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Sohns K, Kostenko A, Behrendt M, Schmelz M, Rukwied R, Carr R. Depolarization of mouse DRG neurons by GABA does not translate into acute pain or hyperalgesia in healthy human volunteers. PLoS One 2024; 19:e0307668. [PMID: 39186592 PMCID: PMC11346724 DOI: 10.1371/journal.pone.0307668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 07/09/2024] [Indexed: 08/28/2024] Open
Abstract
The majority of somatosensory DRG neurons express GABAA receptors (GABAAR) and depolarise in response to its activation based on the high intracellular chloride concentration maintained by the Na-K-Cl cotransporter type 1 (NKCC1). The translation of this response to peripheral nerve terminals in people is so far unclear. We show here that GABA (EC50 = 16.67μM) acting via GABAAR produces an influx of extracellular calcium in approximately 20% (336/1720) of isolated mouse DRG neurons. In contrast, upon injection into forearm skin of healthy volunteers GABA (1mM, 100μl) did not induce any overt sensations nor a specific flare response and did not sensitize C-nociceptors to slow depolarizing electrical sinusoidal stimuli. Block of the inward chloride transporter NKCC1 by furosemide (1mg/100μl) did not reduce electrically evoked pain ratings nor did repetitive GABA stimulation in combination with an inhibited NKCC1 driven chloride replenishment by furosemide. Finally, we generated a sustained period of C-fiber firing by iontophoretically delivering codeine or histamine to induce tonic itch. Neither the intensity nor the duration of histamine or codeine itch was affected by prior injection of furosemide. We conclude that although GABA can evoke calcium transients in a proportion of isolated mouse DRG neurons, it does not induce or modify pain or itch ratings in healthy human skin even when chloride gradients are altered by inhibition of the sodium coupled NKCC1 transporter.
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Affiliation(s)
- Kyra Sohns
- Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Anna Kostenko
- Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Marc Behrendt
- Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Martin Schmelz
- Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Roman Rukwied
- Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Richard Carr
- Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
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Anand S, Rajagopal S. A Comprehensive Review on the Regulatory Action of TRP Channels: A Potential Therapeutic Target for Nociceptive Pain. Neurosci Insights 2023; 18:26331055231220340. [PMID: 38146332 PMCID: PMC10749524 DOI: 10.1177/26331055231220340] [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] [Received: 08/04/2023] [Accepted: 11/28/2023] [Indexed: 12/27/2023] Open
Abstract
The transient receptor potential (TRP) superfamily of ion channels in humans comprises voltage-gated, non-selective cation channels expressed both in excitable as well as non-excitable cells. Four TRP channel subunits associate to create functional homo- or heterotetramers that allow the influx of calcium, sodium, and/or potassium. These channels are highly abundant in the brain and kidney and are important mediators of diverse biological functions including thermosensation, vascular tone, flow sensing in the kidney and irritant stimuli sensing. Inherited or acquired dysfunction of TRP channels influences cellular functions and signaling pathways resulting in multifaceted disorders affecting skeletal, renal, cardiovascular, and nervous systems. Studies have demonstrated the involvement of these channels in the generation and transduction of pain. Based on the multifaceted role orchestrated by these TRP channels, modulation of the activity of these channels presents an important strategy to influence cellular function by regulating intracellular calcium levels as well as membrane excitability. Therefore, there has been a remarkable pharmaceutical inclination toward TRP channels as therapeutic interventions. Several candidate drugs influencing the activity of these channels are already in the clinical trials pipeline. The present review encompasses the current understanding of TRP channels and TRP modulators in pain and pain management.
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Affiliation(s)
- Santosh Anand
- Department of Biotechnology, School of Applied Sciences, REVA University, Bengaluru, Karnataka, India
| | - Senthilkumar Rajagopal
- Department of Biotechnology, School of Applied Sciences, REVA University, Bengaluru, Karnataka, India
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Malci A, Lin X, Sandoval R, Gundelfinger ED, Naumann M, Seidenbecher CI, Herrera-Molina R. Ca 2+ signaling in postsynaptic neurons: Neuroplastin-65 regulates the interplay between plasma membrane Ca 2+ ATPases and ionotropic glutamate receptors. Cell Calcium 2022; 106:102623. [PMID: 35853264 DOI: 10.1016/j.ceca.2022.102623] [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: 01/30/2022] [Revised: 06/28/2022] [Accepted: 07/05/2022] [Indexed: 11/17/2022]
Abstract
Upon postsynaptic glutamate receptor activation, the cytosolic Ca2+ concentration rises and initiates signaling and plasticity in spines. The plasma membrane Ca2+ ATPase (PMCA) is a major player to limit the duration of cytosolic Ca2+ signals. It forms complexes with the glycoprotein neuroplastin (Np) isoforms Np55 and Np65 and functionally interplays with N-methyl-D-aspartate (NMDA)-type ionotropic glutamate receptors (iGluNRs). Moreover, binding of the Np65-specific extracellular domain to Ca2+-permeable GluA1-containing α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type ionotropic glutamate receptors (iGluA1Rs) was found to be required for long-term potentiation (LTP). However, the link between PMCA and iGluRs function to regulate cytosolic Ca2+ signals remained unclear. Here, we report that Np65 coordinates PMCA and iGluRs' functions to modulate the duration and amplitude of cytosolic Ca2+ transients in dendrites and spines of hippocampal neurons. Using live-cell Ca2+ imaging, acute pharmacological treatments, and GCaMP5G-expressing hippocampal neurons, we discovered that endogenous or Np65-promoted PMCA activity contributes to the restoration of basal Ca2+ levels and that this effect is dependent on iGluR activation. Super-resolution STED and confocal microscopy revealed that electrical stimulation increases the abundance of synaptic neuroplastin-PMCA complexes depending on iGluR activation and that low-rate overexpression of Np65 doubled PMCA levels and decreased cell surface levels of GluN2A and GluA1 in dendrites and Shank2-positive glutamatergic synapses. In neuroplastin-deficient hippocampi, we observed reduced PMCA and unchanged GluN2B levels, while GluN2A and GluA1 levels were imbalanced. Our electrophysiological data from hippocampal slices argues for an essential interplay of PMCA with GluN2A- but not with GluN2B-containing receptors upon induction of synaptic plasticity. Accordingly, we conclude that Np65 may interconnect PMCA with core players of glutamatergic neurotransmission to fine-tune the Ca2+ signal regulation in basal synaptic function and plasticity.
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Affiliation(s)
- Ayse Malci
- Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Xiao Lin
- Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Rodrigo Sandoval
- Departamento de Ciencias Biomédicas, Facultad de Medicina, Universidad Católica del Norte, Coquimbo, Chile
| | - Eckart D Gundelfinger
- Leibniz Institute for Neurobiology, Magdeburg, Germany; Center for Behavioral Brain Sciences, Magdeburg, Germany; Institute of Pharmacology and Toxicology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
| | - Michael Naumann
- Institute of Experimental Internal Medicine, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
| | - Constanze I Seidenbecher
- Leibniz Institute for Neurobiology, Magdeburg, Germany; Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Rodrigo Herrera-Molina
- Center for Behavioral Brain Sciences, Magdeburg, Germany; Centro Integrativo de Biología y Química Aplicada, Universidad Bernardo O'Higgins, Santiago, Chile; Combinatorial Combinatorial NeuroImaging (CNI), Leibniz Institute for Neurobiology, Magdeburg, Germany.
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Multitarget nociceptor sensitization by a promiscuous peptide from the venom of the King Baboon spider. Proc Natl Acad Sci U S A 2022; 119:2110932119. [PMID: 35074873 PMCID: PMC8812547 DOI: 10.1073/pnas.2110932119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2021] [Indexed: 12/15/2022] Open
Abstract
The King Baboon spider, Pelinobius muticus, is a burrowing African tarantula. Its impressive size and appealing coloration are tempered by reports describing severe localized pain, swelling, itchiness, and muscle cramping after accidental envenomation. Hyperalgesia is the most prominent symptom after bites from P. muticus, but the molecular basis by which the venom induces pain is unknown. Proteotranscriptomic analysis of P. muticus venom uncovered a cysteine-rich peptide, δ/κ-theraphotoxin-Pm1a (δ/κ-TRTX-Pm1a), that elicited nocifensive behavior when injected into mice. In small dorsal root ganglion neurons, synthetic δ/κ-TRTX-Pm1a (sPm1a) induced hyperexcitability by enhancing tetrodotoxin-resistant sodium currents, impairing repolarization and lowering the threshold of action potential firing, consistent with the severe pain associated with envenomation. The molecular mechanism of nociceptor sensitization by sPm1a involves multimodal actions over several ion channel targets, including NaV1.8, KV2.1, and tetrodotoxin-sensitive NaV channels. The promiscuous targeting of peptides like δ/κ-TRTX-Pm1a may be an evolutionary adaptation in pain-inducing defensive venoms.
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Velichkova AN, Coleman SE, Torsney C. Postoperative pain facilitates rat C-fibre activity-dependent slowing and induces thermal hypersensitivity in a sex-dependent manner. Br J Anaesth 2022; 128:718-733. [DOI: 10.1016/j.bja.2021.10.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 10/05/2021] [Accepted: 10/26/2021] [Indexed: 11/02/2022] Open
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Werland F, de Col R, Hirth M, Turnquist B, Schmelz M, Obreja O. Mechanical sensitization, increased axonal excitability, and spontaneous activity in C-nociceptors after ultraviolet B irradiation in pig skin. Pain 2021; 162:2002-2013. [PMID: 33449511 DOI: 10.1097/j.pain.0000000000002197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 12/30/2020] [Indexed: 11/26/2022]
Abstract
ABSTRACT Ultraviolet B (UVB) irradiation induces hyperalgesia in human and animal pain models. We investigated mechanical sensitization, increase in axonal excitability, and spontaneous activity in different C-nociceptor classes after UVB in pig skin. We focused on units with receptive fields covering both irradiated and nonirradiated skin allowing intraindividual comparisons. Thirty-five pigs were irradiated in a chessboard pattern, and extracellular single-fibre recordings were obtained 10 to 28 hours later (152 fibers). Units from the contralateral hind limb served as a control (n = 112). Irradiated and nonirradiated parts of the same innervation territory were compared in 36 neurons; low threshold C-touch fibers (n = 10) and sympathetic efferents (n = 2) were unchanged, but lower mechanical thresholds and higher discharge frequency at threshold were found in mechanosensitive nociceptors (n = 12). Half of them could be activated with nonnoxious brush stimuli in the sunburn. Four of 12 mechanoinsensitive nociceptors were found sensitized to mechanical stimulation in the irradiated part of the receptive field. Activity-dependent slowing of conduction was reduced in the irradiated and in the nonirradiated skin as compared with the control leg, whereas increased ability to follow high stimulation frequencies was restricted to the sunburn (108.5 ± 37 Hz UVB vs 6.3 ± 1 Hz control). Spontaneous activity was more frequent in the sunburn (72/152 vs 31/112). Mechanical sensitization of primary nociceptors and higher maximum after frequency are suggested to contribute to primary hyperalgesia, whereas the spontaneous activity of silent nociceptors might offer a mechanistic link contributing to ongoing pain and facilitated induction of spinal sensitization.
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Affiliation(s)
- Fiona Werland
- Department of Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Roberto de Col
- Department of Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Michael Hirth
- Department of Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Brian Turnquist
- Department of Mathematics and Computer Science, Bethel University, Saint Paul, MI, United States . Dr. Obreja is now with the Klinik für Rheumatologie und Schmerzmedizin, Bethesda Spital Basel, Basel, Switzerland
| | - Martin Schmelz
- Department of Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Otilia Obreja
- Department of Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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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: 62] [Impact Index Per Article: 20.7] [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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