of vulvodynia in southeast Michigan who screened positive for vulvodynia at least once during the study. A cluster analysis using variables reflecting vulvar pain characteristics and comorbid pain conditions was conducted. Variables reflecting best separation of clusters were used to assign participants to subgroup categories. Demographic, psychiatric, general health, and other vulvar pain characteristics were summarized for each subgroup, followed by multinomial regression and pairwise comparisons of subgroups on these factors. RESULTS Of 441 women screening positive for vulvodynia during the course of the study, 393 were eligible on the basis of data requirements. Cluster analysis suggested that best subgroup separation was based on the following 2 variables: (1) presence or absence of spontaneous vulvar pain and (2) presence or absence of other comorbid pain conditions. Subgroups did not differ by age or ethnicity. The subgroup having spontaneous pain and other comorbid conditions demonstrated greatest morbidity in general health measures, psychiatric disorders, and other vulvar pain measures. Primary versus secondary vulvodynia did not vary between subgroups and did not assist in subgroup separation in the cluster analysis. DISCUSSION Subgroups based on exploratory cluster analysis demonstrated that presence of spontaneous pain and the presence of comorbid pain conditions resulted in best separation of groups. Presence of both spontaneous pain and other comorbid pain conditions identified the group with greatest morbidity.
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Tanaka BS, Zhao P, Dib-Hajj FB, Morisset V, Tate S, Waxman SG, Dib-Hajj SD. A gain-of-function mutation in Nav1.6 in a case of trigeminal neuralgia. Mol Med 2016; 22:338-348. [PMID: 27496104 DOI: 10.2119/molmed.2016.00131] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 07/18/2016] [Indexed: 01/29/2023] Open
Abstract
Idiopathic trigeminal neuralgia (TN) is a debilitating pain disorder characterized by episodic unilateral facial pain along the territory of branches of the trigeminal nerve. Human painful disorders, but not TN, have been linked to gain-of-function mutations in peripheral voltage-gated sodium channels (NaV1.7, NaV1.8 and NaV1.9). Gain-of-function mutations in NaV1.6, which is expressed in myelinated and unmyelinated CNS and peripheral nervous system neurons and supports neuronal high-frequency firing, have been linked to epilepsy but not to pain. Here, we describe an individual who presented with evoked and spontaneous paroxysmal unilateral facial pain, and carried a diagnosis of TN. Magnetic resonance imaging showed unilateral neurovascular compression, consistent with pain in areas innervated by the second branch of the trigeminal nerve. Genetic analysis as part of a phase 2 clinical study in patients with TN conducted by Convergence Pharmaceuticals Ltd revealed a previously undescribed de novo missense mutation in NaV1.6 (c.A406G; p.Met136Val). Whole-cell voltage-clamp recordings show that the Met136Val mutation significantly increases peak current density (1.5-fold) and resurgent current (1.6-fold) without altering gating properties. Current-clamp studies in trigeminal ganglion (TRG) neurons showed that Met136Val increased the fraction of high-firing neurons, lowered the current threshold and increased the frequency of evoked action potentials in response to graded stimuli. Our results demonstrate a novel NaV1.6 mutation in TN, and show that this mutation potentiates transient and resurgent sodium currents and leads to increased excitability in TRG neurons. We suggest that this gain-of-function NaV1.6 mutation may exacerbate the pathophysiology of vascular compression and contribute to TN.
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Affiliation(s)
- Brian S Tanaka
- Department of Neurology.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT 06510.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT 06516
| | - Peng Zhao
- Department of Neurology.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT 06510.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT 06516
| | - Fadia B Dib-Hajj
- Department of Neurology.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT 06510.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT 06516
| | - Valerie Morisset
- Convergence Pharmaceuticals Ltd, a Biogen company, Cambridge, United Kingdom
| | - Simon Tate
- Convergence Pharmaceuticals Ltd, a Biogen company, Cambridge, United Kingdom
| | - Stephen G Waxman
- Department of Neurology.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT 06510.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT 06516
| | - Sulayman D Dib-Hajj
- Department of Neurology.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT 06510.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT 06516
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Ramachandra R, Elmslie KS. EXPRESS: Voltage-dependent sodium (NaV) channels in group IV sensory afferents. Mol Pain 2016; 12:12/0/1744806916660721. [PMID: 27385723 PMCID: PMC4956173 DOI: 10.1177/1744806916660721] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Patients with intermittent claudication suffer from both muscle pain and an exacerbated exercise pressor reflex. Excitability of the group III and group IV afferent fibers mediating these functions is controlled in part by voltage-dependent sodium (NaV) channels. We previously found tetrodotoxin-resistant NaV1.8 channels to be the primary type in muscle afferent somata. However, action potentials in group III and IV afferent axons are blocked by TTX, supporting a minimal role of NaV1.8 channels. To address these apparent differences in NaV channel expression between axon and soma, we used immunohistochemistry to identify the NaV channels expressed in group IV axons within the gastrocnemius muscle and the dorsal root ganglia sections. Positive labeling by an antibody against the neurofilament protein peripherin was used to identify group IV neurons and axons. We show that >67% of group IV fibers express NaV1.8, NaV1.6, or NaV1.7. Interestingly, expression of NaV1.8 channels in group IV somata was significantly higher than in the fibers, whereas there were no significant differences for either NaV1.6 or NaV1.7. When combined with previous work, our results suggest that NaV1.8 channels are expressed in most group IV axons, but that, under normal conditions, NaV1.6 and/or NaV1.7 play a more important role in action potential generation to signal muscle pain and the exercise pressor reflex.
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Affiliation(s)
- Renuka Ramachandra
- The Baker Laboratory of Pharmacology, Department of Pharmacology, AT Still University of Health Sciences, Kirksville, MO, USA
- Renuka Ramachandra, The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, AT Still University of Health Sciences, Kirksville, MO 63501, USA.
| | - Keith S Elmslie
- The Baker Laboratory of Pharmacology, Department of Pharmacology, AT Still University of Health Sciences, Kirksville, MO, USA
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Barbosa C, Cummins TR. Unusual Voltage-Gated Sodium Currents as Targets for Pain. CURRENT TOPICS IN MEMBRANES 2016; 78:599-638. [PMID: 27586296 DOI: 10.1016/bs.ctm.2015.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pain is a serious health problem that impacts the lives of many individuals. Hyperexcitability of peripheral sensory neurons contributes to both acute and chronic pain syndromes. Because voltage-gated sodium currents are crucial to the transmission of electrical signals in peripheral sensory neurons, the channels that underlie these currents are attractive targets for pain therapeutics. Sodium currents and channels in peripheral sensory neurons are complex. Multiple-channel isoforms contribute to the macroscopic currents in nociceptive sensory neurons. These different isoforms exhibit substantial variations in their kinetics and pharmacology. Furthermore, sodium current complexity is enhanced by an array of interacting proteins that can substantially modify the properties of voltage-gated sodium channels. Resurgent sodium currents, atypical currents that can enhance recovery from inactivation and neuronal firing, are increasingly being recognized as playing potentially important roles in sensory neuron hyperexcitability and pain sensations. Here we discuss unusual sodium channels and currents that have been identified in nociceptive sensory neurons, describe what is known about the molecular determinants of the complex sodium currents in these neurons. Finally, we provide an overview of therapeutic strategies to target voltage-gated sodium currents in nociceptive neurons.
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Affiliation(s)
- C Barbosa
- Indiana University School of Medicine, Indianapolis, IN, United States
| | - T R Cummins
- Indiana University School of Medicine, Indianapolis, IN, United States
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Sun L, Lutz BM, Tao YX. The CRISPR/Cas9 system for gene editing and its potential application in pain research. TRANSLATIONAL PERIOPERATIVE AND PAIN MEDICINE 2016; 1:22-33. [PMID: 27500183 PMCID: PMC4971521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The CRISPR/Cas9 system is a research hotspot in genome editing and regulation. Currently, it is used in genomic silencing and knock-in experiments as well as transcriptional activation and repression. This versatile system consists of two components: a guide RNA (gRNA) and a Cas9 nuclease. Recognition of a genomic DNA target is mediated through base pairing with a 20-base gRNA. The latter further recruits the Cas9 endonuclease protein to the target site and creates double-stranded breaks in the target DNA. Compared with traditional genome editing directed by DNA-binding protein domains, this short RNA-directed Cas9 endonuclease system is simple and easily programmable. Although this system may have off-target effects and in vivo delivery and immune challenges, researchers have employed this system in vivo to establish disease models, study specific gene functions under certain disease conditions, and correct genomic information for disease treatment. In regards to pain research, the CRISPR/Cas9 system may act as a novel tool in gene correction therapy for pain-associated hereditary diseases and may be a new approach for RNA-guided transcriptional activation or repression of pain-related genes. In addition, this system is also applied to loss-of-function mutations in pain-related genes and knockin of reporter genes or loxP tags at pain-related genomic loci. The CRISPR/Cas9 system will likely be carried out widely in both bench work and clinical settings in the pain field.
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Affiliation(s)
- Linlin Sun
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Brianna Marie Lutz
- Rutgers Graduate School of Biomedical Sciences, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Yuan-Xiang Tao
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
- Rutgers Graduate School of Biomedical Sciences, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
- Departments of Cell Biology & Molecular Medicine, Physiology, Pharmacology, & Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
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Rivara M, Zuliani V. Novel sodium channel antagonists in the treatment of neuropathic pain. Expert Opin Investig Drugs 2015; 25:215-26. [PMID: 26576738 DOI: 10.1517/13543784.2016.1121992] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Effective and safe drugs for the treatment of neuropathic pain are still an unmet clinical need. Neuropathic pain, caused by a lesion or disease that affects the somatosensory system, is a debilitating and hampering condition that has a great economic cost and, above all, a tremendous impact on the quality of life. Sodium channels are one of the major players in generating and propagating action potentials. They represent an appealing target for researchers involved in the development of new and safer drugs useful in the treatment of neuropathic pain. The actual goal for researchers is to target sodium channels selectively to stop the abnormal signaling that characterizes neuropathic pain while leaving normal somatosensory functions intact. AREAS COVERED This review covers the most recent publications regarding sodium channel blockers and their development as new treatments for neuropathic pain. The main areas discussed are the natural sources of new blockers, such as venom extracts and the recent efforts from many pharmaceutical companies in the field. EXPERT OPINION There have been serious efforts by both the pharmaceutical industry and academia to develop new and safer therapeutic options for neuropathic pain. A number of different strategies have been undertaken; the main efforts directed towards the identification of selective blockers starting from both natural products or screening chemical libraries. At this time, researchers have identified and characterized selective compounds against NaV1.7 or NaV1.8 voltage-gated sodium channels but only time will tell if they reach the market.
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Affiliation(s)
- Mirko Rivara
- a Dipartimento di Farmacia , Università degli Studi di Parma , Via Area delle Scienze 27/A, I-43124 Parma , Italy
| | - Valentina Zuliani
- a Dipartimento di Farmacia , Università degli Studi di Parma , Via Area delle Scienze 27/A, I-43124 Parma , Italy
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Bao L. Trafficking regulates the subcellular distribution of voltage-gated sodium channels in primary sensory neurons. Mol Pain 2015; 11:61. [PMID: 26423360 PMCID: PMC4590712 DOI: 10.1186/s12990-015-0065-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 09/23/2015] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (Navs) comprise at least nine pore-forming α subunits. Of these, Nav1.6, Nav1.7, Nav1.8 and Nav1.9 are the most frequently studied in primary sensory neurons located in the dorsal root ganglion and are mainly localized to the cytoplasm. A large pool of intracellular Navs raises the possibility that changes in Nav trafficking could alter channel function. The molecular mediators of Nav trafficking mainly consist of signals within the Navs themselves, interacting proteins and extracellular factors. The surface expression of Navs is achieved by escape from the endoplasmic reticulum and proteasome degradation, forward trafficking and plasma membrane anchoring, and it is also regulated by channel phosphorylation and ubiquitination in primary sensory neurons. Axonal transport and localization of Navs in afferent fibers involves the motor protein KIF5B and scaffold proteins, including contactin and PDZ domain containing 2. Localization of Nav1.6 to the nodes of Ranvier in myelinated fibers of primary sensory neurons requires node formation and the submembrane cytoskeletal protein complex. These findings inform our understanding of the molecular and cellular mechanisms underlying Nav trafficking in primary sensory neurons.
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Affiliation(s)
- Lan Bao
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, 200031, China.
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