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Cao B, Xu Q, Shi Y, Zhao R, Li H, Zheng J, Liu F, Wan Y, Wei B. Pathology of pain and its implications for therapeutic interventions. Signal Transduct Target Ther 2024; 9:155. [PMID: 38851750 PMCID: PMC11162504 DOI: 10.1038/s41392-024-01845-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 04/08/2024] [Accepted: 04/25/2024] [Indexed: 06/10/2024] Open
Abstract
Pain is estimated to affect more than 20% of the global population, imposing incalculable health and economic burdens. Effective pain management is crucial for individuals suffering from pain. However, the current methods for pain assessment and treatment fall short of clinical needs. Benefiting from advances in neuroscience and biotechnology, the neuronal circuits and molecular mechanisms critically involved in pain modulation have been elucidated. These research achievements have incited progress in identifying new diagnostic and therapeutic targets. In this review, we first introduce fundamental knowledge about pain, setting the stage for the subsequent contents. The review next delves into the molecular mechanisms underlying pain disorders, including gene mutation, epigenetic modification, posttranslational modification, inflammasome, signaling pathways and microbiota. To better present a comprehensive view of pain research, two prominent issues, sexual dimorphism and pain comorbidities, are discussed in detail based on current findings. The status quo of pain evaluation and manipulation is summarized. A series of improved and innovative pain management strategies, such as gene therapy, monoclonal antibody, brain-computer interface and microbial intervention, are making strides towards clinical application. We highlight existing limitations and future directions for enhancing the quality of preclinical and clinical research. Efforts to decipher the complexities of pain pathology will be instrumental in translating scientific discoveries into clinical practice, thereby improving pain management from bench to bedside.
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Affiliation(s)
- Bo Cao
- Department of General Surgery, First Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
| | - Qixuan Xu
- Department of General Surgery, First Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
- Medical School of Chinese PLA, Beijing, 100853, China
| | - Yajiao Shi
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, 100191, China
| | - Ruiyang Zhao
- Department of General Surgery, First Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
- Medical School of Chinese PLA, Beijing, 100853, China
| | - Hanghang Li
- Department of General Surgery, First Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
- Medical School of Chinese PLA, Beijing, 100853, China
| | - Jie Zheng
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, 100191, China
| | - Fengyu Liu
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, 100191, China.
| | - You Wan
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, 100191, China.
| | - Bo Wei
- Department of General Surgery, First Medical Center, Chinese PLA General Hospital, Beijing, 100853, China.
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Brackx W, de Cássia Collaço R, Theys M, Cruyssen JV, Bosmans F. Understanding the physiological role of Na V1.9: Challenges and opportunities for pain modulation. Pharmacol Ther 2023; 245:108416. [PMID: 37061202 DOI: 10.1016/j.pharmthera.2023.108416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/31/2023] [Accepted: 04/12/2023] [Indexed: 04/17/2023]
Abstract
Voltage-activated Na+ (NaV) channels are crucial contributors to rapid electrical signaling in the human body. As such, they are among the most targeted membrane proteins by clinical therapeutics and natural toxins. Several of the nine mammalian NaV channel subtypes play a documented role in pain or other sensory processes such as itch, touch, and smell. While causal relationships between these subtypes and biological function have been extensively described, the physiological role of NaV1.9 is less understood. Yet, mutations in NaV1.9 can cause striking disease phenotypes related to sensory perception such as loss or gain of pain and chronic itch. Here, we explore our current knowledge of the mechanisms by which NaV1.9 may contribute to pain and elaborate on the challenges associated with establishing links between experimental conditions and human disease. This review also discusses the lack of comprehensive insights into NaV1.9-specific pharmacology, an unfortunate situation since modulatory compounds may have tremendous potential in the clinic to treat pain or as precision tools to examine the extent of NaV1.9 participation in sensory perception processes.
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Affiliation(s)
- Wayra Brackx
- Molecular Physiology and Neurophysics Group, Department of Basic and Applied Medical Sciences, University of Ghent, Ghent, Belgium
| | - Rita de Cássia Collaço
- Molecular Physiology and Neurophysics Group, Department of Basic and Applied Medical Sciences, University of Ghent, Ghent, Belgium
| | - Margaux Theys
- Molecular Physiology and Neurophysics Group, Department of Basic and Applied Medical Sciences, University of Ghent, Ghent, Belgium
| | - Jolien Vander Cruyssen
- Molecular Physiology and Neurophysics Group, Department of Basic and Applied Medical Sciences, University of Ghent, Ghent, Belgium
| | - Frank Bosmans
- Molecular Physiology and Neurophysics Group, Department of Basic and Applied Medical Sciences, University of Ghent, Ghent, Belgium.
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Sukhanova KY, Koirala A, Elmslie KS. Na V1.9 current in muscle afferent neurons is enhanced by substances released during muscle activity. J Neurophysiol 2022; 128:739-750. [PMID: 36043704 PMCID: PMC9512110 DOI: 10.1152/jn.00116.2022] [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: 03/22/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 11/22/2022] Open
Abstract
Skeletal muscle contraction triggers the exercise pressor reflex (EPR) to regulate the cardiovascular system response to exercise. During muscle contraction, substances are released that generate action potential activity in group III and IV afferents that mediate the EPR. Some of these substances increase afferent activity via G-protein-coupled receptor (GPCR) activation, but the mechanisms are incompletely understood. We were interested in determining if tetrodotoxin-resistant (TTX-R) voltage-dependent sodium channels (NaV) were involved and investigated the effect of a mixture of such compounds (bradykinin, prostaglandin, norepinephrine, and ATP, called muscle metabolites). Using whole cell patch-clamp electrophysiology, we show that the muscle metabolites significantly increased TTX-R NaV currents. The rise time of this enhancement averaged ∼2 min, which suggests the involvement of a diffusible second messenger pathway. The effect of muscle metabolites on the current-voltage relationship, channel activation and inactivation kinetics support NaV1.9 channels as the target for this enhancement. When applied individually at the concentration used in the mixture, only prostaglandin and bradykinin significantly enhanced NaV current, but the sum of these enhancements was <1/3 that observed when the muscle metabolites were applied together. This suggests synergism between the activated GPCRs to enhance NaV1.9 current. When applied at a higher concentration, all four substances could enhance the current, which demonstrates that the GPCRs activated by each metabolite can enhance channel activity. The enhancement of NaV1.9 channel activity is a likely mechanism by which GPCR activation increases action potential activity in afferents generating the EPR.NEW & NOTEWORTHY G-protein-coupled receptor (GPCR) activation increases action potential activity in muscle afferents to produce the exercise pressor reflex (EPR), but the mechanisms are incompletely understood. We provide evidence that NaV1.9 current is synergistically enhanced by application of a mixture of metabolites potentially released during muscle contraction. The enhancement of NaV1.9 current is likely one mechanism by which GPCR activation generates the EPR and the inappropriate activation of the EPR in patients with cardiovascular disease.
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Affiliation(s)
- Khrystyna Yu Sukhanova
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
| | - Ankeeta Koirala
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
| | - Keith S Elmslie
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
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de Lima FO, Lauria PSS, do Espírito-Santo RF, Evangelista AF, Nogueira TMO, Araldi D, Soares MBP, Villarreal CF. Unveiling Targets for Treating Postoperative Pain: The Role of the TNF-α/p38 MAPK/NF-κB/Nav1.8 and Nav1.9 Pathways in the Mouse Model of Incisional Pain. Int J Mol Sci 2022; 23:ijms231911630. [PMID: 36232927 PMCID: PMC9570460 DOI: 10.3390/ijms231911630] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 09/18/2022] [Accepted: 09/27/2022] [Indexed: 11/16/2022] Open
Abstract
Although the mouse model of incisional pain is broadly used, the mechanisms underlying plantar incision-induced nociception are not fully understood. This work investigates the role of Nav1.8 and Nav1.9 sodium channels in nociceptive sensitization following plantar incision in mice and the signaling pathway modulating these channels. A surgical incision was made in the plantar hind paw of male Swiss mice. Nociceptive thresholds were assessed by von Frey filaments. Gene expression of Nav1.8, Nav1.9, TNF-α, and COX-2 was evaluated by Real-Time PCR in dorsal root ganglia (DRG). Knockdown mice for Nav1.8 and Nav1.9 were produced by antisense oligodeoxynucleotides intrathecal treatments. Local levels of TNF-α and PGE2 were immunoenzymatically determined. Incised mice exhibited hypernociception and upregulated expression of Nav1.8 and Nav1.9 in DRG. Antisense oligodeoxynucleotides reduced hypernociception and downregulated Nav1.8 and Nav1.9. TNF-α and COX-2/PGE2 were upregulated in DRG and plantar skin. Inhibition of TNF-α and COX-2 reduced hypernociception, but only TNF-α inhibition downregulated Nav1.8 and Nav1.9. Antagonizing NF-κB and p38 mitogen-activated protein kinase (MAPK), but not ERK or JNK, reduced both hypernociception and hyperexpression of Nav1.8 and Nav1.9. This study proposes the contribution of the TNF-α/p38/NF-κB/Nav1.8 and Nav1.9 pathways to the pathophysiology of the mouse model of incisional pain.
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Affiliation(s)
- Flávia Oliveira de Lima
- Health Department, State University of Feira de Santana, Feira de Santana 44036900, BA, Brazil
| | | | | | - Afrânio Ferreira Evangelista
- SENAI Institute of Innovation in Advanced Health Systems, University Center SENAI/CIMATEC, Salvador 41650010, BA, Brazil
| | | | - Dionéia Araldi
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, Campinas 13083-862, SP, Brazil
| | - Milena Botelho Pereira Soares
- Gonçalo Moniz Institute, Oswaldo Cruz Foundation, Salvador 40296710, BA, Brazil
- SENAI Institute of Innovation in Advanced Health Systems, University Center SENAI/CIMATEC, Salvador 41650010, BA, Brazil
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Goodwin G, McMurray S, Stevens EB, Denk F, McMahon SB. Examination of the contribution of Nav1.7 to axonal propagation in nociceptors. Pain 2022; 163:e869-e881. [PMID: 34561392 DOI: 10.1097/j.pain.0000000000002490] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 09/09/2021] [Indexed: 11/25/2022]
Abstract
ABSTRACT Nav1.7 is a promising drug target for the treatment of pain. However, there is a mismatch between the analgesia produced by Nav1.7 loss-of-function and the peripherally restricted Nav1.7 inhibitors, which may reflect a lack of understanding of the function of Nav1.7 in the transmission of nociceptive information. In the periphery, the role of Nav1.7 in transduction at nociceptive peripheral terminals has been comprehensively examined, but its role in axonal propagation in these neurons is less clearly defined. In this study, we examined the contribution of Nav1.7 to axonal propagation in nociceptors using sodium channel blockers in in vivo electrophysiological and calcium imaging recordings in mice. Using the sodium channel blocker tetrodotoxin (TTX) (1-10 µM) to inhibit Nav1.7 and other tetrodotoxin-sensitive sodium channels along the sciatic nerve, we first showed that around two-thirds of nociceptive L4 dorsal root ganglion neurons innervating the skin, but a lower proportion innervating the muscle (45%), are blocked by TTX. By contrast, nearly all large-sized cutaneous afferents (95%-100%) were blocked by axonal TTX. Many cutaneous nociceptors resistant to TTX were polymodal (57%) and capsaicin sensitive (57%). Next, we applied PF-05198007 (300 nM-1 µM) to the sciatic nerve between stimulating and recording sites to selectively block axonal Nav1.7 channels. One hundred to three hundred nanomolar PF-05198007 blocked propagation in 63% of C-fiber sensory neurons, whereas similar concentrations produced minimal block (5%) in rapidly conducting A-fiber neurons. We conclude that Nav1.7 is essential for axonal propagation in around two-thirds of nociceptive cutaneous C-fiber neurons and a lower proportion (≤45%) of nociceptive neurons innervating muscle.
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Affiliation(s)
- George Goodwin
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, United Kingdom
| | | | | | - Franziska Denk
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, United Kingdom
| | - Stephen B McMahon
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, King's College London, United Kingdom
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6
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Scorpion Neurotoxin Syb-prII-1 Exerts Analgesic Effect through Nav1.8 Channel and MAPKs Pathway. Int J Mol Sci 2022; 23:ijms23137065. [PMID: 35806068 PMCID: PMC9266357 DOI: 10.3390/ijms23137065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 06/19/2022] [Accepted: 06/21/2022] [Indexed: 02/06/2023] Open
Abstract
Trigeminal neuralgia (TN) is a common type of peripheral neuralgia in clinical practice, which is usually difficult to cure. Common analgesic drugs are difficult for achieving the desired analgesic effect. Syb-prII-1 is a β-type scorpion neurotoxin isolated from the scorpion venom of Buthus martensi Karsch (BmK). It has an important influence on the voltage-gated sodium channel (VGSCs), especially closely related to Nav1.8 and Nav1.9. To explore whether Syb-prII-1 has a good analgesic effect on TN, we established the Sprague Dawley (SD) rats’ chronic constriction injury of the infraorbital nerve (IoN-CCI) model. Behavioral, electrophysiological, Western blot, and other methods were used to verify the model. It was found that Syb-prII-1 could significantly relieve the pain behavior of IoN-CCI rats. After Syb-prII-1 was given, the phosphorylation level of the mitogen-activated protein kinases (MAPKs) pathway showed a dose-dependent decrease after IoN-CCI injury. Moreover, Syb-prII-1(4.0 mg/kg) could significantly change the steady-state activation and inactivation curves of Nav1.8. The steady-state activation and inactivation curves of Nav1.9 were similar to those of Nav1.8, but there was no significant difference. It was speculated that it might play an auxiliary role. The binding mode, critical residues, and specific interaction type of Syb-prII-1 and VSD2rNav1.8 were clarified with computational simulation methods. Our results indicated that Syb-prII-1 could provide a potential treatment for TN by acting on the Nav1.8 target.
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7
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Reeh PW, Fischer MJM. Nobel somatosensations and pain. Pflugers Arch 2022; 474:405-420. [PMID: 35157132 PMCID: PMC8924131 DOI: 10.1007/s00424-022-02667-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/17/2022] [Accepted: 01/18/2022] [Indexed: 12/12/2022]
Abstract
The Nobel prices 2021 for Physiology and Medicine have been awarded to David Julius and Ardem Patapoutian "for their discoveries of receptors for temperature and touch", TRPV1 and PIEZO1/2. The present review tells the past history of the capsaicin receptor, covers further selected TRP channels, TRPA1 in particular, and deals with mechanosensitivity in general and mechanical hyperalgesia in particular. Other achievements of the laureates and translational aspects of their work are shortly treated.
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Hoffmann T, Kistner K, Joksimovic SLJ, Todorovic SM, Reeh PW, Sauer SK. Painful diabetic neuropathy leads to functional Ca V3.2 expression and spontaneous activity in skin nociceptors of mice. Exp Neurol 2021; 346:113838. [PMID: 34450183 PMCID: PMC8549116 DOI: 10.1016/j.expneurol.2021.113838] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 07/15/2021] [Accepted: 08/07/2021] [Indexed: 12/26/2022]
Abstract
Painful diabetic neuropathy occurs in approximately 20% of diabetic patients with underlying pathomechanisms not fully understood. We evaluated the contribution of the CaV3.2 isoform of T-type calcium channel to hyperglycemia-induced changes in cutaneous sensory C-fiber functions and neuropeptide release employing the streptozotocin (STZ) diabetes model in congenic mouse strains including global knockouts (KOs). Hyperglycemia established for 3-5 weeks in male C57BL/6J mice led to major reorganizations in peripheral C-fiber functions. Unbiased electrophysiological screening of mechanosensitive single-fibers in isolated hairy hindpaw skin revealed a relative loss of (polymodal) heat sensing in favor of cold sensing. In healthy CaV3.2 KO mice both heat and cold sensitivity among the C-fibers seemed underrepresented in favor of exclusive mechanosensitivity, low-threshold in particular, which deficit became significant in the diabetic KOs. Diabetes also led to a marked increase in the incidence of spontaneous discharge activity among the C-fibers of wildtype mice, which was reduced by the specific CaV3.2 blocker TTA-P2 and largely absent in the KOs. Evaluation restricted to the peptidergic class of nerve fibers - measuring KCl-stimulated CGRP release - revealed a marked reduction in the sciatic nerve by TTA-P2 in healthy but not diabetic wildtypes, the latter showing CGRP release that was as much reduced as in healthy and, to the same extent, in diabetic CaV3.2 KOs. These data suggest that diabetes abrogates all CaV3.2 functionality in the peripheral nerve axons. In striking contrast, diabetes markedly increased the KCl-stimulated CGRP release from isolated hairy skin of wildtypes but not KO mice, and TTA-P2 reversed this increase, strongly suggesting a de novo expression of CaV3.2 in peptidergic cutaneous nerve endings which may contribute to the enhanced spontaneous activity. De-glycosylation by neuraminidase showed clear desensitizing effects, both in regard to spontaneous activity and stimulated CGRP release, but included actions independent of CaV3.2. However, as diabetes-enhanced glycosylation is decisive for intra-axonal trafficking, it may account for the substantial reorganizations of the CaV3.2 distribution. The results may strengthen the validation of CaV3.2 channel as a therapeutic target of treating painful diabetic neuropathy.
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Affiliation(s)
- Tal Hoffmann
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Universitaetsstrasse 17, 91054 Erlangen, Germany
| | - Katrin Kistner
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Universitaetsstrasse 17, 91054 Erlangen, Germany
| | - Sonja L J Joksimovic
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Slobodan M Todorovic
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Peter W Reeh
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Universitaetsstrasse 17, 91054 Erlangen, Germany
| | - Susanne K Sauer
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Universitaetsstrasse 17, 91054 Erlangen, Germany.
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Sotelo-Hitschfeld P, Bernal L, Zimmermann K. Odontoblasts are cold sensory cells in teeth: Comment on: L. Bernal, P. Sotelo-Hitschfeld, C. König, V. Sinica, A. Wyatt, Z. Winter, A. Hein, F. Touska, S. Reinhardt, A. Tragl, R. Kusuda, P. Wartenberg, A. Sclaroff, J. D. Pfeifer, F. Ectors, A. Dahl, M. Freichel, V. Vlachova, S. Brauchi, C. Roza, U. Boehm, D. E. Clapham, J. K. Lennerz, K. Zimmermann, Odontoblast TRPC5 channels signal cold pain in teeth. Sci. Adv. 7, eabf5567 (2021). Temperature (Austin) 2021; 10:9-12. [PMID: 37187828 PMCID: PMC10177670 DOI: 10.1080/23328940.2021.1933365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/18/2021] [Accepted: 05/18/2021] [Indexed: 10/20/2022] Open
Affiliation(s)
- Pamela Sotelo-Hitschfeld
- Department of Anesthesiology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg (FAU), Erlangen, Germany
- Institute of Physiology, Faculty of Medicine & Center for Interdisciplinary Studies on the Nervous System (Cisne), Universidad Austral De Chile, Valdivia, Chile
| | - Laura Bernal
- Department of Anesthesiology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg (FAU), Erlangen, Germany
- Departamento De Biología De Sistemas, Facultad De Medicina, Universidad De Alcalá, Alcalá De Henares, Spain
| | - Katharina Zimmermann
- Department of Anesthesiology, Erlangen University Hospital, Friedrich Alexander University of Erlangen-Nuremberg (FAU), Erlangen, Germany
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10
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Goodwin G, McMahon SB. The physiological function of different voltage-gated sodium channels in pain. Nat Rev Neurosci 2021; 22:263-274. [PMID: 33782571 DOI: 10.1038/s41583-021-00444-w] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2021] [Indexed: 02/01/2023]
Abstract
Evidence from human genetic pain disorders shows that voltage-gated sodium channel α-subtypes Nav1.7, Nav1.8 and Nav1.9 are important in the peripheral signalling of pain. Nav1.7 is of particular interest because individuals with Nav1.7 loss-of-function mutations are congenitally insensitive to acute and chronic pain, and there is considerable hope that phenocopying these effects with a pharmacological antagonist will produce a new class of analgesic drug. However, studies in these rare individuals do not reveal how and where voltage-gated sodium channels contribute to pain signalling, which is of critical importance for drug development. More than a decade of research utilizing rodent genetic models and pharmacological tools to study voltage-gated sodium channels in pain has begun to unravel the role of different subtypes. Here, we review the contribution of individual channel subtypes in three key physiological processes necessary for transmission of sensory information to the CNS: transduction of stimuli at peripheral nerve terminals, axonal transmission of action potentials and neurotransmitter release from central terminals. These data suggest that drugs seeking to recapitulate the analgesic effects of loss of function of Nav1.7 will need to be brain-penetrant - which most of those developed to date are not.
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Affiliation(s)
- George Goodwin
- Pain and Neurorestoration Group, King's College London, London, UK.
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11
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Haverinen J, Dzhumaniiazova I, Abramochkin DV, Hassinen M, Vornanen M. Effects of Na+ channel isoforms and cellular environment on temperature tolerance of cardiac Na+ current in zebrafish (Danio rerio) and rainbow trout (Oncorhynchus mykiss). J Exp Biol 2021; 224:237812. [PMID: 33914031 DOI: 10.1242/jeb.241067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 03/01/2021] [Indexed: 11/20/2022]
Abstract
Heat tolerance of heart rate in fish is suggested to be limited by impaired electrical excitation of the ventricle due to the antagonistic effects of high temperature on Na+ (INa) and K+ (IK1) ion currents (INa is depressed at high temperatures while IK1 is resistant to them). To examine the role of Na+ channel proteins in heat tolerance of INa, we compared temperature dependencies of zebrafish (Danio rerio, warm-dwelling subtropical species) and rainbow trout (Oncorhynchus mykiss, cold-active temperate species) ventricular INa, and INa generated by the cloned zebrafish and rainbow trout NaV1.4 and NaV1.5 Na+ channels in human embryonic kidney (HEK) cells. Whole-cell patch-clamp recordings showed that zebrafish ventricular INa has better heat tolerance and slower inactivation kinetics than rainbow trout ventricular INa. In contrast, heat tolerance and inactivation kinetics of zebrafish and rainbow trout NaV1.4 channels are similar when expressed in the identical cellular environment of HEK cells. The same applies to NaV1.5 channels. These findings indicate that thermal adaptation of ventricular INa is largely achieved by differential expression of Na+ channel alpha subunits: zebrafish that tolerate higher temperatures mainly express the slower NaV1.5 isoform, while rainbow trout that prefer cold waters mainly express the faster NaV1.4 isoform. Differences in elasticity (stiffness) of the lipid bilayer and/or accessory protein subunits of the channel assembly may also be involved in thermal adaptation of INa. The results are consistent with the hypothesis that slow Na+ channel kinetics are associated with increased heat tolerance of cardiac excitation.
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Affiliation(s)
- Jaakko Haverinen
- Department of Environmental and Biological Sciences, University of Eastern Finland, 80101 Joensuu, Finland
| | - Irina Dzhumaniiazova
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye Gory 1-12, 119234 Moscow, Russia
| | - Denis V Abramochkin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye Gory 1-12, 119234 Moscow, Russia.,Laboratory of Cardiac Electrophysiology, National Medical Research Center for Cardiology, 3rd Cherepkovskaya 15a, 121552 Moscow, Russia.,Department of Physiology, Pirogov Russian National Research Medical University, Ostrovityanova Str. 1, 117997 Moscow, Russia
| | - Minna Hassinen
- Department of Environmental and Biological Sciences, University of Eastern Finland, 80101 Joensuu, Finland
| | - Matti Vornanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, 80101 Joensuu, Finland
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12
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Vornanen M. Feeling the heat: source–sink mismatch as a mechanism underlying the failure of thermal tolerance. J Exp Biol 2020; 223:223/16/jeb225680. [DOI: 10.1242/jeb.225680] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
ABSTRACT
A mechanistic explanation for the tolerance limits of animals at high temperatures is still missing, but one potential target for thermal failure is the electrical signaling off cells and tissues. With this in mind, here I review the effects of high temperature on the electrical excitability of heart, muscle and nerves, and refine a hypothesis regarding high temperature-induced failure of electrical excitation and signal transfer [the temperature-dependent deterioration of electrical excitability (TDEE) hypothesis]. A central tenet of the hypothesis is temperature-dependent mismatch between the depolarizing ion current (i.e. source) of the signaling cell and the repolarizing ion current (i.e. sink) of the receiving cell, which prevents the generation of action potentials (APs) in the latter. A source–sink mismatch can develop in heart, muscles and nerves at high temperatures owing to opposite effects of temperature on source and sink currents. AP propagation is more likely to fail at the sites of structural discontinuities, including electrically coupled cells, synapses and branching points of nerves and muscle, which impose an increased demand of inward current. At these sites, temperature-induced source–sink mismatch can reduce AP frequency, resulting in low-pass filtering or a complete block of signal transmission. In principle, this hypothesis can explain a number of heat-induced effects, including reduced heart rate, reduced synaptic transmission between neurons and reduced impulse transfer from neurons to muscles. The hypothesis is equally valid for ectothermic and endothermic animals, and for both aquatic and terrestrial species. Importantly, the hypothesis is strictly mechanistic and lends itself to experimental falsification.
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Affiliation(s)
- Matti Vornanen
- Department of Environmental and Biological Sciences , University of Eastern Finland, 80101 Joensuu, Finland
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