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Leech T, Peiris M. Mucosal neuroimmune mechanisms in gastro-oesophageal reflux disease (GORD) pathogenesis. J Gastroenterol 2024; 59:165-178. [PMID: 38221552 PMCID: PMC10904498 DOI: 10.1007/s00535-023-02065-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 11/30/2023] [Indexed: 01/16/2024]
Abstract
Gastro-oesophageal reflux disease (GORD) is a chronic condition characterised by visceral pain in the distal oesophagus. The current first-line treatment for GORD is proton pump inhibitors (PPIs), however, PPIs are ineffective in a large cohort of patients and long-term use may have adverse effects. Emerging evidence suggests that nerve fibre number and location are likely to play interrelated roles in nociception in the oesophagus of GORD patients. Simultaneously, alterations in cells of the oesophageal mucosa, namely epithelial cells, mast cells, dendritic cells, and T lymphocytes, have been a focus of GORD research for several years. The oesophagus of GORD patients exhibits both macro- and micro-inflammation as a response to chronic acidic reflux at the epithelium. In other conditions of the GI tract, such as IBS and IBD, well-characterised bidirectional processes between immune cells and mucosal nerve fibres contribute to pathogenesis and symptom generation. Sensory alterations in these conditions such as nerve fibre outgrowth and hypersensitivity can be driven by inflammatory processes, which promote visceral pain signalling. This review will examine what is currently known of the molecular pathways linking inflammation and sensory perception leading to the development of GORD symptoms and explore potentially relevant mechanisms in other GI regions which may indicate new areas in GORD research.
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Affiliation(s)
- Tom Leech
- Centre for Neuroscience, Surgery and Trauma, Blizard Institute, Faculty of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London, E1 2AT, UK
| | - Madusha Peiris
- Centre for Neuroscience, Surgery and Trauma, Blizard Institute, Faculty of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London, E1 2AT, UK.
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2
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Fialho MFP, Brum ES, Becker G, Brusco I, Oliveira SM. Kinin B2 and B1 Receptors Activation Sensitize the TRPA1 Channel Contributing to Anastrozole-Induced Pain Symptoms. Pharmaceutics 2023; 15:pharmaceutics15041136. [PMID: 37111622 PMCID: PMC10143169 DOI: 10.3390/pharmaceutics15041136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/25/2023] [Accepted: 03/30/2023] [Indexed: 04/07/2023] Open
Abstract
Aromatase inhibitors (AIs) cause symptoms of musculoskeletal pain, and some mechanisms have been proposed to explain them. However, signaling pathways downstream from kinin B2 (B2R) and B1 (B1R) receptor activation and their possible sensitizing of the Transient Receptor Potential Ankyrin 1 (TRPA1) remain unknown. The interaction between the kinin receptor and the TRPA1 channel in male C57BL/6 mice treated with anastrozole (an AI) was evaluated. PLC/PKC and PKA inhibitors were used to evaluate the signaling pathways downstream from B2R and B1R activation and their effect on TRPA1 sensitization. Anastrozole caused mechanical allodynia and muscle strength loss in mice. B2R (Bradykinin), B1R (DABk), or TRPA1 (AITC) agonists induced overt nociceptive behavior and enhanced and prolonged the painful parameters in anastrozole-treated mice. All painful symptoms were reduced by B2R (Icatibant), B1R (DALBk), or TRPA1 (A967079) antagonists. We observed the interaction between B2R, B1R, and the TRPA1 channel in anastrozole-induced musculoskeletal pain, which was dependent on the activation of the PLC/PKC and PKA signaling pathways. TRPA1 seems to be sensitized by mechanisms dependent on the activation of PLC/PKC, and PKA due to kinin receptors stimulation in anastrozole-treated animals. Thus, regulating this signaling pathway could contribute to alleviating AIs-related pain symptoms, patients’ adherence to therapy, and disease control.
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Affiliation(s)
- Maria Fernanda Pessano Fialho
- Graduate Program in Biological Sciences, Biochemical Toxicology, Center of Natural and Exact Sciences, Federal University of Santa Maria, Camobi, Santa Maria 97105-900, RS, Brazil
| | - Evelyne Silva Brum
- Graduate Program in Biological Sciences, Biochemical Toxicology, Center of Natural and Exact Sciences, Federal University of Santa Maria, Camobi, Santa Maria 97105-900, RS, Brazil
| | - Gabriela Becker
- Graduate Program in Biological Sciences, Biochemical Toxicology, Center of Natural and Exact Sciences, Federal University of Santa Maria, Camobi, Santa Maria 97105-900, RS, Brazil
| | - Indiara Brusco
- Graduate Program in Biological Sciences, Biochemical Toxicology, Center of Natural and Exact Sciences, Federal University of Santa Maria, Camobi, Santa Maria 97105-900, RS, Brazil
| | - Sara Marchesan Oliveira
- Graduate Program in Biological Sciences, Biochemical Toxicology, Center of Natural and Exact Sciences, Federal University of Santa Maria, Camobi, Santa Maria 97105-900, RS, Brazil
- Department of Biochemical and Molecular Biology, Center of Natural and Exact Sciences, Federal University of Santa Maria, Camobi, Santa Maria 97105-900, RS, Brazil
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3
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Yu M, Chang C, Undem BJ, Yu S. Capsaicin-Sensitive Vagal Afferent Nerve-Mediated Interoceptive Signals in the Esophagus. Molecules 2021; 26:3929. [PMID: 34203134 PMCID: PMC8271978 DOI: 10.3390/molecules26133929] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 06/23/2021] [Accepted: 06/24/2021] [Indexed: 01/14/2023] Open
Abstract
Heartburn and non-cardiac chest pain are the predominant symptoms in many esophageal disorders, such as gastroesophageal reflux disease (GERD), non-erosive reflux disease (NERD), functional heartburn and chest pain, and eosinophilic esophagitis (EoE). At present, neuronal mechanisms underlying the process of interoceptive signals in the esophagus are still less clear. Noxious stimuli can activate a subpopulation of primary afferent neurons at their nerve terminals in the esophagus. The evoked action potentials are transmitted through both the spinal and vagal pathways to their central terminals, which synapse with the neurons in the central nervous system to induce esophageal nociception. Over the last few decades, progress has been made in our understanding on the peripheral and central neuronal mechanisms of esophageal nociception. In this review, we focus on the roles of capsaicin-sensitive vagal primary afferent nodose and jugular C-fiber neurons in processing nociceptive signals in the esophagus. We briefly compare their distinctive phenotypic features and functional responses to mechanical and chemical stimulations in the esophagus. Then, we summarize activation and/or sensitization effects of acid, inflammatory cells (eosinophils and mast cells), and mediators (ATP, 5-HT, bradykinin, adenosine, S1P) on these two nociceptive C-fiber subtypes. Lastly, we discuss the potential roles of capsaicin-sensitive esophageal afferent nerves in processing esophageal sensation and nociception. A better knowledge of the mechanism of nociceptive signal processes in primary afferent nerves in the esophagus will help to develop novel treatment approaches to relieve esophageal nociceptive symptoms, especially those that are refractory to proton pump inhibitors.
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Affiliation(s)
| | | | | | - Shaoyong Yu
- Department of Medicine, Johns Hopkins University School of Medicine, Ross Research Building, 720 Rutland Ave, Baltimore, MD 21205, USA; (M.Y.); (C.C.); (B.J.U.)
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4
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Balestrini A, Joseph V, Dourado M, Reese RM, Shields SD, Rougé L, Bravo DD, Chernov-Rogan T, Austin CD, Chen H, Wang L, Villemure E, Shore DGM, Verma VA, Hu B, Chen Y, Leong L, Bjornson C, Hötzel K, Gogineni A, Lee WP, Suto E, Wu X, Liu J, Zhang J, Gandham V, Wang J, Payandeh J, Ciferri C, Estevez A, Arthur CP, Kortmann J, Wong RL, Heredia JE, Doerr J, Jung M, Vander Heiden JA, Roose-Girma M, Tam L, Barck KH, Carano RAD, Ding HT, Brillantes B, Tam C, Yang X, Gao SS, Ly JQ, Liu L, Chen L, Liederer BM, Lin JH, Magnuson S, Chen J, Hackos DH, Elstrott J, Rohou A, Safina BS, Volgraf M, Bauer RN, Riol-Blanco L. A TRPA1 inhibitor suppresses neurogenic inflammation and airway contraction for asthma treatment. J Exp Med 2021; 218:211821. [PMID: 33620419 PMCID: PMC7918756 DOI: 10.1084/jem.20201637] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/19/2020] [Accepted: 12/23/2020] [Indexed: 12/31/2022] Open
Abstract
Despite the development of effective therapies, a substantial proportion of asthmatics continue to have uncontrolled symptoms, airflow limitation, and exacerbations. Transient receptor potential cation channel member A1 (TRPA1) agonists are elevated in human asthmatic airways, and in rodents, TRPA1 is involved in the induction of airway inflammation and hyperreactivity. Here, the discovery and early clinical development of GDC-0334, a highly potent, selective, and orally bioavailable TRPA1 antagonist, is described. GDC-0334 inhibited TRPA1 function on airway smooth muscle and sensory neurons, decreasing edema, dermal blood flow (DBF), cough, and allergic airway inflammation in several preclinical species. In a healthy volunteer Phase 1 study, treatment with GDC-0334 reduced TRPA1 agonist-induced DBF, pain, and itch, demonstrating GDC-0334 target engagement in humans. These data provide therapeutic rationale for evaluating TRPA1 inhibition as a clinical therapy for asthma.
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Affiliation(s)
- Alessia Balestrini
- Department of Immunology Discovery, Genentech, Inc., South San Francisco, CA
| | - Victory Joseph
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Michelle Dourado
- Department of Neuroscience, Genentech, Inc., South San Francisco, CA
| | - Rebecca M Reese
- Department of Neuroscience, Genentech, Inc., South San Francisco, CA
| | - Shannon D Shields
- Department of Neuroscience, Genentech, Inc., South San Francisco, CA
| | - Lionel Rougé
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA
| | - Daniel D Bravo
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, CA
| | - Tania Chernov-Rogan
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, CA
| | - Cary D Austin
- Department of Pathology, Genentech, Inc., South San Francisco, CA
| | - Huifen Chen
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Lan Wang
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Elisia Villemure
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Daniel G M Shore
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Vishal A Verma
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Baihua Hu
- Pharmaron-Beijing Co. Ltd., BDA, Beijing, People's Republic of China
| | - Yong Chen
- Pharmaron-Beijing Co. Ltd., BDA, Beijing, People's Republic of China
| | - Laurie Leong
- Department of Pathology, Genentech, Inc., South San Francisco, CA
| | - Chris Bjornson
- Department of Pathology, Genentech, Inc., South San Francisco, CA
| | - Kathy Hötzel
- Department of Pathology, Genentech, Inc., South San Francisco, CA
| | - Alvin Gogineni
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Wyne P Lee
- Department of Translational Immunology, Genentech, Inc., South San Francisco, CA
| | - Eric Suto
- Department of Translational Immunology, Genentech, Inc., South San Francisco, CA
| | - Xiumin Wu
- Department of Translational Immunology, Genentech, Inc., South San Francisco, CA
| | - John Liu
- Department of Translational Immunology, Genentech, Inc., South San Francisco, CA
| | - Juan Zhang
- Department of Translational Immunology, Genentech, Inc., South San Francisco, CA
| | - Vineela Gandham
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Jianyong Wang
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, CA
| | - Jian Payandeh
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA
| | - Claudio Ciferri
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA
| | - Alberto Estevez
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA
| | | | - Jens Kortmann
- Department of Immunology Discovery, Genentech, Inc., South San Francisco, CA
| | - Ryan L Wong
- Department of Immunology Discovery, Genentech, Inc., South San Francisco, CA
| | - Jose E Heredia
- Department of Immunology Discovery, Genentech, Inc., South San Francisco, CA
| | - Jonas Doerr
- Department of Molecular Biology, Genentech, Inc., South San Francisco, CA
| | - Min Jung
- Department of OMNI Bioinformatics, Genentech, Inc., South San Francisco, CA
| | | | - Merone Roose-Girma
- Department of Molecular Biology, Genentech, Inc., South San Francisco, CA
| | - Lucinda Tam
- Department of Molecular Biology, Genentech, Inc., South San Francisco, CA
| | - Kai H Barck
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Richard A D Carano
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Han Ting Ding
- Department of Clinical Pharmacology, Genentech, Inc., South San Francisco, CA
| | - Bobby Brillantes
- Department of Biomolecular Resources, Genentech, Inc., South San Francisco, CA
| | - Christine Tam
- Department of Biomolecular Resources, Genentech, Inc., South San Francisco, CA
| | - Xiaoying Yang
- Department of Product Development Biometric Biostatistics, Genentech, Inc., South San Francisco, CA
| | - Simon S Gao
- Department of Clinical Imaging, Genentech, Inc., South San Francisco, CA
| | - Justin Q Ly
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, CA
| | - Liling Liu
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, CA
| | - Liuxi Chen
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, CA
| | - Bianca M Liederer
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, CA
| | - Joseph H Lin
- Department of Early Clinical Development, Genentech, Inc., South San Francisco, CA
| | - Steven Magnuson
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Jun Chen
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, CA
| | - David H Hackos
- Department of Neuroscience, Genentech, Inc., South San Francisco, CA
| | - Justin Elstrott
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Alexis Rohou
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA
| | - Brian S Safina
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Matthew Volgraf
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Rebecca N Bauer
- Department of OMNI-Biomarker Development, Genentech, Inc., South San Francisco, CA
| | - Lorena Riol-Blanco
- Department of Immunology Discovery, Genentech, Inc., South San Francisco, CA
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5
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Ru F, Pavelkova N, Krajewski JL, McDermott JS, Undem BJ, Kollarik M. Stimulus intensity-dependent recruitment of Na V1 subunits in action potential initiation in nerve terminals of vagal C-fibers innervating the esophagus. Am J Physiol Gastrointest Liver Physiol 2020; 319:G443-G453. [PMID: 32726130 PMCID: PMC7654645 DOI: 10.1152/ajpgi.00122.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We investigated voltage-gated sodium channel (NaV1) subunits that regulate action potential initiation in the nerve terminals of vagal nodose C-fibers innervating the esophagus. Extracellular single fiber recordings were made from the nodose C-fibers, with mechanically sensitive nerve terminals in the isolated innervated guinea pig esophagus. NaV1 inhibitors were selectively delivered to the tissue-containing nerve terminals. Graded esophageal distention was used for mechanical stimulation. The NaV1.7 inhibitor PF-05089771 nearly abolished action potential initiation in response to low levels of esophageal distention but only partially inhibited the response to higher levels of esophageal distention. The PF-05089771-insensitive component of the response progressively increased (up to ≈50%) with increasing esophageal distention and was abolished by tetrodotoxin (TTX). In addition to NaV1.7, nodose C-fiber [transient receptor potential channel-vanilloid subfamily member 1 (TRPV1)-positive] neurons retrogradely labeled from the esophagus expressed mRNA for multiple TTX-sensitive NaV1s. The group NaV1.1, NaV1.2, and NaV1.3 inhibitor ICA-121431 inhibited but did not abolish the PF-05089771-insensitive component of the response to high level of esophageal distention. However, combination of ICA-121431 with compound 801, which also inhibits NaV1.7 and NaV1.6, nearly abolished the response to the high level of esophageal distention. Our data indicate that the action potential initiation in esophageal nodose C-fibers evoked by low (innocuous) levels of esophageal distention is mediated by NaV1.7. However, the response evoked by higher (noxious) levels of esophageal distention has a progressively increasing NaV1.7-independent component that involves multiple TTX-sensitive NaV1s. The stimulus intensity-dependent recruitment of NaV1s may offer novel opportunities for strategic targeting of NaV1 subunits for inhibition of nociceptive signaling in visceral C-fibers.NEW & NOTEWORTHY We report that pharmacologically distinguishable voltage-gated sodium channels (NaV1) mediate action potential initiation at low (innocuous) versus high (noxious) intensity of esophageal distention in nerve terminals of vagal nodose C-fibers. Action potential initiation at low intensity is entirely dependent on NaV1.7; however, additional tetrodotoxin (TTX)-sensitive NaV1s are recruited at higher intensity of distention. This is the first demonstration that NaV1s underlying action potential initiation in visceral C-fibers depend on the intensity of the stimulus.
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Affiliation(s)
- Fei Ru
- 1Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Nikoleta Pavelkova
- 2University of South Florida, Morsani College of Medicine, Tampa, Florida
| | | | | | - Bradley J. Undem
- 1Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Marian Kollarik
- 2University of South Florida, Morsani College of Medicine, Tampa, Florida
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6
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Talavera K, Startek JB, Alvarez-Collazo J, Boonen B, Alpizar YA, Sanchez A, Naert R, Nilius B. Mammalian Transient Receptor Potential TRPA1 Channels: From Structure to Disease. Physiol Rev 2019; 100:725-803. [PMID: 31670612 DOI: 10.1152/physrev.00005.2019] [Citation(s) in RCA: 218] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The transient receptor potential ankyrin (TRPA) channels are Ca2+-permeable nonselective cation channels remarkably conserved through the animal kingdom. Mammals have only one member, TRPA1, which is widely expressed in sensory neurons and in non-neuronal cells (such as epithelial cells and hair cells). TRPA1 owes its name to the presence of 14 ankyrin repeats located in the NH2 terminus of the channel, an unusual structural feature that may be relevant to its interactions with intracellular components. TRPA1 is primarily involved in the detection of an extremely wide variety of exogenous stimuli that may produce cellular damage. This includes a plethora of electrophilic compounds that interact with nucleophilic amino acid residues in the channel and many other chemically unrelated compounds whose only common feature seems to be their ability to partition in the plasma membrane. TRPA1 has been reported to be activated by cold, heat, and mechanical stimuli, and its function is modulated by multiple factors, including Ca2+, trace metals, pH, and reactive oxygen, nitrogen, and carbonyl species. TRPA1 is involved in acute and chronic pain as well as inflammation, plays key roles in the pathophysiology of nearly all organ systems, and is an attractive target for the treatment of related diseases. Here we review the current knowledge about the mammalian TRPA1 channel, linking its unique structure, widely tuned sensory properties, and complex regulation to its roles in multiple pathophysiological conditions.
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Affiliation(s)
- Karel Talavera
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Justyna B Startek
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Julio Alvarez-Collazo
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Brett Boonen
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Yeranddy A Alpizar
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Alicia Sanchez
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Robbe Naert
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Bernd Nilius
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
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7
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Sun H, Meeker S, Undem BJ. Role of TRP channels in G q-coupled protease-activated receptor 1-mediated activation of mouse nodose pulmonary C-fibers. Am J Physiol Lung Cell Mol Physiol 2019; 318:L192-L199. [PMID: 31664854 DOI: 10.1152/ajplung.00301.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
We evaluated the mechanisms underlying protease-activated receptor 1 (PAR1)-mediated activation of nodose C-fibers in mouse lungs. The PAR1-induced action potential discharge at the terminals was strongly inhibited in phospholipase C-β3 (PLCβ3)-deficient animals. At the level of the cell soma, PAR1 activation led to an increase in cytosolic calcium that was largely inhibited by transient receptor potential (TRP) A1 antagonism. Patch-clamp recordings, however, revealed that neither TRPA1 nor TRPV1 or any other ruthenium red-sensitive ion channels are required for the PAR1-mediated inward current or membrane depolarization in isolated nodose neurons. Consistent with these findings, PAR1-mediated action potential discharge in mouse lung nodose C-fiber terminals was unaltered in Trpa1/Trpv1 double-knockout animals and Trpc3/Trpc6 double-knockout animals. The activation of the C-fibers was also not inhibited by ruthenium red at concentrations that blocked TRPV1- and TRPA1-dependent responses. The biophysical data show that PAR1/Gq-mediated activation of nodose C-fibers may involve multiple ion channels downstream from PLCβ3 activation. TRPA1 is an ion channel that participates in PAR1/Gq-mediated elevation in intracellular calcium. There is little evidence, however, that TRPA1, TRPV1, TRPC3, TRPC6, or other ruthenium red-sensitive TRP channels are required for PAR1/Gq-PLCβ3-mediated membrane depolarization and action potential discharge in bronchopulmonary nodose C-fibers in the mouse.
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Affiliation(s)
- Hui Sun
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sonya Meeker
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Bradley J Undem
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
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8
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Huang Y, Patil MJ, Yu M, Liptak P, Undem BJ, Dong X, Wang G, Yu S. Effects of ginger constituent 6-shogaol on gastroesophageal vagal afferent C-fibers. Neurogastroenterol Motil 2019; 31:e13585. [PMID: 30947399 PMCID: PMC6522279 DOI: 10.1111/nmo.13585] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 02/22/2019] [Accepted: 03/05/2019] [Indexed: 02/08/2023]
Abstract
BACKGROUND Ginger has been used as an herbal medicine worldwide to relieve nausea/vomiting and gastrointestinal discomfort, but the cellular and molecular mechanisms of its neuronal action remain unclear. The present study aimed to determine the effects of ginger constituent 6-shogaol on gastroesophageal vagal nodose C-fibers. METHODS Extracellular single-unit recording and two-photon nodose neuron imaging were performed, respectively, in ex vivo gastroesophageal-vagal preparations from wild type and Pirt-GCaMP6 transgenic mice. The action potential discharge or calcium influx evoked by mechanical distension and chemical perfusions applied to the gastroesophageal vagal afferent nerve endings were recorded, respectively, at their intact neuronal cell soma in vagal nodose ganglia. The effects of 6-shogaol on nodose C-fiber neurons were then compared and determined. KEY RESULTS Gastroesophageal application of 6-shogaol-elicited intensive calcium influxes in nodose neurons and evoked robust action potential discharges in most studied nodose C-fibers. Such activation effects were followed by a desensitized response to the second application of 6-shogaol. However, action potential discharges evoked by esophageal mechanical distension, after 6-shogaol perfusion, did not significantly change. Pretreatment with TRPA1 selective blocker HC-030031 inhibited 6-shogaol-induced action potential discharges in gastric and esophageal nodose C-fiber neurons, suggesting that TRPA1 played a role in mediating 6-shogaol-induced activation response. CONCLUSION AND INFERENCES This study provides evidence that ginger constituent 6-shogaol directly activates vagal afferent C-fiber peripheral gastrointestinal endings. This activation leads to desensitization to subsequent application of 6-shogaol but not subsequent esophageal mechanical distension. Further investigation is required to establish a possible contribution in its anti-emetic effects.
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Affiliation(s)
- Yongming Huang
- Department of Medicine, Johns Hopkins University School of Medicine, USA,Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Mayur J. Patil
- Department of Medicine, Johns Hopkins University School of Medicine, USA
| | - Mingwei Yu
- Department of Medicine, Johns Hopkins University School of Medicine, USA
| | - Peter Liptak
- Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Slovakia
| | - Bradley J. Undem
- Department of Medicine, Johns Hopkins University School of Medicine, USA
| | - Xinzhong Dong
- Department of Neuroscience, Solomon H. Snyder Johns Hopkins University School of Medicine, USA
| | - Guobin Wang
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Shaoyong Yu
- Department of Medicine, Johns Hopkins University School of Medicine, USA,Corresponding: Shaoyong Yu, MD, MPH., Johns Hopkins University School of Medicine, Ross Research Building, Room 945, 720 Rutland Ave, Baltimore 21205, Phone: (410) 502-2455,
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9
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Beskhmelnitsyna EA, Pokrovskii MV, Kulikov AL, Peresypkina AA, Varavin EI. Study of Anti-inflammatory Activity of a New Non-opioid Analgesic on the Basis of a Selective Inhibitor of TRPA1 Ion Channels. Antiinflamm Antiallergy Agents Med Chem 2019; 18:110-125. [PMID: 30734687 DOI: 10.2174/1871523018666190208123700] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/22/2019] [Accepted: 01/28/2019] [Indexed: 01/01/2023]
Abstract
INTRODUCTION Nowadays, the group of NSAIDs is used the most widely in order to treat the inflammatory process. But its long-term administration increases the risk of complications of pharmacotherapy. Therefore, today it is urgent to search for new molecules that can selectively block biological targets that directly perceive inflammatory mediators. One of such targets is TRPA1. ZC02-0012, a compound from the group of substituted pyrazinopyrimidinones, which is a selective inhibitor of TRPA1 ion channel. OBJECTIVE The aim of our study was to study the anti-inflammatory activity of an innovative molecule under the laboratory code ZC02-0012 from the group of selective inhibitors of TRPA1 ion channel. MATERIALS AND METHODS Anti-inflammatory activity of ZC02-0012 was studied on the model of acute exudative inflammation of the paw in response to subplantar injection in the right hind paw of mice with 0.02 ml of 2% formaldehyde solution. The mass of the paw was measured after 4 hours (peak edema) after phlogistic injection. The test substance and the reference drug was administered intragastrically or intramuscularly 45 minutes before the injection of formaldehyde solution. The presence and intensity of antiinflammatory activity was judged by the inhibitory effect, represented in percent. RESULTS AND DISCUSSION Selective inhibitor of the TRPA1 ion channel ZC02-0012 revealed the anti-inflammatory activity at doses of 3 and 9 mg/kg, its intensity is comparable to diclofenac sodium. CONCLUSION The selective inhibitor of the ion channel TRPA1, a substance under code ZC02-0012, has an anti-inflammatory activity comparable with diclofenac sodium.
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Affiliation(s)
- Evgeniya A Beskhmelnitsyna
- Department of Pharmacology and Clinical pharmacology, Medical Faculty of Belgorod National Research University, 85 Pobeda St., Belgorod, 308015, Russian Federation
| | - Mikhail V Pokrovskii
- Department of Pharmacology and Clinical pharmacology, Medical Faculty of Belgorod National Research University, 85 Pobeda St., Belgorod, 308015, Russian Federation
| | - Aleksandr L Kulikov
- Research Institute of Pharmacology of Living systems of Belgorod National Research University, 85 Pobeda St., Belgorod, 308015, Russian Federation
| | - Anna A Peresypkina
- Department of Pharmacology and Clinical pharmacology, Medical Faculty of Belgorod National Research University, 85 Pobeda St., Belgorod, 308015, Russian Federation
| | - Evgeniy I Varavin
- Physician Training Faculty for Aerospace Forces of Kirov Military Medical Academy, 6 Academician Lebedev St., Saint Petersburg, 194044, Russian Federation
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10
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Yu X, Patil MJ, Yu M, Liu Y, Wang J, Undem BJ, Yu S. Sphingosine-1-phosphate selectively activates vagal afferent C-fiber subtype in guinea pig esophagus. Neurogastroenterol Motil 2018; 30:e13359. [PMID: 29673037 DOI: 10.1111/nmo.13359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 03/25/2018] [Indexed: 02/08/2023]
Abstract
BACKGROUND Activation and sensitization of visceral afferent nerves by inflammatory mediators play important roles in visceral nociception. Sphingosine-1-phosphate (S1P) is a lipid with intracellular and extracellular functions. Extracellularly, it can act as an autacoid via interactions with S1P receptors. The present study aims to determine the effect of S1P on esophageal vagal afferent nerve functions. METHODS Extracellular single-unit recordings were performed in ex vivo guinea pig esophageal-vagal preparations. The action potentials (APs) evoked by mechanical distension and chemical perfusions applied to the vagal afferent nerve endings in the esophagus were recorded at their intact neuronal cell bodies in either nodose or jugular ganglia. The effects of S1P and its receptor subtype agonists on vagal afferents were recorded and compared. The expression of S1P receptors (S1PR1-3) in esophageal-labeled vagal nodose and jugular neurons was studied by single-cell RT-PCR. KEY RESULTS Sphingosine-1-phosphate evoked AP discharges in almost all esophageal jugular but not nodose C-fibers without changing their responses to esophageal distension. Esophageal-labeled vagal nodose and jugular neurons highly expressed transcripts of S1PR1 and S1PR3. Agonists of S1PR1 and S1PR3 each partially mimicked S1P-induced effect in jugular C-fibers, suggesting that these receptors may contribute partially to S1P-induced activation effect on esophageal jugular C-fiber subtype. CONCLUSIONS & INFERENCES These data, for the first time, demonstrated a selective activation effect of S1P on vagal afferent nerve subtype in the gastrointestinal tract. This may help to better understand its role in visceral inflammatory nociception.
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Affiliation(s)
- X Yu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - M J Patil
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - M Yu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Y Liu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - J Wang
- Department of Pathology, Wayne State University School of Medicine, Detroit, MI, USA
| | - B J Undem
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - S Yu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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11
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Choi SI, Hwang SW. Depolarizing Effectors of Bradykinin Signaling in Nociceptor Excitation in Pain Perception. Biomol Ther (Seoul) 2018; 26:255-267. [PMID: 29378387 PMCID: PMC5933892 DOI: 10.4062/biomolther.2017.127] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Revised: 10/13/2017] [Accepted: 10/24/2017] [Indexed: 12/23/2022] Open
Abstract
Inflammation is one of the main causes of pathologic pain. Knowledge of the molecular links between inflammatory signals and pain-mediating neuronal signals is essential for understanding the mechanisms behind pain exacerbation. Some inflammatory mediators directly modulate the excitability of pain-mediating neurons by contacting the receptor molecules expressed in those neurons. For decades, many discoveries have accumulated regarding intraneuronal signals from receptor activation through electrical depolarization for bradykinin, a major inflammatory mediator that is able to both excite and sensitize pain-mediating nociceptor neurons. Here, we focus on the final effectors of depolarization, the neuronal ion channels, whose functionalities are specifically affected by bradykinin stimulation. Particular G-protein coupled signaling cascades specialized for each specific depolarizer ion channels are summarized. Some of these ion channels not only serve as downstream effectors but also play critical roles in relaying specific pain modalities such as thermal or mechanical pain. Accordingly, specific pain phenotypes altered by bradykinin stimulation are also discussed. Some members of the effector ion channels are both activated and sensitized by bradykinin-induced neuronal signaling, while others only sensitized or inhibited, which are also introduced. The present overview of the effect of bradykinin on nociceptor neuronal excitability at the molecular level may contribute to better understanding of an important aspect of inflammatory pain and help future design of further research on the components involved and pain modulating strategies.
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Affiliation(s)
- Seung-In Choi
- Department of Biomedical Sciences and Department of Physiology, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Sun Wook Hwang
- Department of Biomedical Sciences and Department of Physiology, Korea University College of Medicine, Seoul 02841, Republic of Korea
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12
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Moore C, Gupta R, Jordt SE, Chen Y, Liedtke WB. Regulation of Pain and Itch by TRP Channels. Neurosci Bull 2018; 34:120-142. [PMID: 29282613 PMCID: PMC5799130 DOI: 10.1007/s12264-017-0200-8] [Citation(s) in RCA: 191] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 10/27/2017] [Indexed: 02/07/2023] Open
Abstract
Nociception is an important physiological process that detects harmful signals and results in pain perception. In this review, we discuss important experimental evidence involving some TRP ion channels as molecular sensors of chemical, thermal, and mechanical noxious stimuli to evoke the pain and itch sensations. Among them are the TRPA1 channel, members of the vanilloid subfamily (TRPV1, TRPV3, and TRPV4), and finally members of the melastatin group (TRPM2, TRPM3, and TRPM8). Given that pain and itch are pro-survival, evolutionarily-honed protective mechanisms, care has to be exercised when developing inhibitory/modulatory compounds targeting specific pain/itch-TRPs so that physiological protective mechanisms are not disabled to a degree that stimulus-mediated injury can occur. Such events have impeded the development of safe and effective TRPV1-modulating compounds and have diverted substantial resources. A beneficial outcome can be readily accomplished via simple dosing strategies, and also by incorporating medicinal chemistry design features during compound design and synthesis. Beyond clinical use, where compounds that target more than one channel might have a place and possibly have advantageous features, highly specific and high-potency compounds will be helpful in mechanistic discovery at the structure-function level.
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Affiliation(s)
- Carlene Moore
- Department of Neurology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Rupali Gupta
- Department of Neurology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Sven-Eric Jordt
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Yong Chen
- Department of Neurology, Duke University Medical Center, Durham, NC, 27710, USA.
| | - Wolfgang B Liedtke
- Department of Neurology, Duke University Medical Center, Durham, NC, 27710, USA.
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA.
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13
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Abstract
Functional heartburn (FH) is defined as a functional esophageal disorder characterized by symptoms of chronic heartburn with no apparent correlation to acid or nonacid reflux. In addition, its symptoms persist despite the lack of organic abnormalities or inflammation, esophageal motility disorders, or metabolic disorders. Although conditions presenting with esophageal symptoms without endoscopic abnormalities were previously categorized as nonerosive reflux disease, such conditions are now classified into 3 categories under Rome IV criteria: nonerosive reflux disease, reflux hypersensitivity, and FH. Although many aspects of FH remain unclear, its onset mechanism is considered to be strongly associated with peripheral or central sensitization, given the fact that its symptoms seem to be unrelated to gastroesophageal reflux. In addition, the cause of such hypersensitivity is an interesting topic in itself, and psychological factors, such as stress followed by increasing esophageal permeability are gaining attention as factors that can potentially influence this condition. There is a great unmet clinical need for therapeutic drugs that can be used to treat FH, and the development of novel drugs, diagnostic tests and biomarkers is eagerly awaited.
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14
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Busby LD. A Comparison of Multiple Chemical Sensitivity with Other Hypersensitivity Illnesses Suggests Evidence and a Path to Answers. ECOPSYCHOLOGY 2017. [DOI: 10.1089/eco.2017.0003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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15
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Wang R, Lu Y, Gunasekar S, Zhang Y, Benson CJ, Chapleau MW, Sah R, Abboud FM. The volume-regulated anion channel (LRRC8) in nodose neurons is sensitive to acidic pH. JCI Insight 2017; 2:e90632. [PMID: 28289711 DOI: 10.1172/jci.insight.90632] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The leucine rich repeat containing protein 8A (LRRC8A), or SWELL1, is an essential component of the volume-regulated anion channel (VRAC) that is activated by cell swelling and ionic strength. We report here for the first time to our knowledge its expression in a primary cell culture of nodose ganglia neurons and its localization in the soma, neurites, and neuronal membrane. We show that this neuronal VRAC/SWELL1 senses low external pH (pHo) in addition to hypoosmolarity. A robust sustained chloride current is seen in 77% of isolated nodose neurons following brief exposures to extracellular acid pH. Its activation involves proton efflux, intracellular alkalinity, and an increase in NOX-derived H2O2. The molecular identity of both the hypoosmolarity-induced and acid pHo-conditioned VRAC as LRRC8A (SWELL1) was confirmed by Cre-flox-mediated KO, shRNA-mediated knockdown, and CRISPR/Cas9-mediated LRRC8A deletion in HEK cells and in primary nodose neuronal cultures. Activation of VRAC by low pHo reduces neuronal injury during simulated ischemia and N-methyl-D-aspartate-induced (NMDA-induced) apoptosis. These results identify the VRAC (LRRC8A) as a dual sensor of hypoosmolarity and low pHo in vagal afferent neurons and define the mechanisms of its activation and its neuroprotective potential.
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Affiliation(s)
- Runping Wang
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Yongjun Lu
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Susheel Gunasekar
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Yanhui Zhang
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Christopher J Benson
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, USA.,Veterans Affairs Medical Center, Iowa City, Iowa, USA
| | - Mark W Chapleau
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, USA.,Veterans Affairs Medical Center, Iowa City, Iowa, USA.,Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, USA
| | - Rajan Sah
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, USA.,Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, USA
| | - François M Abboud
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, USA.,Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, USA
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16
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Lv Y, Zhou L, Tang Z, Dong J. Association and interaction analysis of diabetes mellitus and SCN10A for cardiovascular autonomic neuropathy in a Chinese population. Postgrad Med J 2016; 93:344-348. [PMID: 27729462 DOI: 10.1136/postgradmedj-2016-134202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 09/07/2016] [Accepted: 09/21/2016] [Indexed: 01/29/2023]
Abstract
BACKGROUND This study assessed the extent to which diabetes mellitus (DM) and SCN10A (rs7375036) and their interaction impact on cardiovascular autonomic neuropathy (CAN) susceptibility in a Chinese Han sample. METHOD We performed a study in a cross-sectional dataset that included 419 patients with DM and 1557 controls who were genotyped for the presence of the SCN10A rs7375036 polymorphisms. Genotyping was performed by iPLEX technology. The associations of rs7375036 and DM with CAN was assessed by using univariate and multivariate logistic regression controlling for confounders. The interaction between rs7375036 and DM for CAN susceptibility on an additive scale was calculated by using the relative excess risk due to interaction (RERI), the proportion attributable to interaction (AP), and the synergy index (S). RESULTS The univariate logistic analyses failed to show an association between the SCN10A rs7375036 polymorphisms and CAN. Interestingly, a novel interaction effect of SCN10A rs7375036 and DM on CAN was assessed (p=0.055; RERI=3.515, 95% CI 1.829 to 5.805; AP=0.632, 95% CI -0.368 to 1.632; S=4.361, 95% CI 2.071 to 9.184). CONCLUSIONS Our findings suggest that there are interaction effects of DM and SCN10A (rs7375036) that influence the development of CAN. TRIAL REGISTRATION NUMBER NCT02461342.
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Affiliation(s)
- Yubao Lv
- Department of Integrative Medicine, Huashan Hospital, Fudan University, Shanghai, China.,Institutes of Integrative Medicine, Fudan University, Shanghai, China
| | - Linuo Zhou
- Institution of Diabetology, Fudan University, Shanghai, China
| | - Zihui Tang
- Department of Integrative Medicine, Huashan Hospital, Fudan University, Shanghai, China.,Institutes of Integrative Medicine, Fudan University, Shanghai, China
| | - Jingcheng Dong
- Department of Integrative Medicine, Huashan Hospital, Fudan University, Shanghai, China.,Institutes of Integrative Medicine, Fudan University, Shanghai, China
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17
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Allais L, De Smet R, Verschuere S, Talavera K, Cuvelier CA, Maes T. Transient Receptor Potential Channels in Intestinal Inflammation: What Is the Impact of Cigarette Smoking? Pathobiology 2016; 84:1-15. [DOI: 10.1159/000446568] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 05/02/2016] [Indexed: 11/19/2022] Open
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18
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Brozmanova M, Mazurova L, Ru F, Tatar M, Hu Y, Yu S, Kollarik M. Mechanisms of the adenosine A2A receptor-induced sensitization of esophageal C fibers. Am J Physiol Gastrointest Liver Physiol 2016; 310:G215-23. [PMID: 26564719 PMCID: PMC4971813 DOI: 10.1152/ajpgi.00350.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 11/09/2015] [Indexed: 01/31/2023]
Abstract
Clinical studies indicate that adenosine contributes to esophageal mechanical hypersensitivity in some patients with pain originating in the esophagus. We have previously reported that the esophageal vagal nodose C fibers express the adenosine A2A receptor. Here we addressed the hypothesis that stimulation of the adenosine A2A receptor induces mechanical sensitization of esophageal C fibers by a mechanism involving transient receptor potential A1 (TRPA1). Extracellular single fiber recordings of activity originating in C-fiber terminals were made in the ex vivo vagally innervated guinea pig esophagus. The adenosine A2A receptor-selective agonist CGS21680 induced robust, reversible sensitization of the response to esophageal distention (10-60 mmHg) in a concentration-dependent fashion (1-100 nM). At the half-maximally effective concentration (EC50: ≈3 nM), CGS21680 induced an approximately twofold increase in the mechanical response without causing an overt activation. This sensitization was abolished by the selective A2A antagonist SCH58261. The adenylyl cyclase activator forskolin mimicked while the nonselective protein kinase inhibitor H89 inhibited mechanical sensitization by CGS21680. CGS21680 did not enhance the response to the purinergic P2X receptor agonist α,β-methylene-ATP, indicating that CGS21680 does not nonspecifically sensitize to all stimuli. Mechanical sensitization by CGS21680 was abolished by pretreatment with two structurally different TRPA1 antagonists AP18 and HC030031. Single cell RT-PCR and whole cell patch-clamp studies in isolated esophagus-specific nodose neurons revealed the expression of TRPA1 in A2A-positive C-fiber neurons and demonstrated that CGS21682 potentiated TRPA1 currents evoked by allylisothiocyanate. We conclude that stimulation of the adenosine A2A receptor induces mechanical sensitization of nodose C fibers by a mechanism sensitive to TRPA1 antagonists indicating the involvement of TRPA1.
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Affiliation(s)
- M. Brozmanova
- 1Department of Pathophysiology and Biomedical Center Martin, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia; and
| | - L. Mazurova
- 1Department of Pathophysiology and Biomedical Center Martin, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia; and
| | - F. Ru
- 2Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - M. Tatar
- 1Department of Pathophysiology and Biomedical Center Martin, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia; and
| | - Y. Hu
- 2Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - S. Yu
- 2Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - M. Kollarik
- 1Department of Pathophysiology and Biomedical Center Martin, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia; and ,2Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland
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Abstract
Visceral pain is a highly complex entity whose experience is variable in health and disease. It can occur in patients with organic disease and also in those without any readily identifiable structural or biochemical abnormality such as in the functional gastrointestinal disorders (FGID). Despite considerable progress in our understanding of the culpable underlying mechanisms significant knowledge gaps remain, representing a significant unmet need in gastroenterology. A key, but not universal, pathological feature is that patients with FGID often display heightened sensitivity to experimental gut stimulation, termed visceral hypersensitivity. A plethora of factors have been proposed to account for this epiphenomenon including peripheral sensitization, central sensitization, aberrant central processing, genetic, psychological and abnormalities within the stress responsive systems. Further research is needed, bringing together complementary research themes from a diverse array of academic disciplines ranging from gastroenterology to nociceptive physiology to functional neuro-imaging, to address this unmet need.
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Affiliation(s)
- Adam D Farmer
- Department of Gastroenterology, Shrewsbury & Telford Hospitals NHS Trust, Princess Royal Hospital, Apley Castle, Telford, Shropshire, UK ; Neurogastroenterology Group, Blizard Institute of Cell & Molecular Science, Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine & Dentistry, Queen Mary University of London, London, UK
| | - Qasim Aziz
- Neurogastroenterology Group, Blizard Institute of Cell & Molecular Science, Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine & Dentistry, Queen Mary University of London, London, UK
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20
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Yu X, Yu M, Liu Y, Yu S. TRP channel functions in the gastrointestinal tract. Semin Immunopathol 2015; 38:385-96. [PMID: 26459157 DOI: 10.1007/s00281-015-0528-y] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 09/07/2015] [Indexed: 12/14/2022]
Abstract
Transient receptor potential (TRP) channels are predominantly distributed in both somatic and visceral sensory nervous systems and play a crucial role in sensory transduction. As the largest visceral organ system, the gastrointestinal (GI) tract frequently accommodates external inputs, which stimulate sensory nerves to initiate and coordinate sensory and motor functions in order to digest and absorb nutrients. Meanwhile, the sensory nerves in the GI tract are also able to detect potential tissue damage by responding to noxious irritants. This nocifensive function is mediated through specific ion channels and receptors expressed in a subpopulation of spinal and vagal afferent nerve called nociceptor. In the last 18 years, our understanding of TRP channel expression and function in GI sensory nervous system has been continuously improved. In this review, we focus on the expressions and functions of TRPV1, TRPA1, and TRPM8 in primary extrinsic afferent nerves innervated in the esophagus, stomach, intestine, and colon and briefly discuss their potential roles in relevant GI disorders.
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Affiliation(s)
- Xiaoyun Yu
- Division of Gastroenterology & Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Ross Research Building, Room 945, 720 Rutland Ave, Baltimore, MD, 21205, USA
| | - Mingran Yu
- Division of Gastroenterology & Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Ross Research Building, Room 945, 720 Rutland Ave, Baltimore, MD, 21205, USA
| | - Yingzhe Liu
- Division of Gastroenterology & Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Ross Research Building, Room 945, 720 Rutland Ave, Baltimore, MD, 21205, USA
| | - Shaoyong Yu
- Division of Gastroenterology & Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Ross Research Building, Room 945, 720 Rutland Ave, Baltimore, MD, 21205, USA.
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21
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The TRPA1 channel in inflammatory and neuropathic pain and migraine. Rev Physiol Biochem Pharmacol 2015; 167:1-43. [PMID: 24668446 DOI: 10.1007/112_2014_18] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The transient receptor potential ankyrin 1 (TRPA1), a member of the TRP superfamily of channels, is primarily localized to a subpopulation of primary sensory neurons of the trigeminal, vagal, and dorsal root ganglia. This subset of nociceptors produces and releases the neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP), which mediate neurogenic inflammatory responses. TRPA1 is activated by a number of exogenous compounds, including molecules of botanical origin, environmental irritants, and medicines. However, the most prominent feature of TRPA1 resides in its unique sensitivity for large series of reactive byproducts of oxidative and nitrative stress. Here, the role of TRPA1 in models of different types of pain, including inflammatory and neuropathic pain and migraine, is summarized. Specific attention is paid to TRPA1 as the main contributing mechanism to the transition of mechanical and cold hypersensitivity from an acute to a chronic condition and as the primary transducing pathway by which oxidative/nitrative stress produces acute nociception, allodynia, and hyperalgesia. A series of migraine triggers or medicines have been reported to modulate TRPA1 activity and the ensuing CGRP release. Thus, TRPA1 antagonists may be beneficial in the treatment of inflammatory and neuropathic pain and migraine.
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22
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Yu X, Hu Y, Ru F, Kollarik M, Undem BJ, Yu S. TRPM8 function and expression in vagal sensory neurons and afferent nerves innervating guinea pig esophagus. Am J Physiol Gastrointest Liver Physiol 2015; 308:G489-96. [PMID: 25591866 PMCID: PMC4360048 DOI: 10.1152/ajpgi.00336.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Sensory transduction in esophageal afferents requires specific ion channels and receptors. TRPM8 is a new member of the transient receptor potential (TRP) channel family and participates in cold- and menthol-induced sensory transduction, but its role in visceral sensory transduction is still less clear. This study aims to determine TRPM8 function and expression in esophageal vagal afferent subtypes. TRPM8 agonist WS-12-induced responses were first determined in nodose and jugular neurons by calcium imaging and then investigated by whole cell patch-clamp recordings in Dil-labeled esophageal nodose and jugular neurons. Extracellular single-unit recordings were performed in nodose and jugular C fiber neurons using ex vivo esophageal-vagal preparations with intact nerve endings in the esophagus. TRPM8 mRNA expression was determined by single neuron RT-PCR in Dil-labeled esophageal nodose and jugular neurons. The TRPM8 agonist WS-12 elicited calcium influx in a subpopulation of jugular but not nodose neurons. WS-12 activated outwardly rectifying currents in esophageal Dil-labeled jugular but not nodose neurons in a dose-dependent manner, which could be inhibited by the TRPM8 inhibitor AMTB. WS-12 selectively evoked action potential discharges in esophageal jugular but not nodose C fibers. Consistently, TRPM8 transcripts were highly expressed in esophageal Dil-labeled TRPV1-positive jugular neurons. In summary, the present study demonstrated a preferential expression and function of TRPM8 in esophageal vagal jugular but not nodose neurons and C fiber subtypes. This provides a distinctive role of TRPM8 in esophageal sensory transduction and may lead to a better understanding of the mechanisms of esophageal sensation and nociception.
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Affiliation(s)
| | | | | | | | | | - Shaoyong Yu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
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23
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Liu Z, Hu Y, Yu X, Xi J, Fan X, Tse CM, Myers AC, Pasricha PJ, Li X, Yu S. Allergen challenge sensitizes TRPA1 in vagal sensory neurons and afferent C-fiber subtypes in guinea pig esophagus. Am J Physiol Gastrointest Liver Physiol 2015; 308:G482-8. [PMID: 25591867 PMCID: PMC4360047 DOI: 10.1152/ajpgi.00374.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Transient receptor potential A1 (TRPA1) is a newly defined cationic ion channel, which selectively expresses in primary sensory afferent nerve, and is essential in mediating inflammatory nociception. Our previous study demonstrated that TRPA1 plays an important role in tissue mast cell activation-induced increase in the excitability of esophageal vagal nodose C fibers. The present study aims to determine whether prolonged antigen exposure in vivo sensitizes TRPA1 in a guinea pig model of eosinophilic esophagitis (EoE). Antigen challenge-induced responses in esophageal mucosa were first assessed by histological stains and Ussing chamber studies. TRPA1 function in vagal sensory neurons was then studied by calcium imaging and by whole cell patch-clamp recordings in 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI)-labeled esophageal vagal nodose and jugular neurons. Extracellular single-unit recordings were performed in vagal nodose and jugular C-fiber neuron subtypes using ex vivo esophageal-vagal preparations with intact nerve endings in the esophagus. Antigen challenge significantly increased infiltrations of eosinophils and mast cells in the esophagus. TRPA1 agonist allyl isothiocyanate (AITC)-induced calcium influx in nodose and jugular neurons was significantly increased, and current densities in esophageal DiI-labeled nodose and jugular neurons were also significantly increased in antigen-challenged animals. Prolonged antigen challenge decreased esophageal epithelial barrier resistance, which allowed intraesophageal-infused AITC-activating nodose and jugular C fibers at their nerve endings. Collectively, these results demonstrated that prolonged antigen challenge sensitized TRPA1 in esophageal sensory neurons and afferent C fibers. This novel finding will help us to better understand the molecular mechanism underlying esophageal sensory and motor dysfunctions in EoE.
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Affiliation(s)
- Zhenyu Liu
- 1Division of Gastroenterology, Peking University Shenzhen Hospital, Shenzhen, China; ,2Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Youtian Hu
- 2Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Xiaoyun Yu
- 2Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Jiefeng Xi
- 3Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Xiaoming Fan
- 4Division of Gastroenterology and Hepatology, Jinshan Hospital of Fudan University, Shanghai, China
| | - Chung-Ming Tse
- 2Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Allen C. Myers
- 2Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Pankaj J. Pasricha
- 2Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Xingde Li
- 3Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Shaoyong Yu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland;
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Blackshaw LA. Transient receptor potential cation channels in visceral sensory pathways. Br J Pharmacol 2014; 171:2528-36. [PMID: 24641218 DOI: 10.1111/bph.12641] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 01/09/2014] [Accepted: 01/20/2014] [Indexed: 01/03/2023] Open
Abstract
The extensive literature on this subject is in direct contrast to the limited range of clinical uses for ligands of the transient receptor potential cation channels (TRPs) in diseases of the viscera. TRPV1 is the most spectacular example of this imbalance, as it is in other systems, but it is nonetheless the only TRP target that is currently targeted clinically in bladder sensory dysfunction. It is not clear why this discrepancy exists, but a likely answer is in the promiscuity of TRPs as sensors and transducers for environmental mechanical and chemical stimuli. This review first describes the different sensory pathways from the viscera, and on which nociceptive and non-nociceptive neurones within these pathways TRPs are expressed. They not only fulfil roles as both mechano- and chemo-sensors on visceral afferents, but also form an effector mechanism for cell activation after activation of GPCR and cytokine receptors. Their role may be markedly changed in diseased states, including chronic pain and inflammation. Pain presents the most obvious potential for further development of therapeutic interventions targeted at TRPs, but forms of inflammation are emerging as likely to benefit also. However, despite much basic research, we are still at the beginning of exploring such potential in visceral sensory pathways.
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Affiliation(s)
- L Ashley Blackshaw
- Wingate Institute for Neurogastroenterology, Centre for Digestive Diseases, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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Dusenkova S, Ru F, Surdenikova L, Nassenstein C, Hatok J, Dusenka R, Banovcin P, Kliment J, Tatar M, Kollarik M. The expression profile of acid-sensing ion channel (ASIC) subunits ASIC1a, ASIC1b, ASIC2a, ASIC2b, and ASIC3 in the esophageal vagal afferent nerve subtypes. Am J Physiol Gastrointest Liver Physiol 2014; 307:G922-30. [PMID: 25190475 PMCID: PMC4216991 DOI: 10.1152/ajpgi.00129.2014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Acid-sensing ion channels (ASICs) have been implicated in esophageal acid sensing and mechanotransduction. However, insufficient knowledge of ASIC subunit expression profile in esophageal afferent nerves hampers the understanding of their role. This knowledge is essential because ASIC subunits form heteromultimeric channels with distinct functional properties. We hypothesized that the esophageal putative nociceptive C-fiber nerves (transient receptor potential vanilloid 1, TRPV1-positive) express multiple ASIC subunits and that the ASIC expression profile differs between the nodose TRPV1-positive subtype developmentally derived from placodes and the jugular TRPV1-positive subtype derived from neural crest. We performed single cell RT-PCR on the vagal afferent neurons retrogradely labeled from the esophagus. In the guinea pig, nearly all (90%-95%) nodose and jugular esophageal TRPV1-positive neurons expressed ASICs, most often in a combination (65-75%). ASIC1, ASIC2, and ASIC3 were expressed in 65-75%, 55-70%, and 70%, respectively, of both nodose and jugular TRPV1-positive neurons. The ASIC1 splice variants ASIC1a and ASIC1b and the ASIC2 splice variant ASIC2b were similarly expressed in both nodose and jugular TRPV1-positive neurons. However, ASIC2a was found exclusively in the nodose neurons. In contrast to guinea pig, ASIC3 was almost absent from the mouse vagal esophageal TRPV1-positive neurons. However, ASIC3 was similarly expressed in the nonnociceptive TRPV1-negative (tension mechanoreceptors) neurons in both species. We conclude that the majority of esophageal vagal nociceptive neurons express multiple ASIC subunits. The placode-derived nodose neurons selectively express ASIC2a, known to substantially reduce acid sensitivity of ASIC heteromultimers. ASIC3 is expressed in the guinea pig but not in the mouse vagal esophageal TRPV1-positive neurons, indicating species differences in ASIC expression.
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Affiliation(s)
- Svetlana Dusenkova
- 1Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland; ,2Department of Pathophysiology, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia;
| | - Fei Ru
- 1Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Lenka Surdenikova
- 2Department of Pathophysiology, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia;
| | - Christina Nassenstein
- 1Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland; ,6Institute of Anatomy and Cell Biology-Cardiopulmonary Neurobiology, Justus-Liebig-University, Giessen, Germany
| | - Jozef Hatok
- 3Department of Biochemistry, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia;
| | - Robert Dusenka
- 3Department of Biochemistry, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia; ,4Department of Urology, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia;
| | - Peter Banovcin
- 5Department of Gastroenterology, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia;
| | - Jan Kliment
- 4Department of Urology, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia;
| | - Milos Tatar
- 2Department of Pathophysiology, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia;
| | - Marian Kollarik
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Pathophysiology, Comenius University in Bratislava, Jessenius Faculty of Medicine, Martin, Slovakia;
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26
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Yu X, Hu Y, Yu S. Effects of acid on vagal nociceptive afferent subtypes in guinea pig esophagus. Am J Physiol Gastrointest Liver Physiol 2014; 307:G471-8. [PMID: 24994852 PMCID: PMC4137112 DOI: 10.1152/ajpgi.00156.2014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Acid reflux-induced heartburn and noncardiac chest pain are processed peripherally by sensory nerve endings in the wall of the esophagus, but the underlying mechanism is still unclear. This study aims to determine the effects of acid on esophageal vagal nociceptive afferent subtypes. Extracellular single-unit recordings were performed in guinea pig vagal nodose or jugular C fiber neurons by using ex vivo esophageal-vagal preparations with intact nerve endings in the esophagus. We recorded action potentials (AP) of esophageal nodose or jugular C fibers evoked by acid perfusion and compared esophageal distension-evoked AP before and after acid perfusion. Acid perfusion for 30 min (pH range 7.4 to 5.8) did not evoke AP in nodose C fibers but significantly decreased their responses to esophageal distension, which could be recovered after washing out acid for 90 min. In jugular C fibers, acid perfusion not only evoked AP but also inhibited their responses to esophageal distension, which were not recovered after washing out acid for 120 min. Lower concentration of capsaicin perfusion mimicked acid-induced effects in nodose and jugular C fibers. Pretreatment with TRPV1 antagonist AMG9810, but not acid-sensing ion channel (ASIC) inhibitor amiloride, significantly inhibited acid-induced effects in nodose and jugular C fiber. These results demonstrate that esophageal vagal nociceptive afferent nerve subtypes display distinctive responses to acid. Acid activates jugular, but not nodose, C fibers and inhibits both of their responses to esophageal distension. These effects are mediated mainly through TRPV1. This inhibitory effect is a novel finding and may contribute to esophageal sensory/motor dysfunction in acid reflux diseases.
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Affiliation(s)
| | | | - Shaoyong Yu
- Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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27
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Farmer AD, Aziz Q. Mechanisms of visceral pain in health and functional gastrointestinal disorders. Scand J Pain 2014; 5:51-60. [PMID: 29913680 DOI: 10.1016/j.sjpain.2014.01.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 01/07/2014] [Indexed: 02/07/2023]
Abstract
Background and aims Chronic visceral pain is common both in patients with identifiable organic disease and also in those without any structural, biochemical or immunological abnormality such as in the functional gastrointestinal disorders (FGIDs). We aim to provide a contemporaneous summary of pathways involved in visceral nociception and how a variety of mechanisms may influence an individual's experience of visceral pain. Methods In this narrative review, we have brought together evidence through a detailed search of Medline in addition to using our experience and exposure to recent research developments from ourselves and other research groups. Results FGIDs are a heterogeneous group of disorders whose aetiology largely remains an enigma. The germane hypothesis for the genesis and maintenance of chronic visceral pain in FGIDs is the concept of visceral hypersensitivity. A number of peripheral and central mechanisms have been proposed to account for this epiphenomenon. In the periphery, inflammatory mediators activate and sensitize nociceptive afferent nerves by reducing their transduction thresholds and by inducing the expression and recruitment of hitherto silent nociceptors culminating in an increase in pain sensitivity at the site of injury known as primary hyperalgesia. Centrally, secondary hyperalgesia, defined as an increase in pain sensitivity in anatomically distinct sites, occurs at the level of the spinal dorsal horn. Moreover, the stress responsive physiological systems, genetic and psychological factors may modulate the experience of visceral pain. We also address some novel aetiological concepts in FGIDs, namely the gastrointestinal microbiota, connective tissue abnormalities and the gastrointestinal neuromuscular disorders. Firstly, the gastrointestinal microbiota is a diverse and dynamic ecosystem, that safeguards the host from external pathogens, aids in the metabolism of polysaccharides and lipids, modulates intestinal motility, in addition to modulating visceral perception. Secondly, connective tissue disorders, which traditionally have been considered to be confined largely to the musculoskeletal system, have an increasing evidence base demonstrating the presence of visceral manifestations. Since the sensorimotor apparatus of the GI tract is embedded within connective tissue it should not be surprising that such disorder may result in visceral pain and abnormal gut motility. Thirdly, gastrointestinal neuromuscular diseases refer to a heterogeneous group of disorders in which symptoms arise from impaired GI motor activity often manifesting as abnormal transit with or without radiological evidence of transient or persistent dilation of the viscera. Although a number of these are readily recognizable, such as achalasia or Hirschsprung's disease, the cause in a number of patients is not. An international working group has recently addressed this "gap", providing a comprehensive morphologically based diagnostic criteria. Conclusions/implications Although marked advances have been made in understanding the mechanisms that contribute to the development and maintenance of visceral pain, many interventions have failed to produce tangible improvement in patient outcomes. In the last part of this review we highlight an emerging approach that has allowed the definition and delineation of temporally stable visceral pain clusters, which may improve participant homogeneity in future studies, potentially facilitate stratification of treatment in FGID and lead to improvements in diagnostic criteria and outcomes.
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Affiliation(s)
- Adam D Farmer
- Centre for Digestive Diseases, Blizard Institute, Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine & Dentistry, Queen Mary University of London, London E1 2AJ, UK
| | - Qasim Aziz
- Centre for Digestive Diseases, Blizard Institute, Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine & Dentistry, Queen Mary University of London, London E1 2AJ, UK
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28
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Weijenborg PW, Bredenoord AJ. How reflux causes symptoms: reflux perception in gastroesophageal reflux disease. Best Pract Res Clin Gastroenterol 2013; 27:353-64. [PMID: 23998974 DOI: 10.1016/j.bpg.2013.06.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 06/11/2013] [Accepted: 06/23/2013] [Indexed: 02/07/2023]
Abstract
In gastroesophageal reflux disease (GERD) symptoms arise due to reflux of gastric content into the oesophagus. However, the relation between magnitude and onset of reflux and symptom generation in GERD patients is far from simple; gastroesophageal reflux occurs several times a day in everyone and the majority of reflux episodes remains asymptomatic. This review aims to address the question how reflux causes symptoms, focussing on factors leading to enhanced reflux perception. We will highlight esophageal sensitivity variance between subtypes of GERD, which is influenced by peripheral sensitization of primary afferents, central sensitization of spinal dorsal horn neurons, impaired mucosal barrier function and genetic factors. We will also discuss the contribution of specific refluxate characteristics to reflux perception, including acidity, and the role of bile, pepsin and gas and proximal extent. Further understanding of reflux perception might improve GERD treatment, especially in current partial responders to therapy.
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Affiliation(s)
- Pim W Weijenborg
- Dept. of Gastroenterology and Hepatology, Academic Medical Center Amsterdam, Meibergdreef 9, Postbus 22660, 1100 DD Amsterdam, The Netherlands.
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29
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Brozmanová M, Mazúrová L, Tatár M, Kollárik M. Evaluation of the effect of GABA(B) agonists on the vagal nodose C-fibers in the esophagus. Physiol Res 2013; 62:285-95. [PMID: 23489191 DOI: 10.33549/physiolres.932429] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Clinical studies showed that GABA(B) receptor agonists improve symptoms in patients with gastroesophageal reflux disease. One proposed mechanism of this effect is direct inhibition of the gastroesophageal vagal tension mechanosensors by GABA(B) agonists leading to reduction of reflux. In addition to tension mechanosensors, the vagal nodose ganglion supplies the esophagus with nociceptive C-fibers that likely contribute to impairment of esophageal reflex regulation in diseases. We hypothesized that GABA(B) agonists inhibit mechanically-induced activation of vagal esophageal nodose C-fibers in baseline and/or in sensitized state induced by inflammatory mediators. Ex vivo extracellular recordings were made from the esophageal nodose C-fibers in the isolated vagally-innervated guinea pig esophagus. We found that the selective GABA(B) agonist baclofen (100-300 microM) did not inhibit activation of esophageal nodose C-fibers evoked by esophageal distention (10-60 mmHg). The mechanical response of esophageal nodose C-fibers can be sensitized by different pathways including the stimulation of the histamine H(1) receptor and the stimulation the adenosine A(2A) receptor. Baclofen failed to inhibit mechanical sensitization of esophageal nodose C-fibers induced by histamine (100 microM) or the selective adenosine A(2A) receptor agonist CGS21680 (3 nM). Our data suggest that the direct mechanical inhibition of nodose C-fibers in the esophagus is unlikely to contribute to beneficial effects of GABA(B) agonists in patients with esophageal diseases.
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Affiliation(s)
- M Brozmanová
- Department of Pathophysiology, Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia.
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30
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Petho G, Reeh PW. Sensory and signaling mechanisms of bradykinin, eicosanoids, platelet-activating factor, and nitric oxide in peripheral nociceptors. Physiol Rev 2013; 92:1699-775. [PMID: 23073630 DOI: 10.1152/physrev.00048.2010] [Citation(s) in RCA: 191] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Peripheral mediators can contribute to the development and maintenance of inflammatory and neuropathic pain and its concomitants (hyperalgesia and allodynia) via two mechanisms. Activation or excitation by these substances of nociceptive nerve endings or fibers implicates generation of action potentials which then travel to the central nervous system and may induce pain sensation. Sensitization of nociceptors refers to their increased responsiveness to either thermal, mechanical, or chemical stimuli that may be translated to corresponding hyperalgesias. This review aims to give an account of the excitatory and sensitizing actions of inflammatory mediators including bradykinin, prostaglandins, thromboxanes, leukotrienes, platelet-activating factor, and nitric oxide on nociceptive primary afferent neurons. Manifestations, receptor molecules, and intracellular signaling mechanisms of the effects of these mediators are discussed in detail. With regard to signaling, most data reported have been obtained from transfected nonneuronal cells and somata of cultured sensory neurons as these structures are more accessible to direct study of sensory and signal transduction. The peripheral processes of sensory neurons, where painful stimuli actually affect the nociceptors in vivo, show marked differences with respect to biophysics, ultrastructure, and equipment with receptors and ion channels compared with cellular models. Therefore, an effort was made to highlight signaling mechanisms for which supporting data from molecular, cellular, and behavioral models are consistent with findings that reflect properties of peripheral nociceptive nerve endings. Identified molecular elements of these signaling pathways may serve as validated targets for development of novel types of analgesic drugs.
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Affiliation(s)
- Gábor Petho
- Pharmacodynamics Unit, Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Pécs, Pécs, Hungary
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31
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Arisawa T, Tahara T, Shiroeda H, Minato T, Matsue Y, Saito T, Fukuyama T, Otsuka T, Fukumura A, Nakamura M, Shibata T. Genetic polymorphisms of SCN10A are associated with functional dyspepsia in Japanese subjects. J Gastroenterol 2013; 48:73-80. [PMID: 22618805 DOI: 10.1007/s00535-012-0602-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 04/05/2012] [Indexed: 02/06/2023]
Abstract
BACKGROUND Visceral sensory impulses are transmitted via C-fibers from the gastrointestinal tract to the central nervous system. The tetrodotoxinresistant (TTX-r) sodium channel, Na(V) 1.8/SNS (sensory-neuron specific), encoded by SCN10A, has been identified on C-fibers. We attempted to clarify the association between functional dyspepsia (FD) and SCN10A non-synonymous polymorphisms (2884 A>G, 3218 C>T and 3275 T>C). METHODS The study was performed in 642 subjects (345 with no symptoms and 297 with FD). We employed a multiplex polymerase chain reaction single-strand confirmation polymorphism (PCR-SSCP) method to detect the gene polymorphisms. RESULTS The 3218 CC homozygotes had a reduced risk for the development of FD [odds ratio (OR) 0.589; 95 % confidence interval (CI) 0.402-0.864; p = 0.0067]. In addition, both 2884 A>G and 3275 T>C, which were in linkage disequilibrium, were also associated with the development of FD (p = 0.039 and 0.028, respectively). Each 2884 G carrier, 3218 CC homozygote, and 3275 C carrier had a reduced risk for the development of both epigastric pain syndrome (EPS) and postprandial distress syndrome (PDS). The subjects with the 2884 G allele, 3275 C allele, and no 3218 T allele had a reduced risk for FD (OR 0.618; 95 % CI 0.448-0.853; p = 0.0034). This haplotype was associated with a reduced risk for both EPS and PDS (p = 0.0011 and 0.0056, respectively). In addition, there was a significant association between FD and this haplotype in Helicobacter pylori-negative subjects (OR 0.463; 95 % CI 0279-0.9768; p = 0.0029). CONCLUSION We conclude that genetic polymorphisms of SCN10A are closely associated with FD (both EPS and PDS), especially in H. pylori-negative subjects, in Japanese.
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Affiliation(s)
- Tomiyasu Arisawa
- Department of Gastroenterology, Kanazawa Medical University, 1-1 Daigaku, Uchinada-machi, Ishikawa, 920-0293, Japan.
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Lin YJ, Lin YS, Lai CJ, Yuan ZF, Ruan T, Kou YR. Perivagal antagonist treatment in rats selectively blocks the reflex and afferent responses of vagal lung C fibers to intravenous agonists. J Appl Physiol (1985) 2012; 114:361-70. [PMID: 23221955 DOI: 10.1152/japplphysiol.00977.2012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The terminals of vagal lung C fibers (VLCFs) express various types of pharmacological receptors that are important to the elicitation of airway reflexes and the development of airway hypersensitivity. We investigated the blockade of the reflex and afferent responses of VLCFs to intravenous injections of agonists using perivagal treatment with antagonists (PAT) targeting the transient receptor potential vanilloid 1, P2X, and 5-HT(3) receptors in anesthetized rats. Blockading these responses via perivagal capsaicin treatment (PCT), which blocks the neural conduction of C fibers, was also studied. We used capsaicin, α,β-methylene-ATP, and phenylbiguanide as the agonists, and capsazepine, iso-pyridoxalphosphate-6-azophenyl-2',5'-disulfonate, and tropisetron as the antagonists of transient receptor potential vanilloid 1, P2X, and 5-HT(3) receptors, respectively. We found that each of the PATs abolished the VLCF-mediated reflex apnea evoked by the corresponding agonist, while having no effect on the response to other agonists. Perivagal vehicle treatment failed to produce any such blockade. These blockades had partially recovered at 3 h after removal of the PATs. In contrast, PCT abolished the reflex apneic response to all three agonists. Both PATs and PCT did not affect the myelinated afferent-mediated apneic response to lung inflation. Consistently, our electrophysiological studies revealed that each of the PATs prevented the VLCF responses to the corresponding agonist, but not to any other agonist. PCT inevitably prevented the VLCF responses to all three agonists. Thus these PATs selectively blocked the stimulatory action of corresponding agonists on the VLCF terminals via mechanisms that are distinct from those of PCT. PAT may become a novel intervention for studying the pharmacological modulation of VLCFs.
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Affiliation(s)
- Yu-Jung Lin
- Institute of Physiology, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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33
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Surdenikova L, Ru F, Nassenstein C, Tatar M, Kollarik M. The neural crest- and placodes-derived afferent innervation of the mouse esophagus. Neurogastroenterol Motil 2012; 24:e517-25. [PMID: 22937918 DOI: 10.1111/nmo.12002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
BACKGROUND The mouse is an invaluable model for mechanistic studies of esophageal nerves, but the afferent innervation of the mouse esophagus is incompletely understood. Vagal afferent neurons are derived from two embryonic sources: neural crest and epibranchial placodes. We hypothesized that both neural crest and placodes contribute to the TRPV1-positive (potentially nociceptive) vagal innervation of the mouse esophagus. METHODS Vagal jugular/nodose ganglion (JNG) and spinal dorsal root ganglia (DRG) neurons were retrogradely labeled from the cervical esophagus. Single cell RT-PCR was performed on the labeled neurons. KEY RESULTS In the Wnt1Cre/R26R mice expressing a reporter in the neural crest-derived cells we found that both the neural crest- and the placodes-derived vagal JNG neurons innervate the mouse esophagus. In the wild-type mouse the esophageal vagal JNG TRPV1-positive neurons segregated into two subsets: putative neural crest-derived purinergic receptor P2X(2) -negative/preprotachykinin-A (PPT-A)-positive subset and putative placodes-derived P2X(2) -positive/PPTA-negative subset. These subsets also segregated by the expression of TrkA and GFRα(3) in the putative neural crest-derived subset, and TrkB in the putative placodes-derived subset. The TRPV1-positive esophageal DRG neurons had the phenotype similar to the vagal putative neural crest-derived subset. CONCLUSIONS & INFERENCES The TRPV1-positive (potentially nociceptive) vagal afferent neurons innervating the mouse esophagus originate from both neural crest and placodes. The expression profile of the receptors for neurotrophic factors is similar between the neural crest-derived vagal and spinal nociceptors, but distinct from the vagal placodes-derived nociceptors.
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Affiliation(s)
- L Surdenikova
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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34
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The transient receptor potential channel TRPA1: from gene to pathophysiology. Pflugers Arch 2012; 464:425-58. [DOI: 10.1007/s00424-012-1158-z] [Citation(s) in RCA: 262] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 09/06/2012] [Accepted: 09/06/2012] [Indexed: 12/13/2022]
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35
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Yu S, Ouyang A. Effect of synthetic cationic protein on mechanoexcitability of vagal afferent nerve subtypes in guinea pig esophagus. Am J Physiol Gastrointest Liver Physiol 2011; 301:G1052-8. [PMID: 21960520 PMCID: PMC3233783 DOI: 10.1152/ajpgi.00015.2011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Eosinophilic esophagitis is characterized by increased infiltration and degranulation of eosinophils in the esophagus. Whether eosinophil-derived cationic proteins regulate esophageal sensory nerve function is still unknown. Using synthetic cationic protein to investigate such effect, we performed extracellular recordings from vagal nodose or jugular neurons in ex vivo esophageal-vagal preparations with intact nerve endings in the esophagus. Nerve excitabilities were determined by comparing action potentials evoked by esophageal distensions before and after perfusion of synthetic cationic protein poly-L-lysine (PLL) with or without pretreatment with poly-L-glutamic acid (PLGA), which neutralized cationic charges of PLL. Perfusion with PLL did not evoke action potentials in esophageal nodose C fibers but increased their responses to esophageal distension. This potentiation effect lasted for 30 min after washing out of PLL. Pretreatment with PLGA significantly inhibited PLL-induced mechanohyperexcitability of esophageal nodose C fibers. In esophageal nodose Aδ fibers, perfusion with PLL did not evoke action potentials. In contrast to nodose C fibers, both the spontaneous discharges and the responses to esophageal distension in nodose Aδ fibers were decreased by perfusion with PLL, which can be restored after washing out PLL for 30-60 min. Pretreatment with PLGA attenuated PLL-induced decrease in spontaneous discharge and mechanoexcitability of esophageal nodose Aδ fibers. In esophageal jugular C fibers, PLL neither evoked action potentials nor changed their responses to esophageal distension. Collectively, these data demonstrated that synthetic cationic protein did not evoke action potential discharges of esophageal vagal afferents but had distinctive sensitization effects on their responses to esophageal distension.
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Affiliation(s)
- Shaoyong Yu
- 1Department of Medicine, University of Michigan Medical School, Ann Arbor, Michigan; and
| | - Ann Ouyang
- 2Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania
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Andrade EL, Meotti FC, Calixto JB. TRPA1 antagonists as potential analgesic drugs. Pharmacol Ther 2011; 133:189-204. [PMID: 22119554 DOI: 10.1016/j.pharmthera.2011.10.008] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 10/29/2011] [Indexed: 12/16/2022]
Abstract
The necessity of safe and effective treatments for chronic pain has intensified the search for new analgesic drugs. In the last few years, members of a closely-related family of ion channels, called transient receptor potential (TRP) have been identified in different cell types and their functions in physiological and pathological conditions have been characterized. The transient receptor potential ankyrin 1 (TRPA1), originally called ANKTM1 (ankyrin-like with transmembrane domains protein 1), is a molecule that has been conserved in different species during evolution; TRPA1 is a cation channel that functions as a cellular sensor, detecting mechanical, chemical and thermal stimuli, being a component of neuronal, epithelial, blood and smooth muscle tissues. In mammals, TRPA1 is largely expressed in primary sensory neurons that mediate somatosensory processes and nociceptive transmission. Recent studies have described the role of TRPA1 in inflammatory and neuropathic pain. However, its participation in cold sensation has not been agreed in different studies. In this review, we focus on data that support the relevance of the activation and blockade of TRPA1 in pain transmission, as well as the mechanisms underlying its activation and modulation by exogenous and endogenous stimuli. We also discuss recent advances in the search for new analgesic medicines targeting the TRPA1 channel.
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Affiliation(s)
- E L Andrade
- Departamento de Farmacologia, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
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Brozmanova M, Ru F, Surdenikova L, Mazurova L, Taylor-Clark T, Kollarik M. Preferential activation of the vagal nodose nociceptive subtype by TRPA1 agonists in the guinea pig esophagus. Neurogastroenterol Motil 2011; 23:e437-45. [PMID: 21883700 PMCID: PMC3175634 DOI: 10.1111/j.1365-2982.2011.01768.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND The TRPA1 receptor is directly activated by a wide range of chemicals including many endogenous molecules relevant for esophageal pathophysiology. We addressed the hypothesis that the TRPA1 agonists differentially activate esophageal nociceptive subtypes depending on their embryological source (neural crest or epibranchial placodes). METHODS Single cell RT-PCR and whole cell patch clamp recordings were performed on the vagal neurons retrogradely labeled from the guinea pig esophagus. Extracellular recordings were made in the isolated innervated esophagus preparation ex vivo. KEY RESULTS Single cell RT-PCR revealed that the majority of the nodose (placodes-derived) and jugular (neural crest-derived) TRPV1-positive esophageal nociceptors express TRPA1. Single fiber recording showed that the TRPA1 agonists allyl-isothiocyanate (AITC) and cinnamaldehyde were effective in inducing robust action potential discharge in the nerve terminals of nodose nociceptors, but had far less effect in jugular nociceptors (approximately fivefold less). Higher efficacy of the TRPA1 agonists to activate nodose nociceptors was confirmed in the isolated esophagus-labeled vagal neurons in the whole cell patch clamp studies. Similarly to neural crest-derived vagal jugular nociceptors, the spinal DRG nociceptors that are also neural crest-derived were only modestly activated by allyl-isothiocyanate. CONCLUSIONS & INFERENCES We conclude that the TRPA1 agonists are substantially more effective activators of the placodes-derived than the neural crest-derived esophageal nociceptors. Our data predict that in esophageal diseases the presence of endogenous TRPA1 activators will be preferentially signaled by the vagal nodose nociceptors.
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Affiliation(s)
- M Brozmanova
- Pathophysiology, Jessenius Medical School, Comenius University, Martin, Slovakia
| | - F Ru
- Medicine, The Johns Hopkins School of Medicine, Baltimore, MD
| | - L Surdenikova
- Pathophysiology, Jessenius Medical School, Comenius University, Martin, Slovakia,Medicine, The Johns Hopkins School of Medicine, Baltimore, MD
| | - L Mazurova
- Pathophysiology, Jessenius Medical School, Comenius University, Martin, Slovakia
| | - T Taylor-Clark
- Medicine, The Johns Hopkins School of Medicine, Baltimore, MD
| | - M. Kollarik
- Medicine, The Johns Hopkins School of Medicine, Baltimore, MD
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Holzer P. TRP channels in the digestive system. Curr Pharm Biotechnol 2011; 12:24-34. [PMID: 20932260 DOI: 10.2174/138920111793937862] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 05/09/2010] [Indexed: 12/26/2022]
Abstract
Several of the 28 mammalian transient receptor potential (TRP) channel subunits are expressed throughout the alimentary canal where they play important roles in taste, chemo- and mechanosensation, thermoregulation, pain and hyperalgesia, mucosal function and homeostasis, control of motility by neurons, interstitial cells of Cajal and muscle cells, and vascular function. While the implications of some TRP channels, notably TRPA1, TRPC4, TRPM5, TRPM6, TRPM7, TRPV1, TRPV4, and TRPV6, have been investigated in much detail, the understanding of other TRP channels in their relevance to digestive function lags behind. The polymodal chemo- and mechanosensory function of TRPA1, TRPM5, TRPV1 and TRPV4 is particularly relevant to the alimentary canal whose digestive and absorptive function depends on the surveillance and integration of many chemical and physical stimuli. TRPV5 and TRPV6 as well as TRPM6 and TRPM7 appear to be essential for the absorption of Ca(2+) and Mg(2+), respectively, while TRPM7 appears to contribute to the pacemaker activity of the interstitial cells of Cajal, and TRPC4 transduces smooth muscle contraction evoked by muscarinic acetylcholine receptor activation. The implication of some TRP channels in pathological processes has raised enormous interest in exploiting them as a therapeutic target. This is particularly true for TRPV1, TRPV4 and TRPA1, which may be targeted for the treatment of several conditions of chronic abdominal pain. Consequently, blockers of these TRP channels have been developed, and their clinical usefulness has yet to be established.
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Affiliation(s)
- Peter Holzer
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitátsplatz 4, A-8010 Graz, Austria.
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Holzer P. Transient receptor potential (TRP) channels as drug targets for diseases of the digestive system. Pharmacol Ther 2011; 131:142-70. [PMID: 21420431 PMCID: PMC3107431 DOI: 10.1016/j.pharmthera.2011.03.006] [Citation(s) in RCA: 172] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 03/01/2011] [Indexed: 12/12/2022]
Abstract
Approximately 20 of the 30 mammalian transient receptor potential (TRP) channel subunits are expressed by specific neurons and cells within the alimentary canal. They subserve important roles in taste, chemesthesis, mechanosensation, pain and hyperalgesia and contribute to the regulation of gastrointestinal motility, absorptive and secretory processes, blood flow, and mucosal homeostasis. In a cellular perspective, TRP channels operate either as primary detectors of chemical and physical stimuli, as secondary transducers of ionotropic or metabotropic receptors, or as ion transport channels. The polymodal sensory function of TRPA1, TRPM5, TRPM8, TRPP2, TRPV1, TRPV3 and TRPV4 enables the digestive system to survey its physical and chemical environment, which is relevant to all processes of digestion. TRPV5 and TRPV6 as well as TRPM6 and TRPM7 contribute to the absorption of Ca²⁺ and Mg²⁺, respectively. TRPM7 participates in intestinal pacemaker activity, and TRPC4 transduces muscarinic acetylcholine receptor activation to smooth muscle contraction. Changes in TRP channel expression or function are associated with a variety of diseases/disorders of the digestive system, notably gastro-esophageal reflux disease, inflammatory bowel disease, pain and hyperalgesia in heartburn, functional dyspepsia and irritable bowel syndrome, cholera, hypomagnesemia with secondary hypocalcemia, infantile hypertrophic pyloric stenosis, esophageal, gastrointestinal and pancreatic cancer, and polycystic liver disease. These implications identify TRP channels as promising drug targets for the management of a number of gastrointestinal pathologies. As a result, major efforts are put into the development of selective TRP channel agonists and antagonists and the assessment of their therapeutic potential.
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Affiliation(s)
- Peter Holzer
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, A-8010 Graz, Austria.
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Ru F, Surdenikova L, Brozmanova M, Kollarik M. Adenosine-induced activation of esophageal nociceptors. Am J Physiol Gastrointest Liver Physiol 2011; 300:G485-93. [PMID: 21148396 PMCID: PMC3064123 DOI: 10.1152/ajpgi.00361.2010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Clinical studies implicate adenosine acting on esophageal nociceptive pathways in the pathogenesis of noncardiac chest pain originating from the esophagus. However, the effect of adenosine on esophageal afferent nerve subtypes is incompletely understood. We addressed the hypothesis that adenosine selectively activates esophageal nociceptors. Whole cell perforated patch-clamp recordings and single-cell RT-PCR analysis were performed on the primary afferent neurons retrogradely labeled from the esophagus in the guinea pig. Extracellular recordings were made from the isolated innervated esophagus. In patch-clamp studies, adenosine evoked activation (inward current) in a majority of putative nociceptive (capsaicin-sensitive) vagal nodose, vagal jugular, and spinal dorsal root ganglia (DRG) neurons innervating the esophagus. Single-cell RT-PCR analysis indicated that the majority of the putative nociceptive (transient receptor potential V1-positive) neurons innervating the esophagus express the adenosine receptors. The neural crest-derived (spinal DRG and vagal jugular) esophageal nociceptors expressed predominantly the adenosine A(1) receptor while the placodes-derived vagal nodose nociceptors expressed the adenosine A(1) and/or A(2A) receptors. Consistent with the studies in the cell bodies, adenosine evoked activation (overt action potential discharge) in esophageal nociceptive nerve terminals. Furthermore, the neural crest-derived jugular nociceptors were activated by the selective A(1) receptor agonist CCPA, and the placodes-derived nodose nociceptors were activated by CCPA and/or the selective adenosine A(2A) receptor CGS-21680. In contrast to esophageal nociceptors, adenosine failed to stimulate the vagal esophageal low-threshold (tension) mechanosensors. We conclude that adenosine selectively activates esophageal nociceptors. Our data indicate that the esophageal neural crest-derived nociceptors can be activated via the adenosine A(1) receptor while the placodes-derived esophageal nociceptors can be activated via A(1) and/or A(2A) receptors. Direct activation of esophageal nociceptors via adenosine receptors may contribute to the symptoms in esophageal diseases.
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Affiliation(s)
- F. Ru
- 1Department of Medicine, The Johns Hopkins School of Medicine, Baltimore, Maryland; and
| | - L. Surdenikova
- 2Department of Pathophysiology, Jessenius Medical School, Comenius University, Martin, Slovakia
| | - M. Brozmanova
- 2Department of Pathophysiology, Jessenius Medical School, Comenius University, Martin, Slovakia
| | - M. Kollarik
- 1Department of Medicine, The Johns Hopkins School of Medicine, Baltimore, Maryland; and
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Boesmans W, Owsianik G, Tack J, Voets T, Vanden Berghe P. TRP channels in neurogastroenterology: opportunities for therapeutic intervention. Br J Pharmacol 2011; 162:18-37. [PMID: 20804496 PMCID: PMC3012403 DOI: 10.1111/j.1476-5381.2010.01009.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 07/02/2010] [Accepted: 08/17/2010] [Indexed: 12/14/2022] Open
Abstract
The members of the superfamily of transient receptor potential (TRP) cation channels are involved in a plethora of cellular functions. During the last decade, a vast amount of evidence is accumulating that attributes an important role to these cation channels in different regulatory aspects of the alimentary tract. In this review we discuss the expression patterns and roles of TRP channels in the regulation of gastrointestinal motility, enteric nervous system signalling and visceral sensation, and provide our perspectives on pharmacological targeting of TRPs as a strategy to treat various gastrointestinal disorders. We found that the current knowledge about the role of some members of the TRP superfamily in neurogastroenterology is rather limited, whereas the function of other TRP channels, especially of those implicated in smooth muscle cell contractility (TRPC4, TRPC6), visceral sensitivity and hypersensitivity (TRPV1, TRPV4, TRPA1), tends to be well established. Compared with expression data, mechanistic information about TRP channels in intestinal pacemaking (TRPC4, TRPC6, TRPM7), enteric nervous system signalling (TRPCs) and enteroendocrine cells (TRPM5) is lacking. It is clear that several different TRP channels play important roles in the cellular apparatus that controls gastrointestinal function. They are involved in the regulation of gastrointestinal motility and absorption, visceral sensation and visceral hypersensitivity. TRP channels can be considered as interesting targets to tackle digestive diseases, motility disorders and visceral pain. At present, TRPV1 antagonists are under development for the treatment of heartburn and visceral hypersensitivity, but interference with other TRP channels is also tempting. However, their role in gastrointestinal pathophysiology first needs to be further elucidated.
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Affiliation(s)
- Werend Boesmans
- TARGID – Translational Research Center for Gastrointestinal DisordersKULeuven, Leuven, Belgium
| | | | - Jan Tack
- TARGID – Translational Research Center for Gastrointestinal DisordersKULeuven, Leuven, Belgium
| | - Thomas Voets
- Laboratory of Ion Channel ResearchKULeuven, Leuven, Belgium
| | - Pieter Vanden Berghe
- TARGID – Translational Research Center for Gastrointestinal DisordersKULeuven, Leuven, Belgium
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42
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Scientific Opinion on the safety of allyl isothiocyanate for the proposed uses as a food additive. EFSA J 2010. [DOI: 10.2903/j.efsa.2010.1943] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Koba S, Hayes SG, Sinoway LI. Transient receptor potential A1 channel contributes to activation of the muscle reflex. Am J Physiol Heart Circ Physiol 2010; 300:H201-13. [PMID: 21076024 DOI: 10.1152/ajpheart.00547.2009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study was undertaken to elucidate the role played by transient receptor potential A1 channels (TRPA1) in activating the muscle reflex, a sympathoexcitatory drive originating in contracting muscle. First, we tested the hypothesis that stimulation of the TRPA1 located on muscle afferents reflexly increases sympathetic nerve activity. In decerebrate rats, allyl isothiocyanate, a TRPA1 agonist, was injected intra-arterially into the hindlimb muscle circulation. This led to a 33% increase in renal sympathetic nerve activity (RSNA). The effect of allyl isothiocyanate was a reflex because the response was prevented by sectioning the sciatic nerve. Second, we tested the hypothesis that blockade of TRPA1 reduces RSNA response to contraction. Thirty-second continuous static contraction of the hindlimb muscles, induced by electrical stimulation of the peripheral cut ends of L(4) and L(5) ventral roots, increased RSNA and blood pressure. The integrated RSNA during contraction was reduced by HC-030031, a TRPA1 antagonist, injected intra-arterially (163 ± 24 vs. 95 ± 21 arbitrary units, before vs. after HC-030031, P < 0.05). Third, we attempted to identify potential endogenous stimulants of TRPA1, responsible for activating the muscle reflex. Increases in RSNA in response to injection into the muscle circulation of arachidonic acid, bradykinin, and diprotonated phosphate, which are metabolic by-products of contraction and stimulants of muscle afferents during contraction, were reduced by HC-030031. These observations suggest that the TRPA1 located on muscle afferents is part of the muscle reflex and further support the notion that arachidonic acid metabolites, bradykinin, and diprotonated phosphate are candidates for endogenous agonists of TRPA1.
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Affiliation(s)
- Satoshi Koba
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA.
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Miwa H, Kondo T, Oshima T, Fukui H, Tomita T, Watari J. Esophageal sensation and esophageal hypersensitivity - overview from bench to bedside. J Neurogastroenterol Motil 2010; 16:353-62. [PMID: 21103417 PMCID: PMC2978388 DOI: 10.5056/jnm.2010.16.4.353] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 08/13/2010] [Accepted: 08/19/2010] [Indexed: 12/19/2022] Open
Abstract
Noxious stimuli in the esophagus activate nociceptive receptors on esophageal mucosa, such as transient receptor potential, acid-sensing ion channel and the P2X family, a family of ligand-gated ion channels responsive to ATP, and this generates signals that are transmitted to the central nervous system via either spinal nerves or vagal nerves, resulting in esophageal sensation. Among the noxious stimuli, gastric acid and other gastric contents are clinically most important, causing typical reflux symptoms such as heartburn and regurgitation. A conventional acid penetration theory has been used to explain the mechanism of heartburn, but much recent evidence does not support this theory. Therefore, it may be necessary to approach the causes of heartburn symptoms from a new conceptual framework. Hypersensitivity of the esophagus, like that of other visceral organs, includes peripheral, central and probably psychosocial factor-mediated hypersensitivity, and is known to play crucial roles in the pathoegenesis of nonerosive reflux disease, functional heartburn and non-cardiac chest pain. There also are esophagitis patients who do not perceive typical symptoms. This condition is known as silent gastroesophageal reflux disease. Although the pathogenesis of silent gastroesophageal reflux disease is still not known, hyposensitivity to reflux of acid may possibly explain the condition.
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Affiliation(s)
- Hiroto Miwa
- Division of Upper Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Hyogo, Japan
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45
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Mitrovic M, Shahbazian A, Bock E, Pabst MA, Holzer P. Chemo-nociceptive signalling from the colon is enhanced by mild colitis and blocked by inhibition of transient receptor potential ankyrin 1 channels. Br J Pharmacol 2010; 160:1430-42. [PMID: 20590633 DOI: 10.1111/j.1476-5381.2010.00794.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Transient receptor potential ankyrin 1 (TRPA1) channels are expressed by primary afferent neurones and activated by irritant chemicals including allyl isothiocyanate (AITC). Here we investigated whether intracolonic AITC causes afferent input to the spinal cord and whether this response is modified by mild colitis, morphine or a TRPA1 channel blocker. EXPERIMENTAL APPROACH One hour after intracolonic administration of AITC to female mice, afferent signalling was visualized by expression of c-Fos in laminae I-II(o) of the spinal dorsal horn at sacral segment S1. Mild colitis was induced by dextran sulphate sodium (DSS) added to drinking water for 1 week. KEY RESULTS Relative to vehicle, AITC (2%) increased expression of c-Fos in the spinal cord. Following induction of mild colitis by DSS (2%), spinal c-Fos responses to AITC, but not vehicle, were augmented by 41%. Colonic inflammation was present (increased myeloperoxidase content and disease activity score), whereas colonic histology, locomotion, feeding and drinking remained unchanged. Morphine (10 mg.kg(-1)) or the TRPA1 channel blocker HC-030031 (300 mg.kg(-1)) inhibited the spinal c-Fos response to AITC, in control and DSS-pretreated animals, whereas the response to intracolonic capsaicin (5%) was blocked by morphine but not HC-030031. CONCLUSIONS AND IMPLICATIONS Activation of colonic TRPA1 channels is signalled to the spinal cord. Mild colitis enhanced this afferent input that, as it is sensitive to morphine, is most likely of a chemonociceptive nature. As several irritant chemicals can be present in chyme, TRPA1 channels may mediate several gastrointestinal pain conditions.
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Affiliation(s)
- Martina Mitrovic
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Graz, Austria
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Sensory detection and responses to toxic gases: mechanisms, health effects, and countermeasures. Ann Am Thorac Soc 2010; 7:269-77. [PMID: 20601631 DOI: 10.1513/pats.201001-004sm] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The inhalation of reactive gases and vapors can lead to severe damage of the airways and lung, compromising the function of the respiratory system. Exposures to oxidizing, electrophilic, acidic, or basic gases frequently occur in occupational and ambient environments. Corrosive gases and vapors such as chlorine, phosgene, and chloropicrin were used as warfare agents and in terrorist acts. Chemical airway exposures are detected by the olfactory, gustatory, and nociceptive sensory systems that initiate protective physiological and behavioral responses. This review focuses on the role of airway nociceptive sensory neurons in chemical sensing and discusses the recent discovery of neuronal receptors for reactive chemicals. Using physiological, imaging, and genetic approaches, Transient Receptor Potential (TRP) ion channels in sensory neurons were shown to respond to a wide range of noxious chemical stimuli, initiating pain, respiratory depression, cough, glandular secretions, and other protective responses. TRPA1, a TRP ion channel expressed in chemosensory C-fibers, is activated by almost all oxidizing and electrophilic chemicals, including chlorine, acrolein, tear gas agents, and methyl isocyanate, the highly noxious chemical released in the Bhopal disaster. Chemicals likely activate TRPA1 through covalent protein modification. Animal studies using TRPA1 antagonists or TRPA1-deficient mice confirmed the role of TRPA1 in chemically induced respiratory reflexes, pain, and inflammation in vivo. New research shows that sensory neurons are not merely passive sensors of chemical exposures. Sensory channels such as TRPA1 are essential for maintenance of airway inflammation in asthma and may contribute to the progression of airway injury following high-level chemical exposures.
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Identifying the Ion Channels Responsible for Signaling Gastro-Intestinal Based Pain. Pharmaceuticals (Basel) 2010; 3:2768-2798. [PMID: 27713376 PMCID: PMC4034097 DOI: 10.3390/ph3092768] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 08/05/2010] [Accepted: 08/20/2010] [Indexed: 12/20/2022] Open
Abstract
We are normally unaware of the complex signalling events which continuously occur within our internal organs. Most of us only become cognisant when sensations of hunger, fullness, urgency or gas arise. However, for patients with organic and functional bowel disorders pain is an unpleasant and often debilitating reminder. Furthermore, chronic pain still represents a large unmet need for clinical treatment. Consequently, chronic pain has a considerable economic impact on health care systems and the afflicted individuals. In order to address this need we must understand how symptoms are generated within the gut, the molecular pathways responsible for generating these signals and how this process changes in disease states.
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48
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Zhao H, Sprunger LK, Simasko SM. Expression of transient receptor potential channels and two-pore potassium channels in subtypes of vagal afferent neurons in rat. Am J Physiol Gastrointest Liver Physiol 2010; 298:G212-21. [PMID: 19959819 PMCID: PMC2822499 DOI: 10.1152/ajpgi.00396.2009] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Vagal afferent neurons relay important information regarding the control of the gastrointestinal system. However, the ionic mechanisms that underlie vagal activation induced by sensory inputs are not completely understood. We postulate that transient receptor potential (TRP) channels and/or two-pore potassium (K2p) channels are targets for activating vagal afferents. In this study we explored the distribution of these channels in vagal afferents by quantitative PCR after a capsaicin treatment to eliminate capsaicin-sensitive neurons, and by single-cell PCR measurements in vagal afferent neurons cultured after retrograde labeling from the stomach or duodenum. We found that TRPC1/3/5/6, TRPV1-4, TRPM8, TRPA1, TWIK2, TRAAK, TREK1, and TASK1/2 were all present in rat nodose ganglia. Both lesion results and single-cell PCR results suggested that TRPA1 and TRPC1 were preferentially expressed in neurons that were either capsaicin sensitive or TRPV1 positive. Expression of TRPM8 varied dynamically after various manipulations, which perhaps explains the disparate results obtained by different investigators. Last, we also examined ion channel distribution with the A-type CCK receptor (CCK-R(A)) and found there was a significant preference for neurons that express TRAAK to also express CCK-R(A), especially in gut-innervating neurons. These findings, combined with findings from prior studies, demonstrated that background conductances such as TRPC1, TRPA1, and TRAAK are indeed differentially distributed in the nodose ganglia, and not only do they segregate with specific markers, but the degree of overlap is also dependent on the innervation target.
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Affiliation(s)
- Huan Zhao
- Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, WashingtonState University, Pullman, WA 99164, USA.
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Brierley SM, Hughes PA, Page AJ, Kwan KY, Martin CM, O’Donnell TA, Cooper NJ, Harrington AM, Adam B, Liebregts T, Holtmann G, Corey DP, Rychkov GY, Blackshaw LA. The ion channel TRPA1 is required for normal mechanosensation and is modulated by algesic stimuli. Gastroenterology 2009; 137:2084-2095.e3. [PMID: 19632231 PMCID: PMC2789877 DOI: 10.1053/j.gastro.2009.07.048] [Citation(s) in RCA: 204] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 06/19/2009] [Accepted: 07/15/2009] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS The transient receptor potential (TRP) channel family includes transducers of mechanical and chemical stimuli for visceral sensory neurons. TRP ankyrin 1 (TRPA1) is implicated in inflammatory pain; it interacts with G-protein-coupled receptors, but little is known about its role in the gastrointestinal (GI) tract. Sensory information from the GI tract is conducted via 5 afferent subtypes along 3 pathways. METHODS Nodose and dorsal root ganglia whose neurons innnervate 3 different regions of the GI tract were analyzed from wild-type and TRPA1(-/-) mice using quantitative reverse-transcription polymerase chain reaction, retrograde labeling, and in situ hybridization. Distal colon sections were analyzed by immunohistochemistry. In vitro electrophysiology and pharmacology studies were performed, and colorectal distension and visceromotor responses were measured. Colitis was induced by administration of trinitrobenzene sulphonic acid. RESULTS TRPA1 is required for normal mechano- and chemosensory function in specific subsets of vagal, splanchnic, and pelvic afferents. The behavioral responses to noxious colonic distension were substantially reduced in TRPA1(-/-) mice. TRPA1 agonists caused mechanical hypersensitivity, which increased in mice with colitis. Colonic afferents were activated by bradykinin and capsaicin, which mimic effects of tissue damage; wild-type and TRPA1(-/-) mice had similar direct responses to these 2 stimuli. After activation by bradykinin, wild-type afferents had increased mechanosensitivity, whereas, after capsaicin exposure, mechanosensitivity was reduced: these changes were absent in TRPA1(-/-) mice. No interaction between protease-activated receptor-2 and TRPA1 was evident. CONCLUSIONS These findings demonstrate a previously unrecognized role for TRPA1 in normal and inflamed mechanosensory function and nociception within the viscera.
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Affiliation(s)
- Stuart M. Brierley
- Nerve-Gut Research Laboratory, Department of Gastroenterology & Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA 5000, Discipline of Physiology, School of Molecular and Biomedical Sciences, The University of Adelaide, Adelaide, South Australia, AUSTRALIA 5000
| | - Patrick A. Hughes
- Nerve-Gut Research Laboratory, Department of Gastroenterology & Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA 5000, Discipline of Physiology, School of Molecular and Biomedical Sciences, The University of Adelaide, Adelaide, South Australia, AUSTRALIA 5000
| | - Amanda J. Page
- Nerve-Gut Research Laboratory, Department of Gastroenterology & Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA 5000, Discipline of Physiology, School of Molecular and Biomedical Sciences, The University of Adelaide, Adelaide, South Australia, AUSTRALIA 5000, Discipline of Medicine, The University of Adelaide, Adelaide, South Australia, AUSTRALIA 5000
| | - Kelvin Y. Kwan
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, USA, 02115
| | - Christopher M. Martin
- Nerve-Gut Research Laboratory, Department of Gastroenterology & Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA 5000
| | - Tracey A. O’Donnell
- Nerve-Gut Research Laboratory, Department of Gastroenterology & Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA 5000
| | - Nicole J. Cooper
- Nerve-Gut Research Laboratory, Department of Gastroenterology & Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA 5000
| | - Andrea M. Harrington
- Nerve-Gut Research Laboratory, Department of Gastroenterology & Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA 5000
| | - Birgit Adam
- Nerve-Gut Research Laboratory, Department of Gastroenterology & Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA 5000
| | - Tobias Liebregts
- Nerve-Gut Research Laboratory, Department of Gastroenterology & Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA 5000
| | - Gerald Holtmann
- Nerve-Gut Research Laboratory, Department of Gastroenterology & Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA 5000, Discipline of Medicine, The University of Adelaide, Adelaide, South Australia, AUSTRALIA 5000
| | - David P. Corey
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, USA, 02115
| | - Grigori Y. Rychkov
- Discipline of Physiology, School of Molecular and Biomedical Sciences, The University of Adelaide, Adelaide, South Australia, AUSTRALIA 5000
| | - L. Ashley Blackshaw
- Nerve-Gut Research Laboratory, Department of Gastroenterology & Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA 5000, Discipline of Physiology, School of Molecular and Biomedical Sciences, The University of Adelaide, Adelaide, South Australia, AUSTRALIA 5000, Discipline of Medicine, The University of Adelaide, Adelaide, South Australia, AUSTRALIA 5000
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