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Gou R, Liu Y, Gou L, Mi S, Li X, Yang Y, Cheng X, Zhang Y. Transient Receptor Potential Channels in Sensory Mechanisms of the Lower Urinary Tract. Urol Int 2024:1-13. [PMID: 38657590 DOI: 10.1159/000538855] [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: 10/10/2023] [Accepted: 04/03/2024] [Indexed: 04/26/2024]
Abstract
BACKGROUND Urine storage and excretion require a network of interactions in the urinary tract and the central nervous system, which is mediated by a reservoir of water in the bladder and the outlet to the bladder neck, urethra, and external urethral sphincter. Through communicating and coordinating each other, micturition system eventually showed a switch-like activity pattern. SUMMARY At cervicothoracic and lumbosacral spine, the spinal reflex pathway of the lower urinary tract (LUT) received mechanosensory input from the urothelium to regulate the bladder contraction activity, thereby controlled urination voluntarily. Impairment of above-mentioned any level could result in lower urinary tract dysfunction, placed a huge burden on patients and society. Specific expression of purinergic receptors and transient receptor potential (TRP) channels are thought to play an important role in urinary excretion in the LUT. KEY MESSAGES This article reviewed the knowledge about the voiding reflex and described the role and function of TRP channels during voiding.
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Affiliation(s)
- Ruiqiang Gou
- The First Clinical Medical College, Lanzhou University, Lanzhou, China,
| | - Yuanyuan Liu
- The First Clinical Medical College, Lanzhou University, Lanzhou, China
| | - Li Gou
- The First Clinical Medical College, Lanzhou University, Lanzhou, China
| | - Shengyan Mi
- The First Clinical Medical College, Lanzhou University, Lanzhou, China
| | - Xiaonan Li
- The First Clinical Medical College, Lanzhou University, Lanzhou, China
| | - Yichen Yang
- The First Clinical Medical College, Lanzhou University, Lanzhou, China
| | - Xiaorong Cheng
- The Second Hospital and Clinical Medical School, Lanzhou University, Lanzhou, China
| | - Yibao Zhang
- The Second Hospital and Clinical Medical School, Lanzhou University, Lanzhou, China
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2
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Rohacs T. Phosphoinositide Regulation of TRP Channels: A Functional Overview in the Structural Era. Annu Rev Physiol 2024; 86:329-355. [PMID: 37871124 DOI: 10.1146/annurev-physiol-042022-013956] [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] [Indexed: 10/25/2023]
Abstract
Transient receptor potential (TRP) ion channels have diverse activation mechanisms including physical stimuli, such as high or low temperatures, and a variety of intracellular signaling molecules. Regulation by phosphoinositides and their derivatives is their only known common regulatory feature. For most TRP channels, phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] serves as a cofactor required for activity. Such dependence on PI(4,5)P2 has been demonstrated for members of the TRPM subfamily and for the epithelial TRPV5 and TRPV6 channels. Intracellular TRPML channels show specific activation by PI(3,5)P2. Structural studies uncovered the PI(4,5)P2 and PI(3,5)P2 binding sites for these channels and shed light on the mechanism of channel opening. PI(4,5)P2 regulation of TRPV1-4 as well as some TRPC channels is more complex, involving both positive and negative effects. This review discusses the functional roles of phosphoinositides in TRP channel regulation and molecular insights gained from recent cryo-electron microscopy structures.
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Affiliation(s)
- Tibor Rohacs
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey;
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3
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Ko J, Kim J, Myeong J, Kwak M, So I. Negative self-regulation of transient receptor potential canonical 4 by the specific interaction with phospholipase C-δ1. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2023; 27:187-196. [PMID: 36815258 PMCID: PMC9968946 DOI: 10.4196/kjpp.2023.27.2.187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 12/27/2022] [Accepted: 12/29/2022] [Indexed: 02/24/2023]
Abstract
Transient receptor potential canonical (TRPC) channels are non-selective calcium-permeable cation channels. It is suggested that TRPC4β is regulated by phospholipase C (PLC) signaling and is especially maintained by phosphatidylinositol 4,5-bisphosphate (PIP2). In this study, we present the regulation mechanism of the TRPC4 channel with PIP2 hydrolysis which is mediated by a channel-bound PLCδ1 but not by the GqPCR signaling pathway. Our electrophysiological recordings demonstrate that the Ca2+ via an open TRPC4 channel activates PLCδ1 in the physiological range, and it causes the decrease of current amplitude. The existence of PLCδ1 accelerated PIP2 depletion when the channel was activated by an agonist. Interestingly, PLCδ1 mutants which have lost the ability to regulate PIP2 level failed to reduce the TRPC4 current amplitude. Our results demonstrate that TRPC4 self-regulates its activity by allowing Ca2+ ions into the cell and promoting the PIP2 hydrolyzing activity of PLCδ1.
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Affiliation(s)
- Juyeon Ko
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Jinhyeong Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Jongyun Myeong
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Misun Kwak
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Insuk So
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea,Correspondence Insuk So, E-mail:
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4
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Hernández-Ortego P, Torres-Montero R, de la Peña E, Viana F, Fernández-Trillo J. Validation of Six Commercial Antibodies for the Detection of Heterologous and Endogenous TRPM8 Ion Channel Expression. Int J Mol Sci 2022; 23:ijms232416164. [PMID: 36555804 PMCID: PMC9784522 DOI: 10.3390/ijms232416164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022] Open
Abstract
TRPM8 is a non-selective cation channel expressed in primary sensory neurons and other tissues, including the prostate and urothelium. Its participation in different physiological and pathological processes such as thermoregulation, pain, itch, inflammation and cancer has been widely described, making it a promising target for therapeutic approaches. The detection and quantification of TRPM8 seems crucial for advancing the knowledge of the mechanisms underlying its role in these pathophysiological conditions. Antibody-based techniques are commonly used for protein detection and quantification, although their performance with many ion channels, including TRPM8, is suboptimal. Thus, the search for reliable antibodies is of utmost importance. In this study, we characterized the performance of six TRPM8 commercial antibodies in three immunodetection techniques: Western blot, immunocytochemistry and immunohistochemistry. Different outcomes were obtained for the tested antibodies; two of them proved to be successful in detecting TRPM8 in the three approaches while, in the conditions tested, the other four were acceptable only for specific techniques. Considering our results, we offer some insight into the usefulness of these antibodies for the detection of TRPM8 depending on the methodology of choice.
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Wei C, Kim B, McKemy DD. Transient receptor potential melastatin 8 is required for nitroglycerin- and calcitonin gene-related peptide-induced migraine-like pain behaviors in mice. Pain 2022; 163:2380-2389. [PMID: 35353773 PMCID: PMC9519811 DOI: 10.1097/j.pain.0000000000002635] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 03/10/2022] [Indexed: 11/25/2022]
Abstract
ABSTRACT Migraine is a complex neurovascular disorder that is one of the leading causes of disability and a reduced quality of life. Even with such a high societal impact, our understanding of the cellular and molecular mechanisms that contribute to migraine headaches is limited. To address this complex disorder, several groups have performed genome-wide association studies to elucidate migraine susceptibility genes, with many identifying transient receptor potential melastatin 8 (TRPM8), a cold-sensitive cation channel expressed in peripheral afferents innervating the trigeminovascular system, and the principal mediator of cold and cold pain associated with injury and disease. Interestingly, these migraine-associated single-nucleotide polymorphisms reside in noncoding regions of TRPM8, with those correlated with reduced migraine risk exhibiting lower TRPM8 expression and decreased cold sensitivity. Nonetheless, as a role for TRPM8 in migraine has yet to be defined, we sought to address this gap in our knowledge using mouse genetics and TRPM8 antagonism to determine whether TRPM8 channels or neurons are required for migraine-like pain (mechanical allodynia and facial grimace) in inducible migraine models. Our results show that both evoked and spontaneous pain behaviors are dependent on both TRPM8 channels and neurons, as well as required in both acute and chronic migraine models. Moreover, inhibition of TRPM8 channels prevented acute but not established chronic migraine-like pain. These results are consistent with its association with migraine in genetic analyses and establish that TRPM8 channels are a component of the underlying mechanisms of migraine.
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Affiliation(s)
- Chao Wei
- Neuroscience Graduate Program; University of Southern California, 3641 Watt Way / HNB 201, Los Angeles, CA 90089 U.S.A
| | - Brian Kim
- Neurobiology Section; Department of Biological Sciences, University of Southern California, 3641 Watt Way / HNB 201, Los Angeles, CA 90089 U.S.A
| | - David D. McKemy
- Neuroscience Graduate Program; University of Southern California, 3641 Watt Way / HNB 201, Los Angeles, CA 90089 U.S.A
- Neurobiology Section; Department of Biological Sciences, University of Southern California, 3641 Watt Way / HNB 201, Los Angeles, CA 90089 U.S.A
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Grüner J, Stengel H, Werner C, Appeltshauser L, Sommer C, Villmann C, Doppler K. Anti-contactin-1 Antibodies Affect Surface Expression and Sodium Currents in Dorsal Root Ganglia. NEUROLOGY-NEUROIMMUNOLOGY & NEUROINFLAMMATION 2021; 8:8/5/e1056. [PMID: 34429341 PMCID: PMC8407150 DOI: 10.1212/nxi.0000000000001056] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 05/17/2021] [Indexed: 01/13/2023]
Abstract
Background and Objectives As autoantibodies to contactin-1 from patients with chronic inflammatory demyelinating polyradiculoneuropathy not only bind to the paranodes where they are supposed to cause conduction failure but also bind to other neuronal cell types, we aimed to investigate the effect of anti–contactin-1 autoantibodies on contactin-1 surface expression in cerebellar granule neurons, dorsal root ganglion neurons, and contactin-1–transfected human embryonic kidney 293 cells. Methods Immunocytochemistry including structured illumination microscopy and immunoblotting was used to determine expression levels of contactin-1 and/or sodium channels after long-term exposure to autoantibodies from 3 seropositive patients. For functional analysis of sodium channels, whole-cell recordings of sodium currents were performed on dorsal root ganglion neurons incubated with anti–contactin-1 autoantibodies. Results We found a reduction in contactin-1 expression levels on dorsal root ganglion neurons, cerebellar granule neurons, and contactin-1–transfected human embryonic kidney 293 cells and decreased dorsal root ganglion sodium currents after long-term exposure to anti–contactin-1 autoantibodies. Sodium channel density did not decrease. Discussion Our results demonstrate a direct effect of anti–contactin-1 autoantibodies on the surface expression of contactin-1 and sodium currents in dorsal root ganglion neurons. This may be the pathophysiologic correlate of sensory ataxia reported in these patients.
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Affiliation(s)
- Julia Grüner
- From the Department of Neurology (J.G., H.S., L.A., C.S., K.D.), University Hospital Würzburg, Germany; Department of Biotechnology and Biophysics (C.W.), Julius-Maximilians-University of Würzburg; and Institute of Clinical Neurobiology (C.V.), University Hospital, Julius-Maximilians-University of Würzburg, Germany
| | - Helena Stengel
- From the Department of Neurology (J.G., H.S., L.A., C.S., K.D.), University Hospital Würzburg, Germany; Department of Biotechnology and Biophysics (C.W.), Julius-Maximilians-University of Würzburg; and Institute of Clinical Neurobiology (C.V.), University Hospital, Julius-Maximilians-University of Würzburg, Germany
| | - Christian Werner
- From the Department of Neurology (J.G., H.S., L.A., C.S., K.D.), University Hospital Würzburg, Germany; Department of Biotechnology and Biophysics (C.W.), Julius-Maximilians-University of Würzburg; and Institute of Clinical Neurobiology (C.V.), University Hospital, Julius-Maximilians-University of Würzburg, Germany
| | - Luise Appeltshauser
- From the Department of Neurology (J.G., H.S., L.A., C.S., K.D.), University Hospital Würzburg, Germany; Department of Biotechnology and Biophysics (C.W.), Julius-Maximilians-University of Würzburg; and Institute of Clinical Neurobiology (C.V.), University Hospital, Julius-Maximilians-University of Würzburg, Germany
| | - Claudia Sommer
- From the Department of Neurology (J.G., H.S., L.A., C.S., K.D.), University Hospital Würzburg, Germany; Department of Biotechnology and Biophysics (C.W.), Julius-Maximilians-University of Würzburg; and Institute of Clinical Neurobiology (C.V.), University Hospital, Julius-Maximilians-University of Würzburg, Germany
| | - Carmen Villmann
- From the Department of Neurology (J.G., H.S., L.A., C.S., K.D.), University Hospital Würzburg, Germany; Department of Biotechnology and Biophysics (C.W.), Julius-Maximilians-University of Würzburg; and Institute of Clinical Neurobiology (C.V.), University Hospital, Julius-Maximilians-University of Würzburg, Germany
| | - Kathrin Doppler
- From the Department of Neurology (J.G., H.S., L.A., C.S., K.D.), University Hospital Würzburg, Germany; Department of Biotechnology and Biophysics (C.W.), Julius-Maximilians-University of Würzburg; and Institute of Clinical Neurobiology (C.V.), University Hospital, Julius-Maximilians-University of Würzburg, Germany.
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Abstract
Transient receptor potential melastatin 8 (TRPM8) channels play a central role in the detection of environmental cold temperatures in the somatosensory system. TRPM8 is found in a subset of unmyelinated (C-type) afferents located in the dorsal root (DRG) and trigeminal ganglion (TG). Cold hypersensitivity is a common symptom of neuropathic pain conditions caused by cancer therapy, spinal cord injury, viral infection, multiple sclerosis, diabetes, or withdrawal symptoms associated with chronic morphine treatment. Therefore, TRPM8 has received great attention as a therapeutic target. However, as the activity of TRPM8 is unique in sensing cool temperature as well as warming, it is critical to understand the signaling transduction pathways that control modality-specific activity of TRPM8 in healthy versus pathological settings. This review summarizes recent advances in our understanding of the mechanisms involved in the regulation of the TRPM8 activity.
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Affiliation(s)
- Mircea Iftinca
- Department of Physiology and Pharmacology, Inflammation Research Network-Snyder Institute for Chronic Diseases and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary , Calgary, Alberta, Canada
| | - Christophe Altier
- Department of Physiology and Pharmacology, Inflammation Research Network-Snyder Institute for Chronic Diseases and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary , Calgary, Alberta, Canada
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8
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Diminished Cold Avoidance Behaviours after Chronic Cold Exposure - Potential Involvement of TRPM8. Neuroscience 2021; 469:17-30. [PMID: 34139303 DOI: 10.1016/j.neuroscience.2021.06.014] [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: 10/29/2020] [Revised: 06/02/2021] [Accepted: 06/08/2021] [Indexed: 11/22/2022]
Abstract
Ambient temperature changes trigger plastic biological responses. Cold temperature is detected by the somatosensory system and evokes perception of cold together with adaptive physiological responses. We addressed whether chronic cold exposure induces adaptive adjustments of (1) thermosensory behaviours, and (2) the principle molecular cold sensor in the transduction machinery, transient receptor potential melastatin subtype 8 (TRPM8). Mice in two groups were exposed to either cold (6 °C) or thermoneutral (27 °C) ambient temperatures for 4 weeks and subjected to thermosensory behavioural testing. Cold group mice behaved different from Thermoneutral group in the Thermal Gradient Test: the former occupied a wider temperature range and was less cold avoidant. Furthermore, subcutaneous injection of the TRPM8 agonist icilin, enhanced cold avoidance in both groups in the Thermal Gradient Test, but Cold group mice were significantly less affected by icilin. Primary sensory neuron soma are located in dorsal root ganglia (DRGs), and western blotting showed diminished TRPM8 levels in DRGs of Cold group mice, as compared to the Thermoneutral group. We conclude that acclimation to chronic cold altered thermosensory behaviours, so that mice appeared less cold sensitive, and potentially, TRPM8 is involved.
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9
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Rimola V, Osthues T, Königs V, Geißlinger G, Sisignano M. Oxaliplatin Causes Transient Changes in TRPM8 Channel Activity. Int J Mol Sci 2021; 22:4962. [PMID: 34066977 PMCID: PMC8125753 DOI: 10.3390/ijms22094962] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 05/04/2021] [Accepted: 05/05/2021] [Indexed: 02/08/2023] Open
Abstract
Oxaliplatin is a third-generation platinum-based anticancer drug that is widely used as first-line treatment for colorectal carcinoma. Patients treated with oxaliplatin develop an acute peripheral pain several hours after treatment, mostly characterized by cold allodynia as well as a long-term chronic neuropathy. These two phenomena seem to be causally connected. However, the underlying mechanisms that trigger the acute peripheral pain are still poorly understood. Here we show that the activity of the transient receptor potential melastatin 8 (TRPM8) channel but not the activity of any other member of the TRP channel family is transiently increased 1 h after oxaliplatin treatment and decreased 24 h after oxaliplatin treatment. Mechanistically, this is connected with activation of the phospholipase C (PLC) pathway and depletion of phosphatidylinositol 4,5-bisphosphate (PIP2) after oxaliplatin treatment. Inhibition of the PLC pathway can reverse the decreased TRPM8 activity as well as the decreased PIP2-concentrations after oxaliplatin treatment. In summary, these results point out transient changes in TRPM8 activity early after oxaliplatin treatment and a later occurring TRPM8 channel desensitization in primary sensory neurons. These mechanisms may explain the transient cold allodynia after oxaliplatin treatment and highlight an important role of TRPM8 in oxaliplatin-induced acute and neuropathic pain.
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Affiliation(s)
- Vittoria Rimola
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt/ZAFES, University Hospital, Goethe-University, 60590 Frankfurt am Main, Germany; (V.R.); (G.G.)
| | - Tabea Osthues
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany; (T.O.); (V.K.)
| | - Vanessa Königs
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany; (T.O.); (V.K.)
| | - Gerd Geißlinger
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt/ZAFES, University Hospital, Goethe-University, 60590 Frankfurt am Main, Germany; (V.R.); (G.G.)
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany; (T.O.); (V.K.)
| | - Marco Sisignano
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt/ZAFES, University Hospital, Goethe-University, 60590 Frankfurt am Main, Germany; (V.R.); (G.G.)
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany; (T.O.); (V.K.)
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Abstract
Ion channel are embedded in the lipid bilayers of biological membranes. Membrane phospholipids constitute a barrier to ion movement, and they have been considered for a long time as a passive environment for channel proteins. Membrane phospholipids, however, do not only serve as a passive amphipathic environment, but they also modulate channel activity by direct specific lipid-protein interactions. Phosphoinositides are quantitatively minor components of biological membranes, and they play roles in many cellular functions, including membrane traffic, cellular signaling and cytoskeletal organization. Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is mainly found in the inner leaflet of the plasma membrane. Its role as a potential ion channel regulator was first appreciated over two decades ago and by now this lipid is a well-established cofactor or regulator of many different ion channels. The past two decades witnessed the steady development of techniques to study ion channel regulation by phosphoinositides with progress culminating in recent cryoEM structures that allowed visualization of how PI(4,5)P2 opens some ion channels. This chapter will provide an overview of the methods to study regulation by phosphoinositides, focusing on plasma membrane ion channels and PI(4,5)P2.
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11
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Liu L, Rohacs T. Regulation of the cold-sensing TRPM8 channels by phosphoinositides and G q-coupled receptors. Channels (Austin) 2020; 14:79-86. [PMID: 32101066 PMCID: PMC7153793 DOI: 10.1080/19336950.2020.1734266] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 12/23/2019] [Accepted: 12/26/2019] [Indexed: 11/05/2022] Open
Abstract
The Transient Receptor Potential Melastatin 8 (TRPM8) ion channel is an important sensor of environmental cold temperatures. Cold- and menthol-induced activation of this channel requires the presence of the membrane phospholipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. This review discusses recent findings on the role of PI(4,5)P2 and G-proteins in the modulation of TRPM8 upon receptor activation. We will also summarize knowledge on the role of PI(4,5)P2 in Ca2+ dependent desensitization/adaptation of TRPM8 activity, and recent advances in the structural basis of how this lipid binds to TRPM8.
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Affiliation(s)
- Luyu Liu
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Tibor Rohacs
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ, USA
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12
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Paricio-Montesinos R, Schwaller F, Udhayachandran A, Rau F, Walcher J, Evangelista R, Vriens J, Voets T, Poulet JFA, Lewin GR. The Sensory Coding of Warm Perception. Neuron 2020; 106:830-841.e3. [PMID: 32208171 PMCID: PMC7272120 DOI: 10.1016/j.neuron.2020.02.035] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/24/2020] [Accepted: 02/28/2020] [Indexed: 12/26/2022]
Abstract
Humans detect skin temperature changes that are perceived as warm or cool. Like humans, mice report forepaw skin warming with perceptual thresholds of less than 1°C and do not confuse warm with cool. We identify two populations of polymodal C-fibers that signal warm. Warm excites one population, whereas it suppresses the ongoing cool-driven firing of the other. In the absence of the thermosensitive TRPM2 or TRPV1 ion channels, warm perception was blunted, but not abolished. In addition, trpv1:trpa1:trpm3−/− triple-mutant mice that cannot sense noxious heat detected skin warming, albeit with reduced sensitivity. In contrast, loss or local pharmacological silencing of the cool-driven TRPM8 channel abolished the ability to detect warm. Our data are not reconcilable with a labeled line model for warm perception, with receptors firing only in response to warm stimuli, but instead support a conserved dual sensory model to unambiguously detect skin warming in vertebrates. Mice, like humans, perceive forepaw warming (≥1°C) and discriminate warm from cool Warm-activated and warm-silenced polymodal C-fibers both signal forepaw warming Mice lacking the cool-sensitive ion channel TRPM8 are unable to perceive warm The inability to perceive warm is associated with loss of warm-silenced C-fibers
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Affiliation(s)
- Ricardo Paricio-Montesinos
- Department of Neuroscience, Max Delbrück Center for Molecular Medicine, Robert-Rössle Straße 10, 13092 Berlin, Germany; Neuroscience Research Center and Cluster of Excellence NeuroCure, Charité-Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
| | - Frederick Schwaller
- Department of Neuroscience, Max Delbrück Center for Molecular Medicine, Robert-Rössle Straße 10, 13092 Berlin, Germany
| | - Annapoorani Udhayachandran
- Department of Neuroscience, Max Delbrück Center for Molecular Medicine, Robert-Rössle Straße 10, 13092 Berlin, Germany; Neuroscience Research Center and Cluster of Excellence NeuroCure, Charité-Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
| | - Florian Rau
- Department of Neuroscience, Max Delbrück Center for Molecular Medicine, Robert-Rössle Straße 10, 13092 Berlin, Germany; Neuroscience Research Center and Cluster of Excellence NeuroCure, Charité-Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
| | - Jan Walcher
- Department of Neuroscience, Max Delbrück Center for Molecular Medicine, Robert-Rössle Straße 10, 13092 Berlin, Germany
| | - Roberta Evangelista
- Department of Neuroscience, Max Delbrück Center for Molecular Medicine, Robert-Rössle Straße 10, 13092 Berlin, Germany
| | - Joris Vriens
- Laboratory of Endometrium, Endometriosis and Reproductive Medicine, KU Leuven Department of Development and Regeneration, G-PURE, Leuven, Belgium
| | - Thomas Voets
- Laboratory of Ion Channel Research, VIB-KU Leuven Center for Brain and Disease Research, KU Leuven Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - James F A Poulet
- Department of Neuroscience, Max Delbrück Center for Molecular Medicine, Robert-Rössle Straße 10, 13092 Berlin, Germany; Neuroscience Research Center and Cluster of Excellence NeuroCure, Charité-Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany.
| | - Gary R Lewin
- Department of Neuroscience, Max Delbrück Center for Molecular Medicine, Robert-Rössle Straße 10, 13092 Berlin, Germany.
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Chen C, Zhang J, Sun L, Zhang Y, Gan WB, Tang P, Yang G. Long-term imaging of dorsal root ganglia in awake behaving mice. Nat Commun 2019; 10:3087. [PMID: 31300648 PMCID: PMC6625980 DOI: 10.1038/s41467-019-11158-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 06/26/2019] [Indexed: 01/26/2023] Open
Abstract
The dorsal root ganglia (DRG) contain the somas of first-order sensory neurons critical for somatosensation. Due to technical difficulties, DRG neuronal activity in awake behaving animals remains unknown. Here, we develop a method for imaging DRG at cellular and subcellular resolution over weeks in awake mice. The method involves the installation of an intervertebral fusion mount to reduce spinal movement, and the implantation of a vertebral glass window without interfering animals' motor and sensory functions. In vivo two-photon calcium imaging shows that DRG neuronal activity is higher in awake than anesthetized animals. Immediately after plantar formalin injection, DRG neuronal activity increases substantially and this activity upsurge correlates with animals' phasic pain behavior. Repeated imaging of DRG over 5 weeks after formalin injection reveals persistent neuronal hyperactivity associated with ongoing pain. The method described here provides an important means for in vivo studies of DRG functions in sensory perception and disorders.
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Affiliation(s)
- Chao Chen
- Department of Orthopaedics, Peking 301 Hospital, Beijing, 100853, China
| | - Jinhui Zhang
- Department of Orthopaedics, the Affiliated Southeast Hospital of Xiamen University, Zhangzhou 175 Hospital, Zhangzhou, 363000, China
| | - Linlin Sun
- Department of Anesthesiology, Columbia University, New York, 10032, NY, USA
| | - Yiling Zhang
- Department of Orthopaedics, Peking 301 Hospital, Beijing, 100853, China
| | - Wen-Biao Gan
- Department of Neuroscience and Physiology, Department of Anesthesiology, Skirball Institute, New York University School of Medicine, New York, 10016, NY, USA.
| | - Peifu Tang
- Department of Orthopaedics, Peking 301 Hospital, Beijing, 100853, China.
| | - Guang Yang
- Department of Anesthesiology, Columbia University, New York, 10032, NY, USA.
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14
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Yudin Y, Rohacs T. The G-protein-biased agents PZM21 and TRV130 are partial agonists of μ-opioid receptor-mediated signalling to ion channels. Br J Pharmacol 2019; 176:3110-3125. [PMID: 31074038 DOI: 10.1111/bph.14702] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 04/10/2019] [Accepted: 04/13/2019] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND AND PURPOSE Opioids remain the most efficient medications against severe pain; they act on receptors that couple to heterotrimeric G-proteins in the Gαi/o family. Opioids exert many of their acute effects through modulating ion channels via Gβγ subunits. Many of their side effects are attributed to β-arrestin recruitment. Several biased agonists that do not recruit β-arrestins, but activate G-protein-dependent pathways, have recently been developed. While these compounds have been proposed to be full agonists of G-protein signalling in several high throughput pharmacological assays, their effects were not studied on ion channel targets. EXPERIMENTAL APPROACH Here, we used patch-clamp electrophysiology and Ca2+ imaging to test the effects of TRV130, PZM21, and herkinorin, three G-protein-biased agonists of μ-opioid receptors, on ion channel targets of Gαi/o /Gβγ signalling. We also studied G-protein dissociation using a FRET-based assay. KEY RESULTS All three biased agonists induced smaller activation of G-protein-coupled inwardly rectifying K+ channels (Kir 3.2) and smaller inhibition of transient receptor potential melastatin (TRPM3) channels than the full μ receptor agonist DAMGO. Co-application of TRV130 or PZM21, but not herkinorin, alleviated the effects of DAMGO on both channels. PZM21 and TRV130 also decreased the effect of morphine on Kir 3.2 channels. The CaV 2.2 channel was also inhibited less by PZM21 and TRV130 than by DAMGO. We also found that TRV130, PZM21, and herkinorin were less effective than DAMGO at inducing dissociation of the Gαi /Gβγ complex. CONCLUSION AND IMPLICATIONS TRV130, PZM21, and potentially herkinorin are partial agonists of μ receptors.
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Affiliation(s)
- Yevgen Yudin
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, Newark, New Jersey
| | - Tibor Rohacs
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, Newark, New Jersey
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15
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G αq Sensitizes TRPM8 to Inhibition by PI(4,5)P 2 Depletion upon Receptor Activation. J Neurosci 2019; 39:6067-6080. [PMID: 31127000 DOI: 10.1523/jneurosci.2304-18.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 04/26/2019] [Accepted: 04/29/2019] [Indexed: 02/07/2023] Open
Abstract
The cold- and menthol-sensitive transient receptor potential melastatin 8 (TRPM8) channel is important for both physiological temperature detection and cold allodynia. Activation of G-protein-coupled receptors (GPCRs) by proinflammatory mediators inhibits these channels. It was proposed that this inhibition proceeds via direct binding of G αq to the channel. TRPM8 requires the plasma membrane phospholipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2 or PIP2] for activity. However, it was claimed that a decrease in cellular levels of this lipid upon receptor activation does not contribute to channel inhibition. Here, we show that supplementing the whole-cell patch pipette with PI(4,5)P2 reduced inhibition of TRPM8 by activation of Gαq-coupled receptors in mouse dorsal root ganglion (DRG) neurons isolated from both sexes. Stimulating the same receptors activated phospholipase C (PLC) and decreased plasma membrane PI(4,5)P2 levels in these neurons. PI(4,5)P2 also reduced inhibition of TRPM8 by activation of heterologously expressed muscarinic M1 receptors. Coexpression of a constitutively active G αq protein that does not couple to PLC inhibited TRPM8 activity, and in cells expressing this protein, decreasing PI(4,5)P2 levels using a voltage-sensitive 5'-phosphatase induced a stronger inhibition of TRPM8 activity than in control cells. Our data indicate that, upon GPCR activation, G αq binding reduces the apparent affinity of TRPM8 for PI(4,5)P2 and thus sensitizes the channel to inhibition induced by decreasing PI(4,5)P2 levels.SIGNIFICANCE STATEMENT Increased sensitivity to heat in inflammation is partially mediated by inhibition of the cold- and menthol-sensitive transient receptor potential melastatin 8 (TRPM8) ion channels. Most inflammatory mediators act via G-protein-coupled receptors that activate the phospholipase C pathway, leading to the hydrolysis of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. How receptor activation by inflammatory mediators leads to TRPM8 inhibition is not well understood. Here, we propose that direct binding of G αq both reduces TRPM8 activity and sensitizes the channel to inhibition by decreased levels of its cofactor, PI(4,5)P2 Our data demonstrate the convergence of two downstream effectors of receptor activation, G αq and PI(4,5)P2 hydrolysis, in the regulation of TRPM8.
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16
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Hatta A, Kurose M, Sullivan C, Okamoto K, Fujii N, Yamamura K, Meng ID. Dry eye sensitizes cool cells to capsaicin-induced changes in activity via TRPV1. J Neurophysiol 2019; 121:2191-2201. [PMID: 30969886 DOI: 10.1152/jn.00126.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Corneal cool cells are sensitive to the ocular fluid status of the corneal surface and may be responsible for the regulation of basal tear production. Previously, we have shown that dry eye, induced by lacrimal gland excision (LGE) in rats, sensitized corneal cool cells to the transient receptor potential melastatin 8 (TRPM8) agonist menthol and to cool stimulation. In the present study, we examined the effect of dry eye on the sensitivity of cool cells to the transient receptor potential vanilloid 1 (TRPV1) agonist capsaicin. Single-unit recordings in the trigeminal ganglion were performed 7-10 days after LGE. At a concentration of 0.3 μM, capsaicin did not affect ongoing or cool-evoked activity in control animals yet facilitated ongoing activity and suppressed cool-evoked activity in LGE animals. At higher concentrations (3 μM), capsaicin continued to facilitate ongoing activity in LGE animals but suppressed ongoing activity in control animals. Higher concentrations of capsaicin also suppressed cool-evoked activity in both groups of animals, with an overall greater effect in LGE animals. In addition to altering cool-evoked activity, capsaicin enhanced the sensitivity of cool cells to heat in LGE animals. Capsaicin-induced changes were prevented by the application of the TRPV1 antagonist capsazepine. With the use of fluorescent in situ hybridization, TRPV1 and TRPM8 expression was examined in retrograde tracer-identified corneal neurons. The coexpression of TRPV1 and TRPM8 in corneal neurons was significantly greater in LGE-treated animals when compared with sham controls. These results indicate that LGE-induced dry eye increases TRPV1-mediated responses in corneal cool cells at least in part through the increased expression of TRPV1. NEW & NOTEWORTHY Corneal cool cells are known to detect drying of the ocular surface. Our study is the first to report that dry eye induced alterations in cool cell response properties, including the increased responsiveness to noxious heat and activation by capsaicin. Along with the changes in cell response properties, it is possible these neurons also function differently in dry eye, relaying information related to the perception of ocular irritation in addition to regulating tearing and blinking.
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Affiliation(s)
- Azusa Hatta
- Division of Oral Physiology, Department of Oral Biological Sciences, Niigata University, Graduate School of Medical and Dental Sciences , Niigata , Japan.,General Dentistry and Clinical Education Unit, Niigata University Medical and Dental Hospital , Niigata , Japan
| | - Masayuki Kurose
- Division of Oral Physiology, Department of Oral Biological Sciences, Niigata University, Graduate School of Medical and Dental Sciences , Niigata , Japan
| | - Cara Sullivan
- Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, Maine.,Graduate Studies in Biomedical Sciences and Engineering, University of Maine , Orono, Maine
| | - Keiichiro Okamoto
- Division of Oral Physiology, Department of Oral Biological Sciences, Niigata University, Graduate School of Medical and Dental Sciences , Niigata , Japan
| | - Noritaka Fujii
- General Dentistry and Clinical Education Unit, Niigata University Medical and Dental Hospital , Niigata , Japan
| | - Kensuke Yamamura
- Division of Oral Physiology, Department of Oral Biological Sciences, Niigata University, Graduate School of Medical and Dental Sciences , Niigata , Japan
| | - Ian D Meng
- Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, Maine
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17
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Noyer L, Grolez GP, Prevarskaya N, Gkika D, Lemonnier L. TRPM8 and prostate: a cold case? Pflugers Arch 2018; 470:1419-1429. [PMID: 29926226 DOI: 10.1007/s00424-018-2169-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/08/2018] [Accepted: 06/12/2018] [Indexed: 12/19/2022]
Abstract
While originally cloned from the prostate in 2001, transient receptor potential, melastatin member 8 (TRPM8) has since been identified as the cold/menthol receptor in the peripheral nervous system. This discovery has led to hundreds of studies regarding the role of this channel in pain and thermosensation phenomena, while relegating TRPM8 involvement in cancer to a secondary role. Despite these findings, there is growing evidence that TRPM8 should be carefully studied within the frame of carcinogenesis, especially in the prostate, where it is highly expressed and where many teams have confirmed variations in its expression during cancer progression. Its regulation by physiological factors, such as PSA and androgens, has proved that TRPM8 can exhibit an activity beyond that of a cold receptor, thus explaining how the channel can be activated in organs not exposed to temperature variations. With this review, we aim to provide a brief overview of the current knowledge regarding the complex roles of TRPM8 in prostate carcinogenesis and to show that this research path still represents a "hot" topic with potential clinical applications in the short term.
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Affiliation(s)
- Lucile Noyer
- Inserm, U1003, Laboratory of Cell Physiology, University Lille Nord de France, 59655 Cedex, Villeneuve d'Ascq, France
- Laboratory of Excellence, Ion Channels Science and Therapeutics, Villeneuve d'Ascq, France
| | - Guillaume P Grolez
- Inserm, U1003, Laboratory of Cell Physiology, University Lille Nord de France, 59655 Cedex, Villeneuve d'Ascq, France
- Laboratory of Excellence, Ion Channels Science and Therapeutics, Villeneuve d'Ascq, France
| | - Natalia Prevarskaya
- Inserm, U1003, Laboratory of Cell Physiology, University Lille Nord de France, 59655 Cedex, Villeneuve d'Ascq, France
- Laboratory of Excellence, Ion Channels Science and Therapeutics, Villeneuve d'Ascq, France
| | - Dimitra Gkika
- Inserm, U1003, Laboratory of Cell Physiology, University Lille Nord de France, 59655 Cedex, Villeneuve d'Ascq, France
- Laboratory of Excellence, Ion Channels Science and Therapeutics, Villeneuve d'Ascq, France
| | - Loic Lemonnier
- Inserm, U1003, Laboratory of Cell Physiology, University Lille Nord de France, 59655 Cedex, Villeneuve d'Ascq, France.
- Laboratory of Excellence, Ion Channels Science and Therapeutics, Villeneuve d'Ascq, France.
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18
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Ca 2+ Regulation of TRP Ion Channels. Int J Mol Sci 2018; 19:ijms19041256. [PMID: 29690581 PMCID: PMC5979445 DOI: 10.3390/ijms19041256] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 04/16/2018] [Accepted: 04/17/2018] [Indexed: 12/20/2022] Open
Abstract
Ca2+ signaling influences nearly every aspect of cellular life. Transient receptor potential (TRP) ion channels have emerged as cellular sensors for thermal, chemical and mechanical stimuli and are major contributors to Ca2+ signaling, playing an important role in diverse physiological and pathological processes. Notably, TRP ion channels are also one of the major downstream targets of Ca2+ signaling initiated either from TRP channels themselves or from various other sources, such as G-protein coupled receptors, giving rise to feedback regulation. TRP channels therefore function like integrators of Ca2+ signaling. A growing body of research has demonstrated different modes of Ca2+-dependent regulation of TRP ion channels and the underlying mechanisms. However, the precise actions of Ca2+ in the modulation of TRP ion channels remain elusive. Advances in Ca2+ regulation of TRP channels are critical to our understanding of the diversified functions of TRP channels and complex Ca2+ signaling.
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19
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Badheka D, Yudin Y, Borbiro I, Hartle CM, Yazici A, Mirshahi T, Rohacs T. Inhibition of Transient Receptor Potential Melastatin 3 ion channels by G-protein βγ subunits. eLife 2017; 6. [PMID: 28829742 PMCID: PMC5593506 DOI: 10.7554/elife.26147] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 06/28/2017] [Indexed: 11/26/2022] Open
Abstract
Transient receptor potential melastatin 3 (TRPM3) channels are activated by heat, and chemical ligands such as pregnenolone sulphate (PregS) and CIM0216. Here, we show that activation of receptors coupled to heterotrimeric Gi/o proteins inhibits TRPM3 channels. This inhibition was alleviated by co-expression of proteins that bind the βγ subunits of heterotrimeric G-proteins (Gβγ). Co-expression of Gβγ, but not constitutively active Gαi or Gαo, inhibited TRPM3 currents. TRPM3 co-immunoprecipitated with Gβ, and purified Gβγ proteins applied to excised inside-out patches inhibited TRPM3 currents, indicating a direct effect. Baclofen and somatostatin, agonists of Gi-coupled receptors, inhibited Ca2+ signals induced by PregS and CIM0216 in mouse dorsal root ganglion (DRG) neurons. The GABAB receptor agonist baclofen also inhibited inward currents induced by CIM0216 in DRG neurons, and nocifensive responses elicited by this TRPM3 agonist in mice. Our data uncover a novel signaling mechanism regulating TRPM3 channels. DOI:http://dx.doi.org/10.7554/eLife.26147.001
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Affiliation(s)
- Doreen Badheka
- New Jersey Medical School, Rutgers, the State University of New Jersey, Newark, United States
| | - Yevgen Yudin
- New Jersey Medical School, Rutgers, the State University of New Jersey, Newark, United States
| | - Istvan Borbiro
- New Jersey Medical School, Rutgers, the State University of New Jersey, Newark, United States
| | - Cassandra M Hartle
- Department of Molecular and Functional Genomics, Weis Center for Research, Geisinger Clinic, Danville, United States
| | - Aysenur Yazici
- New Jersey Medical School, Rutgers, the State University of New Jersey, Newark, United States
| | - Tooraj Mirshahi
- Department of Molecular and Functional Genomics, Weis Center for Research, Geisinger Clinic, Danville, United States
| | - Tibor Rohacs
- New Jersey Medical School, Rutgers, the State University of New Jersey, Newark, United States
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20
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Winter Z, Gruschwitz P, Eger S, Touska F, Zimmermann K. Cold Temperature Encoding by Cutaneous TRPA1 and TRPM8-Carrying Fibers in the Mouse. Front Mol Neurosci 2017; 10:209. [PMID: 28713241 PMCID: PMC5492152 DOI: 10.3389/fnmol.2017.00209] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 06/14/2017] [Indexed: 11/30/2022] Open
Abstract
Previous research identified TRPM8 and TRPA1 cold transducers with separate functions, one being functional in the non-noxious range and the second one being a nociceptive transducer. TRPM8-deficient mice present overt deficits in the detection of environmental cool, but not a lack of cold avoidance and TRPA1-deficient mice show clear deficits in some cold nocifensive assays. The extent of TRPA1's contribution to cold sensing in vivo is still unclear, because mice lacking both TRPM8 and TRPA1 (DKO) were described with unchanged cold avoidance from TRPM8−/− based on a two-temperature-choice assay and by c-fos measurement. The present study was designed to differentiate how much TRPM8 alone and combined TRPA1 and TRPM8 contribute to cold sensing. We analyzed behavior in the thermal ring track assay adjusted between 30 and 5°C and found a large reduction in cold avoidance of the double knockout mice as compared to the TRPM8-deficient mice. We also revisited skin-nerve recordings from saphenous-nerve skin preparations with regard to nociceptors and thermoreceptors. We compared the frequency and characteristics of the cold responses of TRPM8-expressing and TRPM8-negative C-fiber nociceptors in C57BL/6J mice with nociceptors of TRPM8-deficient and DKO mice and found that TRPM8 enables nociceptors to encode cold temperatures with higher firing rates and larger responses with sustained, static component. In TRPM8−/−, C-fiber cold nociceptors were markedly reduced and appeared further reduced in DKO. Nevertheless, the remaining cold responses in both knockout strains were similar in their characteristics and they were indifferent from the TRPM8-negative cold responses found in C57BL/6J mice. TRPM8 had a comparably essential role for encoding cold in thermoreceptors and lack of TRPM8 reduced response magnitude, peak and mean firing rates and the incidence of thermoreceptors. The encoding deficits were similar in the DKO strain. Our data illustrate that lack of TRPA1 in TRPM8-deficient mice results in a disproportionately large reduction in cold avoidance behavior and also affects the incidence of cold encoding fiber types. Presumably TRPA1 compensates for lack of TRPM8 to a certain extent and both channels cooperate to cover the entire cold temperature range, making cold-temperature encoding by TRPA1—although less powerful—synergistic to TRPM8.
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Affiliation(s)
- Zoltan Winter
- Department of Anesthesiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-NürnbergErlangen, Germany
| | - Philipp Gruschwitz
- Department of Anesthesiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-NürnbergErlangen, Germany
| | - Stephanie Eger
- Department of Anesthesiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-NürnbergErlangen, Germany
| | - Filip Touska
- Department of Anesthesiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-NürnbergErlangen, Germany
| | - Katharina Zimmermann
- Department of Anesthesiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-NürnbergErlangen, Germany
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21
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Role of the Excitability Brake Potassium Current I KD in Cold Allodynia Induced by Chronic Peripheral Nerve Injury. J Neurosci 2017; 37:3109-3126. [PMID: 28179555 DOI: 10.1523/jneurosci.3553-16.2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 01/24/2017] [Accepted: 01/26/2017] [Indexed: 11/21/2022] Open
Abstract
Cold allodynia is a common symptom of neuropathic and inflammatory pain following peripheral nerve injury. The mechanisms underlying this disabling sensory alteration are not entirely understood. In primary somatosensory neurons, cold sensitivity is mainly determined by a functional counterbalance between cold-activated TRPM8 channels and Shaker-like Kv1.1-1.2 channels underlying the excitability brake current IKD Here we studied the role of IKD in damage-triggered painful hypersensitivity to innocuous cold. We found that cold allodynia induced by chronic constriction injury (CCI) of the sciatic nerve in mice, was related to both an increase in the proportion of cold-sensitive neurons (CSNs) in DRGs contributing to the sciatic nerve, and a decrease in their cold temperature threshold. IKD density was reduced in high-threshold CSNs from CCI mice compared with sham animals, with no differences in cold-induced TRPM8-dependent current density. The electrophysiological properties and neurochemical profile of CSNs revealed an increase of nociceptive-like phenotype among neurons from CCI animals compared with sham mice. These results were validated using a mathematical model of CSNs, including IKD and TRPM8, showing that a reduction in IKD current density shifts the thermal threshold to higher temperatures and that the reduction of this current induces cold sensitivity in former cold-insensitive neurons expressing low levels of TRPM8-like current. Together, our results suggest that cold allodynia is largely due to a functional downregulation of IKD in both high-threshold CSNs and in a subpopulation of polymodal nociceptors expressing TRPM8, providing a general molecular and neural mechanism for this sensory alteration.SIGNIFICANCE STATEMENT This paper unveils the critical role of the brake potassium current IKD in damage-triggered cold allodynia. Using a well-known form of nerve injury and combining behavioral analysis, calcium imaging, patch clamping, and pharmacological tools, validated by mathematical modeling, we determined that the functional expression of IKD is reduced in sensory neurons in response to peripheral nerve damage. This downregulation not only enhances cold sensitivity of high-threshold cold thermoreceptors signaling cold discomfort, but it also transforms a subpopulation of polymodal nociceptors signaling pain into neurons activated by mild temperature drops. Our results suggest that cold allodynia is linked to a reduction of IKD in both high-threshold cold thermoreceptors and nociceptors expressing TRPM8, providing a general model for this form of cold-induced pain.
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