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Schumacher MA. Peripheral Neuroinflammation and Pain: How Acute Pain Becomes Chronic. Curr Neuropharmacol 2024; 22:6-14. [PMID: 37559537 PMCID: PMC10716877 DOI: 10.2174/1570159x21666230808111908] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/05/2023] [Accepted: 04/26/2023] [Indexed: 08/11/2023] Open
Abstract
The number of individuals suffering from severe chronic pain and its social and financial impact is staggering. Without significant advances in our understanding of how acute pain becomes chronic, effective treatments will remain out of reach. This mini review will briefly summarize how critical signaling pathways initiated during the early phases of peripheral nervous system inflammation/ neuroinflammation establish long-term modifications of sensory neuronal function. Together with the recruitment of non-neuronal cellular elements, nociceptive transduction is transformed into a pathophysiologic state sustaining chronic peripheral sensitization and pain. Inflammatory mediators, such as nerve growth factor (NGF), can lower activation thresholds of sensory neurons through posttranslational modification of the pain-transducing ion channels transient-receptor potential TRPV1 and TRPA1. Performing a dual role, NGF also drives increased expression of TRPV1 in sensory neurons through the recruitment of transcription factor Sp4. More broadly, Sp4 appears to modulate a nociceptive transcriptome including TRPA1 and other genes encoding components of pain transduction. Together, these findings suggest a model where acute pain evoked by peripheral injury-induced inflammation becomes persistent through repeated cycles of TRP channel modification, Sp4-dependent overexpression of TRP channels and ongoing production of inflammatory mediators.
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Affiliation(s)
- Mark A Schumacher
- Department of Anesthesia and Perioperative Care and the UCSF Pain and Addiction Research Center, University of California, San Francisco, California, 94143 USA
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2
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Mecawi AS, Varanda WA, da Silva MP. Osmoregulation and the Hypothalamic Supraoptic Nucleus: From Genes to Functions. Front Physiol 2022; 13:887779. [PMID: 35685279 PMCID: PMC9171026 DOI: 10.3389/fphys.2022.887779] [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: 03/02/2022] [Accepted: 04/18/2022] [Indexed: 11/13/2022] Open
Abstract
Due to the relatively high permeability to water of the plasma membrane, water tends to equilibrate its chemical potential gradient between the intra and extracellular compartments. Because of this, changes in osmolality of the extracellular fluid are accompanied by changes in the cell volume. Therefore, osmoregulatory mechanisms have evolved to keep the tonicity of the extracellular compartment within strict limits. This review focuses on the following aspects of osmoregulation: 1) the general problems in adjusting the "milieu interieur" to challenges imposed by water imbalance, with emphasis on conceptual aspects of osmosis and cell volume regulation; 2) osmosensation and the hypothalamic supraoptic nucleus (SON), starting with analysis of the electrophysiological responses of the magnocellular neurosecretory cells (MNCs) involved in the osmoreception phenomenon; 3) transcriptomic plasticity of SON during sustained hyperosmolality, to pinpoint the genes coding membrane channels and transporters already shown to participate in the osmosensation and new candidates that may have their role further investigated in this process, with emphasis on those expressed in the MNCs, discussing the relationships of hydration state, gene expression, and MNCs electrical activity; and 4) somatodendritic release of neuropeptides in relation to osmoregulation. Finally, we expect that by stressing the relationship between gene expression and the electrical activity of MNCs, studies about the newly discovered plastic-regulated genes that code channels and transporters in the SON may emerge.
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Affiliation(s)
- André Souza Mecawi
- Laboratory of Molecular Neuroendocrinology, Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
| | - Wamberto Antonio Varanda
- Department of Physiology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Melina Pires da Silva
- Laboratory of Cellular Neuroendocrinology, Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
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Luu DD, Owens AM, Mebrat MD, Van Horn WD. A molecular perspective on identifying TRPV1 thermosensitive regions and disentangling polymodal activation. Temperature (Austin) 2021; 10:67-101. [PMID: 37187836 PMCID: PMC10177694 DOI: 10.1080/23328940.2021.1983354] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 09/10/2021] [Accepted: 09/16/2021] [Indexed: 10/20/2022] Open
Abstract
TRPV1 is a polymodal receptor ion channel that is best known to function as a molecular thermometer. It is activated in diverse ways, including by heat, protons (low pH), and vanilloid compounds, such as capsaicin. In this review, we summarize molecular studies of TRPV1 thermosensing, focusing on the cross-talk between heat and other activation modes. Additional insights from TRPV1 isoforms and non-rodent/non-human TRPV1 ortholog studies are also discussed in this context. While the molecular mechanism of heat activation is still emerging, it is clear that TRPV1 thermosensing is modulated allosterically, i.e., at a distance, with contributions from many distinct regions of the channel. Similarly, current studies identify cross-talk between heat and other TRPV1 activation modes, such as protons and capsaicin, and that these modes can generally be selectively disentangled. In aggregate, this suggests that future TRPV1 molecular studies should define allosteric pathways and provide mechanistic insight, thereby enabling mode-selective manipulation of the polymodal receptor. These advances are anticipated to have significant implications in both basic and applied biomedical sciences.
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Affiliation(s)
- Dustin D. Luu
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- The Biodesign Institute Virginia G. Piper Center for Personalized Diagnostics,Arizona State University, Tempe, Arizona,USA
| | - Aerial M. Owens
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- The Biodesign Institute Virginia G. Piper Center for Personalized Diagnostics,Arizona State University, Tempe, Arizona,USA
| | - Mubark D. Mebrat
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- The Biodesign Institute Virginia G. Piper Center for Personalized Diagnostics,Arizona State University, Tempe, Arizona,USA
| | - Wade D. Van Horn
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- The Biodesign Institute Virginia G. Piper Center for Personalized Diagnostics,Arizona State University, Tempe, Arizona,USA
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Multiple single nucleotide polymorphisms of the transient receptor potential vanilloid 1 (TRPV1) genes associate with cough sensitivity to capsaicin in healthy subjects. Pulm Pharmacol Ther 2020; 61:101889. [PMID: 31935455 DOI: 10.1016/j.pupt.2020.101889] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 01/10/2020] [Accepted: 01/10/2020] [Indexed: 01/18/2023]
Abstract
BACKGROUND Cough is a common symptom in several respiratory diseases and may occur in healthy subjects as a defense mechanism against noxious inhalants. Cough response is mediated by transient receptor potential vanilloid-1 (TRPV1) expressed by C-fibers in the airways. Capsaicin (CPS) activates TRPV1 and is regularly used as a tool to study cough response. Although single nucleotide polymorphisms (SNPs) of TRPV1 are implicated in CPS binding, their role in cough response is not fully elucidated. AIMS In this study we investigated the relationship between capsaicin cough challenge sensitivity and multiple TRPV1 polymorphisms. METHODS The dose-response of cough induced by CPS inhalation was determined in 20 unselected healthy volunteers and the concentration of CPS causing two coughs (C2) was calculated. The SNPs I585V(rs8065080), T505A(rs17633288), T469I(rs224534), I315 M(rs222747), P91S(rs222749), and K2N(rs9894618) were characterized in blood DNA from each subject. The association between combinations of TRPV1 SNPs and CPS sensitivity of each subject was assessed by linear regression. RESULTS All subjects were wild type for T505A and K2N, while they exhibited two to six SNPs with high capsaicin responsiveness. The major contribution to CPS sensitivity in vivo (C2) was due to four combined SNPs: 315 M, 585I, 469I and 91S (p = 0.015). We found, however, that the presence of a minimum of two polymorphisms, such as 91S combined with 315 M (p = 0.032) or 91S with 585I (p = 0.025), was sufficient to detect an effect on C2. CONCLUSION Capsaicin cough challenge sensitivity in healthy subjects is dependent on multiple TRPV1 polymorphisms.
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Sheehan K, Lee J, Chong J, Zavala K, Sharma M, Philipsen S, Maruyama T, Xu Z, Guan Z, Eilers H, Kawamata T, Schumacher M. Transcription factor Sp4 is required for hyperalgesic state persistence. PLoS One 2019; 14:e0211349. [PMID: 30811405 PMCID: PMC6392229 DOI: 10.1371/journal.pone.0211349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 01/11/2019] [Indexed: 12/14/2022] Open
Abstract
Understanding how painful hypersensitive states develop and persist beyond the initial hours to days is critically important in the effort to devise strategies to prevent and/or reverse chronic painful states. Changes in nociceptor transcription can alter the abundance of nociceptive signaling elements, resulting in longer-term change in nociceptor phenotype. As a result, sensitized nociceptive signaling can be further amplified and nocifensive behaviors sustained for weeks to months. Building on our previous finding that transcription factor Sp4 positively regulates the expression of the pain transducing channel TRPV1 in Dorsal Root Ganglion (DRG) neurons, we sought to determine if Sp4 serves a broader role in the development and persistence of hypersensitive states in mice. We observed that more than 90% of Sp4 staining DRG neurons were small to medium sized, primarily unmyelinated (NF200 neg) and the majority co-expressed nociceptor markers TRPV1 and/or isolectin B4 (IB4). Genetically modified mice (Sp4+/-) with a 50% reduction of Sp4 showed a reduction in DRG TRPV1 mRNA and neuronal responses to the TRPV1 agonist-capsaicin. Importantly, Sp4+/- mice failed to develop persistent inflammatory thermal hyperalgesia, showing a reversal to control values after 6 hours. Despite a reversal of inflammatory thermal hyperalgesia, there was no difference in CFA-induced hindpaw swelling between CFA Sp4+/- and CFA wild type mice. Similarly, Sp4+/- mice failed to develop persistent mechanical hypersensitivity to hind-paw injection of NGF. Although Sp4+/- mice developed hypersensitivity to traumatic nerve injury, Sp4+/- mice failed to develop persistent cold or mechanical hypersensitivity to the platinum-based chemotherapeutic agent oxaliplatin, a non-traumatic model of neuropathic pain. Overall, Sp4+/- mice displayed a remarkable ability to reverse the development of multiple models of persistent inflammatory and neuropathic hypersensitivity. This suggests that Sp4 functions as a critical control point for a network of genes that conspire in the persistence of painful hypersensitive states.
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Affiliation(s)
- Kayla Sheehan
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California, United States of America
| | - Jessica Lee
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California, United States of America
| | - Jillian Chong
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California, United States of America
| | - Kathryn Zavala
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California, United States of America
| | - Manohar Sharma
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California, United States of America
| | - Sjaak Philipsen
- Department of Cell Biology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Tomoyuki Maruyama
- Department of Anesthesiology, Wakayama Medical University, Wakayama, Japan
| | - Zheyun Xu
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California, United States of America
| | - Zhonghui Guan
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California, United States of America
| | - Helge Eilers
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California, United States of America
| | - Tomoyuki Kawamata
- Department of Anesthesiology, Wakayama Medical University, Wakayama, Japan
| | - Mark Schumacher
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California, United States of America
- * E-mail:
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Sun L, Wang X, Zhang Y, Wang T, Li X, Ma Y. The evaluation of neural and vascular hyper-reactivity for sensitive skin. Skin Res Technol 2016; 22:381-7. [PMID: 26841957 DOI: 10.1111/srt.12278] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2015] [Indexed: 12/15/2022]
Abstract
BACKGROUND The impaired barrier function has been studied comprehensively but few about the heighted neural and vascular reaction for the pathogenesis of sensitive skin. METHODS Lactic acid stinging test (LAST) was used to identify sensitive subjects in selection phase. In the subsequent test phase, the baseline value of the blood flow (BF) and the current perception threshold (CPT) was measured by non-invasive instruments firstly. Then, the 0.001% capsaicin was applied to the nasolabial fold for 5 min. After the capsaicin test (CAT), the BF (immediately after the CAT) and CPT (1 h later after the CAT) were measured again. Blood sample were collected for genetic analysis of four TRPV1 gene single nucleotide polymorphisms between the positive-group and the negative-group. RESULT The positive-group had lower baseline value of CPT at 5 and 250 Hz compared with the negative-group, but no difference in baseline value of BF. After the CAT, significant variation in CPT at 5 and 250 Hz values and the BF were found in positive-group but not in negative-group. The genotype frequencies of AG/GG in RS224534 and AC/CC in RS4790523 in positive-group were higher than that of negative-group. CONCLUSION The sensitive subjects were prone to be stimulated by capsaicin to trigger neural and vascular hyper-reactivity. The genetic variation of TRPV1 and the unpleasant sensation demonstrate that TRPV1 play an important role in the pathogenesis of sensitive skin. Our study supports that sensory irritation inhibitors and anti-inflammatory compounds should be considered to be added in cosmetics to reduce the heighted neural and vascular reaction of sensitive skin.
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Affiliation(s)
- L Sun
- Shanghai Skin Disease Hospital Clinical School of Anhui Medical University, Shanghai, China.,Skin & Cosmetic Research Department, Shanghai Skin Disease Hospital, Shanghai, China
| | - X Wang
- Skin & Cosmetic Research Department, Shanghai Skin Disease Hospital, Shanghai, China
| | - Y Zhang
- Skin & Cosmetic Research Department, Shanghai Skin Disease Hospital, Shanghai, China
| | - T Wang
- The First People,s Hospital of Lian Yun Gang, Lianyungang, China
| | - X Li
- Shanghai Skin Disease Hospital Clinical School of Anhui Medical University, Shanghai, China.,Skin & Cosmetic Research Department, Shanghai Skin Disease Hospital, Shanghai, China
| | - Y Ma
- Dermatological Department, Affiliated Hospital of Xuzhou Medical College, Xuzhou, China
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Zaelzer C, Hua P, Prager-Khoutorsky M, Ciura S, Voisin D, Liedtke W, Bourque C. ΔN-TRPV1: A Molecular Co-detector of Body Temperature and Osmotic Stress. Cell Rep 2015; 13:23-30. [DOI: 10.1016/j.celrep.2015.08.061] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 07/25/2015] [Accepted: 08/21/2015] [Indexed: 10/23/2022] Open
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Is the experience of thermal pain genetics dependent? BIOMED RESEARCH INTERNATIONAL 2015; 2015:349584. [PMID: 25699274 PMCID: PMC4324494 DOI: 10.1155/2015/349584] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 11/10/2014] [Accepted: 11/10/2014] [Indexed: 01/06/2023]
Abstract
It is suggested that genetic variations explain a significant portion of the variability in pain perception; therefore, increased understanding of pain-related genetic influences may identify new targets for therapies and treatments. The relative contribution of the different genes to the variance in clinical and experimental pain responses remains unknown. It is suggested that the genetic contributions to pain perception vary across pain modalities. For example, it has been suggested that more than 60% of the variance in cold pressor responses can be explained by genetic factors; in comparison, only 26% of the variance in heat pain responses is explained by these variations. Thus, the selection of pain model might markedly influence the magnitude of the association between the pain phenotype and genetic variability. Thermal pain sensation is complex with multiple molecular and cellular mechanisms operating alone and in combination within the peripheral and central nervous system. It is thus highly probable that the thermal pain experience is affected by genetic variants in one or more of the pathways involved in the thermal pain signaling. This review aims to present and discuss some of the genetic variations that have previously been associated with different experimental thermal pain models.
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Abstract
TRPV1 is a well-characterised channel expressed by a subset of peripheral sensory neurons involved in pain sensation and also at a number of other neuronal and non-neuronal sites in the mammalian body. Functionally, TRPV1 acts as a sensor for noxious heat (greater than ~42 °C). It can also be activated by some endogenous lipid-derived molecules, acidic solutions (pH < 6.5) and some pungent chemicals and food ingredients such as capsaicin, as well as by toxins such as resiniferatoxin and vanillotoxins. Structurally, TRPV1 subunits have six transmembrane (TM) domains with intracellular N- (containing 6 ankyrin-like repeats) and C-termini and a pore region between TM5 and TM6 containing sites that are important for channel activation and ion selectivity. The N- and C- termini have residues and regions that are sites for phosphorylation/dephosphorylation and PI(4,5)P2 binding, which regulate TRPV1 sensitivity and membrane insertion. The channel has several interacting proteins, some of which (e.g. AKAP79/150) are important for TRPV1 phosphorylation. Four TRPV1 subunits form a non-selective, outwardly rectifying ion channel permeable to monovalent and divalent cations with a single-channel conductance of 50-100 pS. TRPV1 channel kinetics reveal multiple open and closed states, and several models for channel activation by voltage, ligand binding and temperature have been proposed. Studies with TRPV1 agonists and antagonists and Trpv1 (-/-) mice have suggested a role for TRPV1 in pain, thermoregulation and osmoregulation, as well as in cough and overactive bladder. TRPV1 antagonists have advanced to clinical trials where findings of drug-induced hyperthermia and loss of heat sensitivity have raised questions about the viability of this therapeutic approach.
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Mistry S, Paule CC, Varga A, Photiou A, Jenes A, Avelino A, Buluwela L, Nagy I. Prolonged exposure to bradykinin and prostaglandin E2 increases TRPV1 mRNA but does not alter TRPV1 and TRPV1b protein expression in cultured rat primary sensory neurons. Neurosci Lett 2014; 564:89-93. [PMID: 24525250 DOI: 10.1016/j.neulet.2014.02.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 01/22/2014] [Accepted: 02/03/2014] [Indexed: 01/18/2023]
Abstract
Sensitisation of the capsaicin receptor, transient receptor potential vanilloid type 1 (TRPV1) ion channel in nociceptive primary sensory neurons (PSN) underlies the development of inflammatory heat hyperalgesia. Removal of the negative-dominant splice variant of the TRPV1 molecule, TRPV1b from TRPV1/TRPV1b heterotetrameric channels, which should be associated with changes in the expression of TRPV1 and TRPV1b transcripts and proteins, has been suggested to contribute to that sensitisation. Respective reverse-transcriptase polymerase chain reaction (RT-PCR) and Western-blotting revealed that both TRPV1 and TRPV1b mRNA, and their encoded proteins are expressed in rat cultured PSN. Sequencing of the RT-PCR products showed that TRPV1b mRNA lacks the entire exon 7. Further, growing PSN for 2 days in the presence of 10μM bradykinin (BK) and 10μM prostaglandin E2 (PGE2) significantly increases TRPV1 responsiveness and TRPV1 mRNA expression, without producing any changes in TRPV1b mRNA, and TRPV1 and TRPV1b protein expression. These data challenge the hypothesis that alterations in the composition of the TRPV1 ion channel contributes to the sensitisation.
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Affiliation(s)
- Shilpa Mistry
- Section of Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer, Imperial College London, Chelsea and Westminster Hospital, 369 Fulham Road. London, SW10 9NH, United Kingdom
| | - Cleoper C Paule
- Section of Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer, Imperial College London, Chelsea and Westminster Hospital, 369 Fulham Road. London, SW10 9NH, United Kingdom
| | - Angelika Varga
- Section of Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer, Imperial College London, Chelsea and Westminster Hospital, 369 Fulham Road. London, SW10 9NH, United Kingdom
| | - Andy Photiou
- Division of Oncology, Department of Surgery and Cancer Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, United Kingdom
| | - Agnes Jenes
- Section of Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer, Imperial College London, Chelsea and Westminster Hospital, 369 Fulham Road. London, SW10 9NH, United Kingdom; Department of Physiology, University of Debrecen, Medical and Health Science Centre, Nagyerdei krt. 98, Debrecen, H-4012, Hungary
| | - Antonio Avelino
- Department of Experimental Biology, Faculty of Medicine, Alameda Prof. Hernani Monteiro, 4200-319, Porto, Portugal; IBMC, University of Porto, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal
| | - Laki Buluwela
- Division of Oncology, Department of Surgery and Cancer Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, United Kingdom
| | - Istvan Nagy
- Section of Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer, Imperial College London, Chelsea and Westminster Hospital, 369 Fulham Road. London, SW10 9NH, United Kingdom.
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Lötsch J, Ultsch A. A machine-learned knowledge discovery method for associating complex phenotypes with complex genotypes. Application to pain. J Biomed Inform 2013; 46:921-8. [DOI: 10.1016/j.jbi.2013.07.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 07/16/2013] [Accepted: 07/18/2013] [Indexed: 10/26/2022]
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Buckinx R, Van Nassauw L, Avula LR, Alpaerts K, Adriaensen D, Timmermans JP. Transient receptor potential vanilloid type 1 channel (TRPV1) immunolocalization in the murine enteric nervous system is affected by the targeted C-terminal epitope of the applied antibody. J Histochem Cytochem 2013; 61:421-32. [PMID: 23482327 DOI: 10.1369/0022155413484764] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The expression of transient receptor potential vanilloid type 1 channel (TRPV1) in the enteric nervous system is still the subject of debate. Although a number of studies have reported that TRPV1 is limited to extrinsic afferent fibers, other studies argue for an intrinsic expression of TRPV1. In the present study, reverse transcriptase PCR was employed to establish the expression of TRPV1 mRNA throughout the gastrointestinal tract. Using two antibodies directed against different epitopes of TRPV1, we were able to show at the protein level that the observed distribution pattern of TRPV1 is dependent on the antibody used in the immunohistochemical staining. A first antibody indeed mainly stained neuronal fibers, whereas a second antibody exclusively stained perikarya of enteric neurons throughout the mouse gastrointestinal tract. We argue that these different distribution patterns are due to the antibodies discriminating between different modulated forms of TRPV1 that influence the recognition of the targeted immunogen and as such distinguish intracellular from plasmalemmal forms of TRPV1. Our study is the first to directly compare these two antibodies within the same species and in identical conditions. Our observations underline that detailed knowledge of the epitope that is recognized by the antibodies employed in immunohistochemical procedures is a prerequisite for correctly interpreting experimental results.
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Affiliation(s)
- Roeland Buckinx
- Laboratory of Cell Biology and Histology, Department of Veterinary Sciences, University of Antwerp, Antwerp, Belgium
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Nishihara E, Hiyama TY, Noda M. Osmosensitivity of transient receptor potential vanilloid 1 is synergistically enhanced by distinct activating stimuli such as temperature and protons. PLoS One 2011; 6:e22246. [PMID: 21779403 PMCID: PMC3136519 DOI: 10.1371/journal.pone.0022246] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 06/17/2011] [Indexed: 11/25/2022] Open
Abstract
In animals, body-fluid osmolality is continuously monitored to keep it within a narrow range around a set point (∼300 mOsm/kg). Transient receptor potential vanilloid 1 (TRPV1), a cation channel, has been implicated in body-fluid homeostasis in vivo based on studies with the TRPV1-knockout mouse. However, the response of TRPV1 to hypertonic stimuli has not been demonstrated with heterologous expression systems so far, despite intense efforts by several groups. Thus, the molecular entity of the hypertonic sensor in vivo still remains controversial. Here we found that the full-length form of TRPV1 is sensitive to an osmotic increase exclusively at around body temperature using HEK293 cells stably expressing rat TRPV1. At an ambient temperature of 24°C, a slight increase in the intracellular calcium concentration ([Ca(2+)](i)) was rarely observed in response to hypertonic stimuli. However, the magnitude of the osmosensitive response markedly increased with temperature, peaking at around 36°C. Importantly, the response at 36°C showed a robust increase over a hypertonic range, but a small decrease over a hypotonic range. A TRPV1 antagonist, capsazepine, and a nonspecific TRP channel inhibitor, ruthenium red, completely blocked the increase in [Ca(2+)](i). These results endorse the view that the full-length form of TRPV1 is able to function as a sensor of hypertonic stimuli in vivo. Furthermore, we found that protons and capsaicin likewise synergistically potentiated the response of TRPV1 to hypertonic stimuli. Of note, HgCl(2), which blocks aquaporins and inhibits cell-volume changes, significantly reduced the osmosensitive response. Our findings thus indicate that TRPV1 integrates multiple different types of activating stimuli, and that TRPV1 is sensitive to hypertonic stimuli under physiologically relevant conditions.
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Affiliation(s)
- Eri Nishihara
- Division of Molecular Neurobiology, National Institute for Basic Biology, The Graduate University for Advanced Studies, Okazaki, Aichi, Japan
| | - Takeshi Y. Hiyama
- Division of Molecular Neurobiology, National Institute for Basic Biology, The Graduate University for Advanced Studies, Okazaki, Aichi, Japan
- School of Life Science, The Graduate University for Advanced Studies, Okazaki, Aichi, Japan
| | - Masaharu Noda
- Division of Molecular Neurobiology, National Institute for Basic Biology, The Graduate University for Advanced Studies, Okazaki, Aichi, Japan
- School of Life Science, The Graduate University for Advanced Studies, Okazaki, Aichi, Japan
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Schumacher MA, Eilers H. TRPV1 splice variants: structure and function. Front Biosci (Landmark Ed) 2010; 15:872-82. [PMID: 20515731 DOI: 10.2741/3651] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The capsaicin receptor (TRPV1) is a non-selective cation channel predominantly expressed in specialized sensory neurons that detect painful stimuli. Although its many functional roles continue to be revealed, it has been confirmed to play a critical role in the perception of peripheral inflammatory hyperalgesia and pain. TRPV1 not only is sensitized and/or activated under a wide range of conditions including inflammation and nerve injury but also undergoes changes in expressed levels in response to these same pathologic conditions. Just as our understanding of the structural requirements of TRPV1 activation has grown, there is evidence that TRPV1 forms heteromeric channel complexes. This review is focused on the structural and functional consequence of TRPV1 splice variants: VR.5'sv, TRPV1b/beta and TRPV1var. Through their co-expression and formation of heteromeric complexes with TRPV1, they have been shown to modulate TRPV1 activation. Moreover, TRPV1 splice variant subunits may also contribute unique properties of activation such as the detection of hypertonic conditions.
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Affiliation(s)
- Mark A Schumacher
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, CA 94143-0427, USA.
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Bianchi BR, El Kouhen R, Chen J, Puttfarcken PS. Binding of [3H]A-778317 to native transient receptor potential vanilloid-1 (TRPV1) channels in rat dorsal root ganglia and spinal cord. Eur J Pharmacol 2010; 633:15-23. [DOI: 10.1016/j.ejphar.2010.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Revised: 12/04/2009] [Accepted: 02/02/2010] [Indexed: 01/13/2023]
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van Esch AAJ, Lamberts MP, te Morsche RHM, van Oijen MGH, Jansen JBMJ, Drenth JPH. Polymorphisms in gene encoding TRPV1-receptor involved in pain perception are unrelated to chronic pancreatitis. BMC Gastroenterol 2009; 9:97. [PMID: 20034385 PMCID: PMC2813232 DOI: 10.1186/1471-230x-9-97] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Accepted: 12/24/2009] [Indexed: 11/10/2022] Open
Abstract
Background The major clinical feature in chronic pancreatitis is pain, but the genetic basis of pancreatic pain in chronic pancreatitis is poorly understood. The transient receptor potential vanilloid receptor 1 (TRPV1) gene has been associated with pain perception, and genetic variations in TRPV1 may modify the presence and phenotype of chronic pancreatitis. The aim of our study was to investigate the genetic variation of TRPV1 in Dutch patients with chronic pancreatitis and healthy controls. Methods We genotyped 4 SNPs (rs222749, rs222747, rs224534 and rs8065080) in 228 chronic pancreatitis-patients and 207 healthy controls by PCR, followed by restriction-fragment-length-polymorphism analysis and DNA sequencing. We generated 27 diplotypes and compared prevalence between patients and controls. Results There was no significant difference in allele frequency of the 4 TRPV1 gene SNPs in patients with chronic pancreatitis and healthy controls. Distribution of diplotypes was not statistically significantly different between patients and controls. Conclusion TRPV1 diplotypes are not associated with chronic pancreatitis.
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Affiliation(s)
- Aura A J van Esch
- Department of Gastroenterology & Hepatology, Radboud University Nijmegen Medical Centre, The Netherlands.
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17
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Is thermal nociception only sensed by the capsaicin receptor, TRPV1? Anat Sci Int 2009; 84:122-8. [PMID: 19562439 DOI: 10.1007/s12565-009-0048-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2008] [Accepted: 05/14/2009] [Indexed: 02/03/2023]
Abstract
Mammalian heat pain perception is well documented as a molecular event in the primary afferent neurons expressing TRPV1. Six types of thermo-TRPs were found, i.e., TRPV1-4, TRPM8 and TRPA1. The former TRPV1, 2 and TRPV3, 4 are sensitive to noxious heat and warmth, and the latter two are sensitive to cool or cold, respectively. We attempted to provide a hypothesis to explain the paradox in which TRPV1 knockout mice and capsaicin-pretreated mice with severe loss of small dorsal root ganglion (DRG) neurons behave normally to noxious heat. From the general view that TRPV1 is preferentially expressed in C-fibers responding to a moderate thermal threshold (>43 degrees C) and TRPV2 in Adelta-fibers to high threshold temperatures (>52 degrees C), the above phenomenon is perplexing. Woodbury et al. (J Neurosci 24:6410-6415, 2004) offered two pain transduction mechanisms, one being TRPV1/2-independent and the other TRPV1-dependent. The former detects noxious heat under normal conditions without the presence of TRPV1 or TRPV2, and the latter requires TRPV1 under pathophysiological conditions. Unidentified isolectin B4 (IB4)-positive but TRPV1-negative small neurons with a higher noxious heat threshold are feasible, because a spliced isoform of TRPV1 responsive to noxious heat (47 degrees C) but not responsive to either proton or capsaicin is present in human and rat sensory neurons. Thus, the IB4-positive but TRPV1-negative small sensory neurons must have a crucial role in the noxious heat response.
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Abstract
OBJECTIVE In this review, we explain our current understanding of the molecular basis for pain relief by capsaicin and other transient receptor potential vanilloid subfamily, member 1 (TRPV1) agonists. We summarize disease-related changes in TRPV1 expression and its implications for therapy and potential adverse effects. Last, we provide an overview of the current clinical uses of topical and injectable TRPV1 agonist preparations in both oncologic and nononcologic populations. METHOD Search of MEDLINE and other databases. RESULTS The capsaicin receptor TRPV1 is a polymodal nociceptor exhibiting a dynamic threshold of activation that could be lowered under inflammatory conditions. Consistent with this model, TRPV1 knock-out mice are devoid of post-inflammatory thermal hyperalgesia. TRPV1 desensitization of primary sensory neurons is a powerful approach to relieve symptoms of nociceptive behavior in animal models of chronic pain. However, over-the-counter capsaicin creams have shown moderate to poor analgesic efficacy. This is in part related to low dose, poor skin absorption, and compliance factors. Recently developed site-specific capsaicin therapy with high-dose patches and injectable preparations seem to be safe and reportedly provide long-lasting analgesia with rapid onset. CONCLUSIONS We argue that TRPV1 agonists and antagonists are not mutually exclusive but rather complimentary pharmacologic approaches for pain relief and we predict a "revival" for capsaicin and other TRPV1 agonists in the clinical management of pain associated with inflammation, metabolic imbalances (eg, diabetes), infections (HIV), and cancer, despite the current focus of the pharmaceutical industry on TRPV1 antagonists.
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Eilers H, Lee SY, Hau CW, Logvinova A, Schumacher MA. The rat vanilloid receptor splice variant VR.5'sv blocks TRPV1 activation. Neuroreport 2007; 18:969-73. [PMID: 17558279 DOI: 10.1097/wnr.0b013e328165d1a2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The capsaicin receptor (VR1, TRPV1) is a ligand-gated ion channel predominantly expressed in peripheral nociceptors and activated by multiple noxious stimuli including products of inflammation. A 5'-splice variant (VR.5'sv) of TRPV1 has been previously isolated and found to be insensitive to noxious stimuli. We report in this study that coexpression of VR.5'sv with TRPV1 in Xenopus oocytes blocks TRPV1-mediated current responses. Oocytes expressing the inhibitory profile demonstrated colocalization of TRPV1 and VR.5'sv-associated immunostaining in the plasma membrane. TRPV1 protein expression was comparable in all groups. Evidence of endogenous VR.5'-splice variant-like-protein expression was detected in dorsal root ganglion. These results support the idea that coexpression of VR.5'sv or a similar variant could result in inhibitory modulation of TRPV1 activation.
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Affiliation(s)
- Helge Eilers
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, California 94143-0427, USA
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20
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Frederick J, Buck ME, Matson DJ, Cortright DN. Increased TRPA1, TRPM8, and TRPV2 expression in dorsal root ganglia by nerve injury. Biochem Biophys Res Commun 2007; 358:1058-64. [PMID: 17517374 DOI: 10.1016/j.bbrc.2007.05.029] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Accepted: 05/05/2007] [Indexed: 01/06/2023]
Abstract
Thermosensitive TRP channels display unique thermal responses, suggesting distinct roles mediating sensory transmission of temperature. However, whether relative expression of these channels in dorsal root ganglia (DRG) is altered in nerve injury is unknown. We developed a multiplex ribonuclease protection assay (RPA) to quantify rat TRPV1, TRPV2, TRPV3, TRPV4, TRPA1, and TRPM8 RNA levels in DRG. We used the multiplex RPA to measure thermosensitive TRP channel RNA levels in DRG from RTX-treated rats (300 microg/kg) or rats with unilateral sciatic nerve chronic constriction injury (CCI). TRPV1 and TRPA1 RNA were significantly decreased in DRG from RTX-treated rats, indicating functional colocalization of TRPA1 and TRPV1 in sensory nociceptors. In DRG from CCI rats, TRPA1, TRPV2, and TRPM8 RNA showed slight but significant increases ipsilateral to peripheral nerve injury. Our findings support the hypothesis that increased TRP channel expression in sensory neurons may contribute to mechanical and cold hypersensitivity.
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Affiliation(s)
- J Frederick
- Western Connecticut State University, 181 White Street, Danbury, CT 06810, USA.
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21
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Szallasi A, Cortright DN, Blum CA, Eid SR. The vanilloid receptor TRPV1: 10 years from channel cloning to antagonist proof-of-concept. Nat Rev Drug Discov 2007; 6:357-72. [PMID: 17464295 DOI: 10.1038/nrd2280] [Citation(s) in RCA: 627] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The clinical use of TRPV1 (transient receptor potential vanilloid subfamily, member 1; also known as VR1) antagonists is based on the concept that endogenous agonists acting on TRPV1 might provide a major contribution to certain pain conditions. Indeed, a number of small-molecule TRPV1 antagonists are already undergoing Phase I/II clinical trials for the indications of chronic inflammatory pain and migraine. Moreover, animal models suggest a therapeutic value for TRPV1 antagonists in the treatment of other types of pain, including pain from cancer. We argue that TRPV1 antagonists alone or in conjunction with other analgesics will improve the quality of life of people with migraine, chronic intractable pain secondary to cancer, AIDS or diabetes. Moreover, emerging data indicate that TRPV1 antagonists could also be useful in treating disorders other than pain, such as urinary urge incontinence, chronic cough and irritable bowel syndrome. The lack of effective drugs for treating many of these conditions highlights the need for further investigation into the therapeutic potential of TRPV1 antagonists.
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Affiliation(s)
- Arpad Szallasi
- Department of Pathology, Monmouth Medical Center, Long Branch, New Jersey 07740, USA.
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22
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Vos MH, Neelands TR, McDonald HA, Choi W, Kroeger PE, Puttfarcken PS, Faltynek CR, Moreland RB, Han P. TRPV1b overexpression negatively regulates TRPV1 responsiveness to capsaicin, heat and low pH in HEK293 cells. J Neurochem 2007; 99:1088-102. [PMID: 17018028 DOI: 10.1111/j.1471-4159.2006.04145.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Transient receptor potential channel type V (TRPV) 1 is a non-selective cation channel that can be activated by capsaicin, endogenous vanilloids, heat and protons. The human TRPV1 splice variant, TRPV1b, lacking exon 7, was cloned from human dorsal root ganglia (DRG) RNA. The expression profile and relative abundance of TRPV1b and TRPV1 in 35 different human tissues were determined by quantitative RT-PCR using isoform-specific probes. TRPV1b was most abundant in fetal brain, adult cerebellum and DRG. Functional studies using electrophysiological techniques showed that recombinant TRPV1b was not activated by capsaicin (1 microM), protons (pH 5.0) or heat (50 degrees C). However, recombinant TRPV1b did form multimeric complexes and was detected on the plasma membrane of cells, demonstrating that the lack of channel function was not due to defects in complex formation or cell surface expression. These results demonstrate that exon 7, which encodes the third ankyrin domain and 44 amino acids thereafter, is required for normal channel function of human TRPV1. Moreover, when co-expressed with TRPV1, TRPV1b formed complexes with TRPV1, and inhibited TRPV1 channel function in response to capsaicin, acidic pH, heat and endogenous vanilloids, dose-dependently. Taken together, these data support the hypothesis that TRPV1b is a naturally existing inhibitory modulator of TRPV1.
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Affiliation(s)
- Melissa H Vos
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064, USA
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23
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Park JJ, Lee J, Kim MA, Back SK, Hong SK, Na HS. Induction of total insensitivity to capsaicin and hypersensitivity to garlic extract in human by decreased expression of TRPV1. Neurosci Lett 2007; 411:87-91. [PMID: 17110039 DOI: 10.1016/j.neulet.2006.10.046] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Revised: 10/27/2006] [Accepted: 10/27/2006] [Indexed: 10/23/2022]
Abstract
TRPV1 is a cation channel which is activated by temperature (> or =42 degrees C) and capsaicin. In the present study, we found a person with total insensitivity to capsaicin and attempted to unravel its causes. The expression levels of TRPV1 protein and mRNA in the cells of the person's buccal mucosa were less than half of those in a normal subject. Sequential analysis of mRNA and genomic DNA revealed several point mutations mostly in the second intron of the person's TRPV1. Interestingly, the subject showed hypersensitivity to garlic extract, but TRPA1 (allicin receptor) level was normal. These results suggest that the decreased expression of TRPV1 may be related to a functional knock out in capsaicin sensation and hypersensitivity to allicin in humans.
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Affiliation(s)
- Joong Jean Park
- Department of Physiology, College of Medicine, Korea University, 126-1 Anam-Dong 5 Ga, Sungbuk-Gu, Seoul 136-705, Republic of Korea
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24
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Abstract
Ion channel functional diversity can be achieved at the structural level by means of three main mechanisms: (1) transcriptional regulation and processing of mRNA, (2) heteromerization of different pore-forming channel subunits and (3) incorporation of regulatory subunits to the functional channel complex. In this review article we will focus on one of these mechanisms, alternative pre-mRNA splicing, in the context of the TRP superfamily of cation channels. For this purpose, the basic principles governing pre-mRNA splicing will be introduced and comprehensive tables classifying only published spliced-variants of TRP channels will be presented.
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Affiliation(s)
- Esther Vázquez
- Molecular Physiology and Channelopathies Group, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, C/Dr. Aiguader 80, Barcelona 08003, Spain
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25
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Xue Q, Jong B, Chen T, Schumacher MA. Transcription of rat TRPV1 utilizes a dual promoter system that is positively regulated by nerve growth factor. J Neurochem 2006; 101:212-22. [PMID: 17217411 DOI: 10.1111/j.1471-4159.2006.04363.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The capsaicin receptor, also known as 'transient receptor potential vanilloid receptor subtype 1' (TRPV1, VR1), is an ion channel subunit expressed in primary afferent nociceptors, which plays a critical role in pain transduction and thermal hyperalgesia. Increases in nociceptor TRPV1 mRNA and protein are associated with tissue injury-inflammation. As little is understood about what controls TRPV1 RNA transcription in nociceptors, we functionally characterized the upstream portion of the rat TRPV1 gene. Two functional rTRPV1 promoter regions and their transcription initiation sites were identified. Although both promoter regions directed transcriptional activity in nerve growth factor (NGF) treated rat sensory neurons, the upstream Core promoter was the most active in cultures enriched in sensory neurons. Because NGF is a key modulator of inflammatory pain, we examined the effect of NGF on rTRPV1 transcription in PC12 cells. NGF positively regulated transcriptional activity of both rTRPV1 promoter regions in PC12 cells. We propose that the upstream regulatory region of the rTRPV1 gene is composed of a dual promoter system that is regulated by NGF. These findings support the hypothesis that NGF produced under conditions of tissue injury and/or inflammation directs an increase of TRPV1 expression in nociceptors in part through a transcription-dependent mechanism.
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Affiliation(s)
- Qing Xue
- Department of Anesthesia and Perioperative Care, University of California San Francisco, San Francisco, California 94143-0427, USA
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26
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Rosenbaum T, Simon S. TRPV1 Receptors and Signal Transduction. TRP ION CHANNEL FUNCTION IN SENSORY TRANSDUCTION AND CELLULAR SIGNALING CASCADES 2006. [DOI: 10.1201/9781420005844.ch5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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27
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Sharif Naeini R, Witty MF, Séguéla P, Bourque CW. An N-terminal variant of Trpv1 channel is required for osmosensory transduction. Nat Neurosci 2005; 9:93-8. [PMID: 16327782 DOI: 10.1038/nn1614] [Citation(s) in RCA: 230] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Accepted: 11/14/2005] [Indexed: 11/09/2022]
Abstract
Body fluid homeostasis requires the release of arginine-vasopressin (AVP, an antidiuretic hormone) from the neurohypophysis. This release is controlled by specific and highly sensitive 'osmoreceptors' in the hypothalamus. Indeed, AVP-releasing neurons in the supraoptic nucleus (SON) are directly osmosensitive, and this osmosensitivity is mediated by stretch-inhibited cation channels. However, the molecular nature of these channels remains unknown. Here we show that SON neurons express an N-terminal splice variant of the transient receptor potential vanilloid type-1 (Trpv1), also known as the capsaicin receptor, but not full-length Trpv1. Unlike their wild-type counterparts, SON neurons in Trpv1 knockout (Trpv1(-/-)) mice could not generate ruthenium red-sensitive increases in membrane conductance and depolarizing potentials in response to hyperosmotic stimulation. Moreover, Trpv1(-/-) mice showed a pronounced serum hyperosmolality under basal conditions and severely compromised AVP responses to osmotic stimulation in vivo. These results suggest that the Trpv1 gene may encode a central component of the osmoreceptor.
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Affiliation(s)
- Reza Sharif Naeini
- Centre for Research in Neuroscience, McGill University, 1650 Cedar Avenue, Montreal, Quebec H3G 1A4, Canada
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28
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Abstract
In recent years many new members of the family of TRP ion channels have been identified. These channels are classified into several subgroups and participate in many sensory and physiological functions. TRPV channels are important for the perception of pain, temperature sensing, osmotic regulation, and maintenance of calcium homeostasis, and much recent research concerns the identification of protein domains involved in mediating specific channel functions. Recent literature on TRPV channel subunit composition, protein domains required for subunit assembly, trafficking, and regulation will be reviewed and discussed.
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Affiliation(s)
- Barbara A Niemeyer
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, Gebäude 46, 66421, Homburg, Germany.
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29
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Tian W, Fu Y, Wang DH, Cohen DM. Regulation of TRPV1 by a novel renally expressed rat TRPV1 splice variant. Am J Physiol Renal Physiol 2005; 290:F117-26. [PMID: 16091583 DOI: 10.1152/ajprenal.00143.2005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The capsaicin receptor and transient receptor potential channel TRPV1 senses heat, protons, and vanilloid agonists in peripheral sensory ganglia. Abundant data have suggested the presence of potentially novel splice variants in the kidney. We report a novel rat TRPV1 splice variant, TRPV1(VAR), cloned from kidney papilla. TRPV1(VAR) cDNA was identified in multiple kidney tissues. Its sequence was fully compatible with potential splice donor and acceptor sites in the rat TRPV1 gene. TRPV1(VAR) is predicted to encode a truncated form of TRPV1 consisting of the NH2-terminal 248 residues of TRPV1 (all within the NH2-terminal intracellular domain) followed by five nonconsensus amino acids (Arg-Glu-Ala-Met-Trp) and a stop codon. The variant utilizes the same consensus Kozak sequence as canonical TRPV1. A band of the appropriate molecular mass was identified in rat kidney papillary (but not medullary) lysates immunoblotted with an antibody directed against the NH2 terminus of TRPV1, whereas an antibody recognizing the TRPV1 COOH terminus failed to detect it. Upon heterologous expression in HEK 293 cells, TRPV1(VAR) potentiated the ability of cotransfected TRPV1 to confer calcium influx in response to resiniferatoxin. TRPV1(VAR) did not influence expression or cell surface localization of cotransfected TRPV1. TRPV1(VAR) protein product associated with the NH2 terminus of canonical TRPV1. Interestingly, when expressed in the COS-7 epithelial cell line, TRPV1(VAR) functioned in a dominant-negative acting capacity, partially blocking TRPV1-dependent resiniferatoxin responsiveness. We conclude that TRPV1(VAR) is one of perhaps several TRPV1 splice variants expressed in rat kidney and that it may serve to modulate TRPV1 responsiveness in some tissues.
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Affiliation(s)
- Wei Tian
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University and the Portland Veterans Affairs Medical Center, Portland, OR 97239, USA
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30
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Lis A, Wissenbach U, Philipp SE. Transcriptional regulation and processing increase the functional variability of TRPM channels. Naunyn Schmiedebergs Arch Pharmacol 2005; 371:315-24. [PMID: 15856355 DOI: 10.1007/s00210-005-1050-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2004] [Accepted: 02/19/2005] [Indexed: 12/14/2022]
Abstract
Mammalian TRP channels display heterogenous biophysical properties and are involved in a variety of signal transduction pathways. To carry out their diverse biological functions and to adapt these functions to changes of the environment, mechanisms to regulate their molecular structure are required. Transcriptional regulation and post-transcriptional RNA processing represent essential instruments to generate TRP channel variants with modified properties. TRP variants are expressed depending on the tissue and developmental state. They can show distinct biophysical properties and mechanisms of activation, and thereby determine channel function and malfunction in certain human diseases. In this review, we give an overview of the variants of a given TRP gene, with the focus on the TRPM subfamily, and discuss their relevance with respect to their function under physiological and pathological conditions.
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Affiliation(s)
- Annette Lis
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Medizinische Fakultät, Universität des Saarlandes, 66421, Homburg, Germany
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Lu G, Henderson D, Liu L, Reinhart PH, Simon SA. TRPV1b, a functional human vanilloid receptor splice variant. Mol Pharmacol 2005; 67:1119-27. [PMID: 15644492 DOI: 10.1124/mol.104.009852] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Transient receptor potential (TRP) genes encode a family of related ion-channel subunits. This family consists of cation-selective, calcium-permeable channels that include a group of vanilloid receptor channels (TRPV) implicated in pain and inflammation. These channels are activated by diverse stimuli, including capsaicin, lipids, membrane deformation, heat, and protons. Six members of the TRPV family have been identified that differ predominantly in their activation properties. However, in neurons, TRPV channels do not account for the observed diversity of responses to activators. By probing human and rat brain cDNA libraries to identify TRPV subunits, we identified a novel human TRPV1 RNA splice variant, TRPV1b, which forms functional ion channels that are activated by temperature (threshold, approximately 47 degrees C), but not by capsaicin or protons. Channels with similar activation properties were found in trigeminal ganglion neurons, suggesting that TRPV1b receptors are expressed in these cells and contribute to thermal nociception.
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Affiliation(s)
- Gang Lu
- Box 3209, Duke University Medical Center, Durham, NC 27710, USA
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Trevisani M, Milan A, Gatti R, Zanasi A, Harrison S, Fontana G, Morice AH, Geppetti P. Antitussive activity of iodo-resiniferatoxin in guinea pigs. Thorax 2004; 59:769-72. [PMID: 15333853 PMCID: PMC1747129 DOI: 10.1136/thx.2003.012930] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Iodo-resiniferatoxin (I-RTX) has recently been described as an ultra potent antagonist of the transient receptor potential vanilloid-1 (TRPV1). METHODS The ability of I-RTX to inhibit cough induced by inhalation of two putative TRPV1 stimulants (capsaicin and citric acid) was tested in non-anaesthetised guinea pigs. RESULTS Pretreatment with I-RTX either intraperitoneally (0.03-0.3 micromol/kg) or by aerosol (0.1-3 microM) reduced the number of coughs produced by inhalation of citric acid (0.25 M) and capsaicin (30 microM) in a dose dependent manner. Capsazepine (CPZ) also reduced citric acid and capsaicin induced cough, but the activity of I-RTX was 10-100 times more potent than CPZ in all the experimental conditions tested. CONCLUSIONS I-RTX is a novel and potent antitussive drug which inhibits cough mediated by agents possibly acting via TRPV1 activation.
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Affiliation(s)
- M Trevisani
- Center of Excellence for the Study of Inflammation, University of Ferrara, Ferrara, Italy.
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Ferrer-Montiel A, García-Martínez C, Morenilla-Palao C, García-Sanz N, Fernández-Carvajal A, Fernández-Ballester G, Planells-Cases R. Molecular architecture of the vanilloid receptor. Insights for drug design. ACTA ACUST UNITED AC 2004; 271:1820-6. [PMID: 15128292 DOI: 10.1111/j.1432-1033.2004.04083.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The transient receptor potential channel vanilloid receptor subunit 1 (TRPV1) is a molecular integrator of physical and chemical stimuli in the peripheral nociceptor terminals. TRPV1 is an ionotropic channel that plays a critical role in both thermal nociception and inflammatory hyperalgesia. Structure-function relationships are providing fundamental insights of the modular architecture of this neuronal receptor. As a result, the molecular determinants that endow TRPV1 with its physiological properties, namely activation by heat, potentiation by extracellular acidic pH, and interaction with vanilloid-like compounds, as well as its permeation properties are being unveiled. This information can now be used to build up molecular models for the protein which, upon experimental validation, could be used as tools to thrust the target-oriented design of druggable TRPV1 ligands.
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Affiliation(s)
- Antonio Ferrer-Montiel
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Alicante, Spain.
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Wang C, Hu HZ, Colton CK, Wood JD, Zhu MX. An alternative splicing product of the murine trpv1 gene dominant negatively modulates the activity of TRPV1 channels. J Biol Chem 2004; 279:37423-30. [PMID: 15234965 DOI: 10.1074/jbc.m407205200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Transient receptor potential vanilloid 1 (TRPV1), or vanilloid receptor 1, is the founding member of the vanilloid type of TRP superfamily of nonselective cation channels. TRPV1 is activated by noxious heat, acid, and alkaloid irritants as well as several endogenous ligands and is sensitized by inflammatory factors, thereby serving important functions in detecting noxious stimuli in the sensory system and pathological states in different parts of the body. Whereas numerous studies have been carried out using the rat and human TRPV1 cDNA, the mouse TRPV1 cDNA has not been characterized. Here, we report molecular cloning of two TRPV1 cDNA variants from dorsal root ganglia of C57BL/6 mice. The deduced proteins are designated TRPV1alpha and TRPV1beta and contain 839 and 829 amino acids, respectively. TRPV1beta arises from an alternative intron recognition signal within exon 7 of the trpv1 gene. We found a predominant expression of TRPV1alpha in many tissues and significant expression of TRPV1beta in dorsal root ganglia, skin, stomach, and tongue. When expressed in HEK 293 cells or Xenopus oocytes, TRPV1alpha formed a Ca(2+)-permeable channel activated by ligands known to stimulate TRPV1. TRPV1beta was not functional by itself but its co-expression inhibited the function of TRPV1alpha. Furthermore, although both isoforms were synthesized at a similar rate, less TRPV1beta than TRPV1alpha protein was found in cells and on the cell surface, indicating that the beta isoform is highly unstable. Our data suggest that TRPV1beta is a naturally occurring dominant-negative regulator of the responses of sensory neurons to noxious stimuli.
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Affiliation(s)
- Chunbo Wang
- Department of Neuroscience and Center for Molecular Neurobiology, The Ohio State University, Columbus, OH 43210, USA
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35
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Abstract
The vanilloid receptor [transient receptor potential (TRP)V1, also known as VR1] is a member of the TRP channel family. These receptors share a significant sequence homology, a similar predicted structure with six transmembrane-spanning domains (S1-S6), a pore-forming region between S5 and S6, and the cytoplasmically oriented C- and N-terminal regions. Although structural/functional studies have identified some of the key amino acids influencing the gating of the TRPV1 ion channel, the possible contributions of terminal regions to vanilloid receptor function remain elusive. In the present study, C-terminal truncations of rat TRPV1 have been constructed to characterize the contribution of the cytoplasmic C-terminal region to TRPV1 function and to delineate the minimum amount of C tail necessary to form a functional channel. The truncation of 31 residues was sufficient to induce changes in functional properties of TRPV1 channel. More pronounced effects of C-terminal truncation were seen in mutants lacking the final 72 aa. These changes were characterized by a decline of capsaicin-, pH-, and heat-sensitivity; progressive reduction of the activation thermal threshold (from 41.5 to 28.6 degrees C); and slowing of the activation rate of heat-evoked membrane currents (Q10 from 25.6 to 4.7). The voltage-induced currents of the truncated mutants exhibited a slower onset, markedly reduced outward rectification, and significantly smaller peak tail current amplitudes. Truncation of the entire TRPV1 C-terminal domain (155 residues) resulted in a nonfunctional channel. These results indicate that the cytoplasmic COOH-terminal domain strongly influences the TRPV1 channel activity, and that the distal half of this structural domain confers specific thermal sensitivity.
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Wang Y, Szabo T, Welter JD, Toth A, Tran R, Lee J, Kang SU, Suh YG, Blumberg PM, Lee J. High affinity antagonists of the vanilloid receptor. Mol Pharmacol 2002; 62:947-56. [PMID: 12237342 DOI: 10.1124/mol.62.4.947] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The vanilloid receptor VR1 has attracted great interest as a sensory transducer for capsaicin, protons, and heat, and as a therapeutic target. Here we characterize two novel VR1 antagonists, KJM429 [N-(4-tert-butylbenzyl)-N'-[4-(methylsulfonylamino)benzyl]thiourea] and JYL1421 [N-(4-tert-butylbenzyl)-N'-[3-fluoro-4-(methylsulfonylamino)benzyl]thiourea], with enhanced activity compared with capsazepine on rat VR1 expressed in Chinese hamster ovary (CHO) cells. JYL1421, the more potent of the two novel antagonists, inhibited [(3)H]resiniferatoxin binding to rVR1 with an affinity of 53.5 +/- 6.5 nM and antagonized capsaicin-induced calcium uptake with an EC(50) of 9.2 +/- 1.6 nM, reflecting 25- and 60-fold greater potencies than capsazepine. Both JYL1421 and KJM429 antagonized RTX as well as capsaicin and their mechanism was competitive. The responses to JYL1421 and KJM429 differed for calcium uptake by rVR1 induced by heat or pH. JYL1421 antagonized the response to both pH 6.0 and 5.5, whereas KJM429 antagonized at pH 6.0 but was an agonist at lower pH (<5.5). For heat, JYL1421 fully antagonized and KJM429 partially antagonized. Capsazepine showed only weak antagonism for both pH and heat. Responses of rVR1 to different activators could thus be differentially affected by different ligands. In cultured dorsal root ganglion neurons, JYL1421 and KJM429 likewise behaved as antagonists for capsaicin, confirming that the antagonism is not limited to heterologous expression systems. Finally, JYL1421 and KJM429 had little or no effect on ATP-induced calcium uptake in CHO cells lacking rVR1, unlike capsazepine. We conclude that JYL1421 is a competitive antagonist of rVR1, blocking response to all three of the agonists (capsaicin, heat, and protons) with enhanced potency relative to capsazepine.
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Affiliation(s)
- Yun Wang
- National Cancer Institute, Bethesda, Maryland 20892, USA
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Peng JB, Hediger MA. A family of calcium-permeable channels in the kidney: distinct roles in renal calcium handling. Curr Opin Nephrol Hypertens 2002; 11:555-61. [PMID: 12187321 DOI: 10.1097/00041552-200209000-00012] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
PURPOSE OF REVIEW Calcium is an essential intracellular messenger and a major component of the mineral phase of the skeleton. Calcium is absorbed in the intestine and reabsorbed in the kidney. The underlying transepithelial calcium transport mechanisms play crucial roles in calcium homeostasis. In this review, we present new developments in the area of calcium transport at the apical membrane, the first step in transepithelial calcium transport. RECENT FINDINGS Recently, a group of transient receptor potential (TRP)-related calcium-permeable channels has been identified. Several of these channels serve as important epithelial calcium entry mechanisms and possibly also as osmolarity sensors. SUMMARY Calcium channels in the kidney play important roles in maintaining total body calcium homeostasis. Their dysfunction may be associated with several human diseases such as hypercaliuric nephrolithiasis, certain forms of osteoporosis, Gitelman's disease and Bartter's syndrome.
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Affiliation(s)
- Ji-Bin Peng
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
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Marinelli S, Vaughan CW, Christie MJ, Connor M. Capsaicin activation of glutamatergic synaptic transmission in the rat locus coeruleus in vitro. J Physiol 2002; 543:531-40. [PMID: 12205187 PMCID: PMC2290516 DOI: 10.1113/jphysiol.2002.022863] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The vanilloid receptor protein (VR1) is a well-characterised integrator of noxious stimuli in peripheral sensory neurones. There is evidence for the presence of VR1 in the central nervous system, but little information as to its role there. In this study we have examined the actions of agonists for VR1 receptors in the rat locus coeruleus (LC), using whole-cell patch-clamp recordings from acutely isolated neurones and neurones in slices. Superfusion with capsaicin resulted in a concentration-dependent increase in the frequency of isolated miniature excitatory postsynaptic currents (mEPSCs) in LC neurones. The mean amplitude of the mEPSCs was not affected by capsaicin. The effects of capsaicin (1 microM) were abolished by the VR1 receptor antagonists capsazepine (10 microM) and iodoresiniferatoxin (300 nM). Removal of extracellular Ca2+ abolished the capsaicin-induced increase in frequency of mEPSCs. Capsaicin superfusion had no consistent effects on evoked excitatory postsynaptic currents. Capsaicin superfusion also resulted in the release of an adrenoceptor agonist in the LC but did not affect the membrane currents of acutely isolated LC neurones. These data demonstrate that the VR1 receptor appears to be located presynaptically on afferents to the LC, and that activation of VR1 may serve to potentiate the release of glutamate and adrenaline/noradrenaline in this brain region.
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Affiliation(s)
- Silvia Marinelli
- Department of Pharmacology, The University of Sydney, Sydney, Australia
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Abstract
The cloned vanilloid (capsaicin) receptor subtype 1 (VR1) integrates multiple noxious stimuli on peripheral terminals of primary sensory neurons. The initial excitation of these neurons is followed by a lasting refractory state, traditionally termed desensitization, that has clear therapeutic potential. Capsaicin is used to relieve neuropathic pain, uremic pruritus, and bladder overactivity. The ultrapotent vanilloid resiniferatoxin, now in phase 2 clinical trials, has improved tolerability. A less recognized human exposure to high capsaicin concentrations may occur by pepper sprays used in law enforcement. Evidence is mounting that VR1 expression is not restricted to sensory neurons. From the olfactory bulb to the cerebellum, VR1-expressing neurons are present in a number of brain nuclei, where they might be activated by anandamide. VR1 presence also was demonstrated in nonneuronal tissues. These discoveries place VR1 in a much broader perspective than pain perception and enhance the potential for unforeseen side effects, especially following prolonged vanilloid therapy. The expression of VR1 is plastic and down-regulated during vanilloid therapy, which might have a pivotal role in desensitization. Good evidence suggests altered VR1 expression in various disease states. This recognition not only may provide novel insights into pathogenesis but also may prove useful in diagnosis.
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Affiliation(s)
- Arpad Szallasi
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Szallasi A, Fowler CJ. After a decade of intravesical vanilloid therapy: still more questions than answers. Lancet Neurol 2002; 1:167-72. [PMID: 12849485 DOI: 10.1016/s1474-4422(02)00072-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Vanilloid sensitivity is a functional signature of a subset of unmyelinated fibres innervating the urinary bladder. The role that these nerves have in the physiological control of storage and voiding is unclear. However, after the bladder has been disconnected by spinal injury from the pontine micturition centre, vanilloid-sensitive fibres assume a central role in the reflex emptying of the bladder that occurs at low volumes. Intravesical vanilloid (capsaicin or resiniferatoxin) administration is beneficial in this disorder by "desensitising" these nerves. Resiniferatoxin is superior to capsaicin in terms of its tolerability profile. Investigators are moving rapidly to identify the mechanisms by which desensitisation to vanilloids occurs. Vanilloids induce lasting, but fully reversible, changes in gene expression, including downregulation of the vanilloid receptor subtype 1. It is hoped that application of gene chip technologies will address the global profile of vanilloid-induced changes in gene expression and their relative contribution to desensitisation. Drugs that target signalling mechanisms that bring about these changes in gene expression have obvious therapeutic potential.
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Affiliation(s)
- Arpad Szallasi
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA.
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Gunthorpe MJ, Benham CD, Randall A, Davis JB. The diversity in the vanilloid (TRPV) receptor family of ion channels. Trends Pharmacol Sci 2002; 23:183-91. [PMID: 11931994 DOI: 10.1016/s0165-6147(02)01999-5] [Citation(s) in RCA: 371] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Following cloning of the vanilloid receptor 1 (VR1) at least four other related proteins have been identified. Together, these form a distinct subgroup of the transient receptor potential (TRP) family of ion channels. Members of the vanilloid receptor family (TRPV) are activated by a diverse range of stimuli, including heat, protons, lipids, phorbols, phosphorylation, changes in extracellular osmolarity and/or pressure, and depletion of intracellular Ca2+ stores. However, VR1 remains the only channel activated by vanilloids such as capsaicin. These channels are excellent molecular candidates to fulfil a range of sensory and/or cellular roles that are well characterized physiologically. Furthermore, as novel pharmacological targets, the vanilloid receptors have potential for the development of many future disease treatments.
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Affiliation(s)
- Martin J Gunthorpe
- Neurology-CEDD, GlaxoSmithKline, New Frontiers Science Park, Third Avenue, CM19 5AW, Harlow, UK.
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