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Fukazawa A, Hori A, Hotta N, Katanosaka K, Estrada JA, Ishizawa R, Kim HK, Iwamoto GA, Smith SA, Vongpatanasin W, Mizuno M. Antagonism of TRPV4 channels partially reduces mechanotransduction in rat skeletal muscle afferents. J Physiol 2023; 601:1407-1424. [PMID: 36869605 PMCID: PMC10106437 DOI: 10.1113/jp284026] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 03/02/2023] [Indexed: 03/05/2023] Open
Abstract
Mechanical distortion of working skeletal muscle induces sympathoexcitation via thin fibre afferents, a reflex response known as the skeletal muscle mechanoreflex. However, to date, the receptor ion channels responsible for mechanotransduction in skeletal muscle remain largely undetermined. Transient receptor potential vanilloid 4 (TRPV4) is known to sense mechanical stimuli such as shear stress or osmotic pressure in various organs. It is hypothesized that TRPV4 in thin-fibre primary afferents innervating skeletal muscle is involved in mechanotransduction. Fluorescence immunostaining revealed that 20.1 ± 10.1% of TRPV4 positive neurons were small dorsal root ganglion (DRG) neurons that were DiI-labelled, and among them 9.5 ± 6.1% of TRPV4 co-localized with the C-fibre marker peripherin. In vitro whole-cell patch clamp recordings from cultured rat DRG neurons demonstrated that mechanically activated current amplitude was significantly attenuated after the application of the TRPV4 antagonist HC067047 compared to control (P = 0.004). Such reductions were also observed in single-fibre recordings from a muscle-nerve ex vivo preparation where HC067047 significantly decreased afferent discharge to mechanical stimulation (P = 0.007). Likewise, in an in vivo decerebrate rat preparation, the renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) responses to passive stretch of hindlimb muscle were significantly reduced by intra-arterial injection of HC067047 (ΔRSNA: P = 0.019, ΔMAP: P = 0.002). The findings suggest that TRPV4 plays an important role in mechanotransduction contributing to the cardiovascular responses evoked by the skeletal muscle mechanoreflex during exercise. KEY POINTS: Although a mechanical stimulus to skeletal muscle reflexively activates the sympathetic nervous system, the receptors responsible for mechanotransduction in skeletal muscle thin fibre afferents have not been fully identified. Evidence suggests that TRPV4 is a mechanosensitive channel that plays an important role in mechanotransduction within various organs. Immunocytochemical staining demonstrates that TRPV4 is expressed in group IV skeletal muscle afferents. In addition, we show that the TRPV4 antagonist HC067047 decreases the responsiveness of thin fibre afferents to mechanical stimulation at the muscle tissue level as well as at the level of dorsal root ganglion neurons. Moreover, we demonstrate that intra-arterial HC067047 injection attenuates the sympathetic and pressor responses to passive muscle stretch in decerebrate rats. These data suggest that antagonism of TRPV4 attenuates mechanotransduction in skeletal muscle afferents. The present study demonstrates a probable physiological role for TRPV4 in the regulation of mechanical sensation in somatosensory thin fibre muscle afferents.
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Affiliation(s)
- Ayumi Fukazawa
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Amane Hori
- Graduate School of Life and Health Sciences, Chubu University, Kasugai 487-850, Japan
- Japan Society for the Promotion of Science, Tokyo 102-8472, Japan
| | - Norio Hotta
- Graduate School of Life and Health Sciences, Chubu University, Kasugai 487-850, Japan
- College of Life and Health Sciences, Chubu University, Kasugai 487-850, Japan
| | - Kimiaki Katanosaka
- Graduate School of Life and Health Sciences, Chubu University, Kasugai 487-850, Japan
- College of Life and Health Sciences, Chubu University, Kasugai 487-850, Japan
| | - Juan A. Estrada
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Rie Ishizawa
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Han-Kyul Kim
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Gary A. Iwamoto
- Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Scott A. Smith
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Wanpen Vongpatanasin
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Masaki Mizuno
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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Benítez-Angeles M, Juárez-González E, Vergara-Jaque A, Llorente I, Rangel-Yescas G, Thébault SC, Hiriart M, Islas LD, Rosenbaum T. Unconventional interactions of the TRPV4 ion channel with beta-adrenergic receptor ligands. Life Sci Alliance 2023; 6:6/3/e202201704. [PMID: 36549871 PMCID: PMC9780703 DOI: 10.26508/lsa.202201704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 12/05/2022] [Accepted: 12/08/2022] [Indexed: 12/24/2022] Open
Abstract
The transient receptor potential vanilloid 4 (TRPV4) ion channel is present in different tissues including those of the airways. This channel is activated in response to stimuli such as changes in temperature, hypoosmotic conditions, mechanical stress, and chemicals from plants, lipids, and others. TRPV4's overactivity and/or dysfunction has been associated with several diseases, such as skeletal dysplasias, neuromuscular disorders, and lung pathologies such as asthma and cardiogenic lung edema and COVID-19-related respiratory malfunction. TRPV4 antagonists and blockers have been described; nonetheless, the mechanisms involved in achieving inhibition of the channel remain scarce, and the search for safe use of these molecules in humans continues. Here, we show that the widely used bronchodilator salbutamol and other ligands of β-adrenergic receptors inhibit TRPV4's activation. We also demonstrate that inhibition of TRPV4 by salbutamol is achieved through interaction with two residues located in the outer region of the pore and that salbutamol leads to channel closing, consistent with an allosteric mechanism. Our study provides molecular insights into the mechanisms that regulate the activity of this physiopathologically important ion channel.
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Affiliation(s)
- Miguel Benítez-Angeles
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México (UNAM), México, México
| | - Emmanuel Juárez-González
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México (UNAM), México, México
| | - Ariela Vergara-Jaque
- Center for Bioinformatics, Simulation and Modeling, Faculty of Engineering, Universidad de Talca, Talca, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases, Santiago, Chile
| | - Itzel Llorente
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México (UNAM), México, México
| | | | | | - Marcia Hiriart
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México (UNAM), México, México
| | - León D Islas
- Departamento de Fisiología, Facultad de Medicina, UNAM, México, México
| | - Tamara Rosenbaum
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México (UNAM), México, México
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Zhang M, Sykes DL, Brindle K, Sadofsky LR, Morice AH. Chronic cough-the limitation and advances in assessment techniques. J Thorac Dis 2022; 14:5097-5119. [PMID: 36647459 PMCID: PMC9840016 DOI: 10.21037/jtd-22-874] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 11/04/2022] [Indexed: 11/23/2022]
Abstract
Accurate and consistent assessments of cough are essential to advance the understanding of the mechanisms of cough and individualised the management of patients. Considerable progress has been made in this work. Here we reviewed the currently available tools for subjectively and objectively measuring both cough sensitivity and severity. We also provided some opinions on the new techniques and future directions. The simple and practical Visual Analogue Scale (VAS), the Leicester Cough Questionnaire (LCQ), and the Cough Specific Quality of Life Questionnaire (CQLQ) are the most widely used self-reported questionnaires for evaluating and quantifying cough severity. The Hull Airway Reflux Questionnaire (HARQ) is a tool to elucidate the constellation of symptoms underlying the diagnosis of chronic cough. Chemical excitation tests are widely used to explore the pathophysiological mechanisms of the cough reflex, such as capsaicin, citric acid and adenosine triphosphate (ATP) challenge test. Cough frequency is an ideal primary endpoint for clinical research, but the application of cough counters has been limited in clinical practice by the high cost and reliance on aural validation. The ongoing development of cough detection technology for smartphone apps and wearable devices will hopefully simplify cough counting, thus transitioning it from niche research to a widely available clinical application.
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Affiliation(s)
- Mengru Zhang
- Centre for Clinical Science, Respiratory Medicine, Hull York Medical School, University of Hull, Castle Hill Hospital, Cottingham, East Yorkshire, UK;,Department of Pulmonary and Critical Care Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Dominic L. Sykes
- Centre for Clinical Science, Respiratory Medicine, Hull York Medical School, University of Hull, Castle Hill Hospital, Cottingham, East Yorkshire, UK
| | - Kayleigh Brindle
- Centre for Clinical Science, Respiratory Medicine, Hull York Medical School, University of Hull, Castle Hill Hospital, Cottingham, East Yorkshire, UK
| | - Laura R. Sadofsky
- Centre for Clinical Science, Respiratory Medicine, Hull York Medical School, University of Hull, Castle Hill Hospital, Cottingham, East Yorkshire, UK
| | - Alyn H. Morice
- Centre for Clinical Science, Respiratory Medicine, Hull York Medical School, University of Hull, Castle Hill Hospital, Cottingham, East Yorkshire, UK
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Toumpanakis D, Chatzianastasiou A, Vassilakopoulou V, Mizi E, Dettoraki M, Perlikos F, Giatra G, Mikos N, Theocharis S, Vassilakopoulos T. TRPV4 Inhibition Exerts Protective Effects Against Resistive Breathing Induced Lung Injury. Int J Chron Obstruct Pulmon Dis 2022; 17:343-353. [PMID: 35210764 PMCID: PMC8857953 DOI: 10.2147/copd.s336108] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 02/03/2022] [Indexed: 11/23/2022] Open
Abstract
Introduction TRPV4 channels are calcium channels, activated by mechanical stress, that have been implicated in the pathogenesis of pulmonary inflammation. During resistive breathing (RB), increased mechanical stress is imposed on the lung, inducing lung injury. The role of TRPV4 channels in RB-induced lung injury is unknown. Materials and Methods Spontaneously breathing adult male C57BL/6 mice were subjected to RB by tracheal banding. Following anaesthesia, mice were placed under a surgical microscope, the surface area of the trachea was measured and a nylon band was sutured around the trachea to reduce area to half. The specific TRPV4 inhibitor, HC-067047 (10 mg/kg ip), was administered either prior to RB and at 12 hrs following initiation of RB (preventive) or only at 12 hrs after the initiation of RB (therapeutic protocol). Lung injury was assessed at 24 hrs of RB, by measuring lung mechanics, total protein, BAL total and differential cell count, KC and IL-6 levels in BAL fluid, surfactant Protein (Sp)D in plasma and a lung injury score by histology. Results RB decreased static compliance (Cst), increased total protein in BAL (p < 0.001), total cell count due to increased number of both macrophages and neutrophils, increased KC and IL-6 in BAL (p < 0.001 and p = 0.01, respectively) and plasma SpD (p < 0.0001). Increased lung injury score was detected. Both preventive and therapeutic HC-067047 administration restored Cst and inhibited the increase in total protein, KC and IL-6 levels in BAL fluid, compared to RB. Preventive TRPV4 inhibition ameliorated the increase in BAL cellularity, while therapeutic TRPV4 inhibition exerted a partial effect. TRPV4 inhibition blunted the increase in plasma SpD (p < 0.001) after RB and the increase in lung injury score was also inhibited. Conclusion TRPV4 inhibition exerts protective effects against RB-induced lung injury.
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Affiliation(s)
- Dimitrios Toumpanakis
- “Marianthi Simou” Applied Biomedical Research and Training Center, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
- Correspondence: Dimitrios Toumpanakis, Email
| | - Athanasia Chatzianastasiou
- “Marianthi Simou” Applied Biomedical Research and Training Center, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Vyronia Vassilakopoulou
- “Marianthi Simou” Applied Biomedical Research and Training Center, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Eleftheria Mizi
- “Marianthi Simou” Applied Biomedical Research and Training Center, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Maria Dettoraki
- “Marianthi Simou” Applied Biomedical Research and Training Center, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Fotis Perlikos
- “Marianthi Simou” Applied Biomedical Research and Training Center, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Georgia Giatra
- “Marianthi Simou” Applied Biomedical Research and Training Center, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
- 3 Department of Critical Care Medicine, Evgenideio Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Nikolaos Mikos
- Allergology Department, Laiko General Hospital, Athens, Greece
| | - Stamatios Theocharis
- First Department of Pathology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Theodoros Vassilakopoulos
- “Marianthi Simou” Applied Biomedical Research and Training Center, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
- 3 Department of Critical Care Medicine, Evgenideio Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
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Gu Q, Lee LY. TRP channels in airway sensory nerves. Neurosci Lett 2021; 748:135719. [PMID: 33587987 PMCID: PMC7988689 DOI: 10.1016/j.neulet.2021.135719] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 02/01/2021] [Accepted: 02/03/2021] [Indexed: 12/12/2022]
Abstract
Transient Receptor Potential (TRP) channels expressed in specific subsets of airway sensory nerves function as transducers and integrators of a diverse range of sensory inputs including chemical, mechanical and thermal signals. These TRP sensors can detect inhaled irritants as well as endogenously released chemical substances. They play an important role in generating the afferent activity carried by these sensory nerves and regulating the centrally mediated pulmonary defense reflexes. Increasing evidence reported in recent investigations has revealed important involvements of several TRP channels (TRPA1, TRPV1, TRPV4 and TRPM8) in the manifestation of various symptoms and pathogenesis of certain acute and chronic airway diseases. This mini-review focuses primarily on these recent findings of the responses of these TRP sensors to the biological stresses emerging under the pathophysiological conditions of the lung and airways.
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Affiliation(s)
- Qihai Gu
- Department of Biomedical Sciences, Mercer University School of Medicine, 1501 Mercer University Drive, Macon, GA, 31207, USA.
| | - Lu-Yuan Lee
- Department of Physiology, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY, 40536-0298, USA.
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Redmon SN, Yarishkin O, Lakk M, Jo A, Mustafić E, Tvrdik P, Križaj D. TRPV4 channels mediate the mechanoresponse in retinal microglia. Glia 2021; 69:1563-1582. [PMID: 33624376 PMCID: PMC8989051 DOI: 10.1002/glia.23979] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 02/02/2021] [Accepted: 02/02/2021] [Indexed: 12/12/2022]
Abstract
The physiological and neurological correlates of plummeting brain osmolality during edema, traumatic CNS injury, and severe ischemia are compounded by neuroinflammation. Using multiple approaches, we investigated how retinal microglia respond to challenges mediated by increases in strain, osmotic gradients, and agonists of the stretch-activated cation channel TRPV4. Dissociated and intact microglia were TRPV4-immunoreactive and responded to the selective agonist GSK1016790A and substrate stretch with altered motility and elevations in intracellular calcium ([Ca2+ ]i ). Agonist- and hypotonicity-induced swelling was associated with a nonselective outwardly rectifying cation current, increased [Ca2+ ]i , and retraction of higher-order processes. The antagonist HC067047 reduced the extent of hypotonicity-induced microglial swelling and inhibited the suppressive effects of GSK1016790A and hypotonicity on microglial branching. Microglial TRPV4 signaling required intermediary activation of phospholipase A2 (PLA2), cytochrome P450, and epoxyeicosatrienoic acid production (EETs). The expression pattern of vanilloid thermoTrp genes in retinal microglia was markedly different from retinal neurons, astrocytes, and cortical microglia. These results suggest that TRPV4 represents a primary retinal microglial sensor of osmochallenges under physiological and pathological conditions. Its activation, associated with PLA2, modulates calcium signaling and cell architecture. TRPV4 inhibition might be a useful strategy to suppress microglial overactivation in the swollen and edematous CNS.
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Affiliation(s)
- Sarah N Redmon
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, Utah, USA
| | - Oleg Yarishkin
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, Utah, USA
| | - Monika Lakk
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, Utah, USA
| | - Andrew Jo
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, Utah, USA
| | - Edin Mustafić
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, Utah, USA
| | - Petr Tvrdik
- Department of Neurological Surgery, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - David Križaj
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, Utah, USA.,Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah, USA.,Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA.,Department of Neurobiology & Anatomy, University of Utah, Salt Lake City, Utah, USA
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Jentsch Matias de Oliveira JR, Amorim MA, André E. The role of TRPA1 and TRPV4 channels in bronchoconstriction and plasma extravasation in airways of rats treated with captopril. Pulm Pharmacol Ther 2021; 65:102004. [PMID: 33610768 DOI: 10.1016/j.pupt.2021.102004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 02/05/2021] [Accepted: 02/13/2021] [Indexed: 12/16/2022]
Abstract
Angiotensin-converting enzyme inhibitors (ACEis) may cause adverse airway events, such as cough and angioedema, due to a reduction in bradykinin breakdown and consequent activation of bradykinin type 2 receptor (B2 receptor). Recent studies have shown that bradykinin can also sensitize pro-inflammatory receptors such as the transient receptor potential ankyrin 1 (TRPA1) and vanilloid 4 (TRPV4), which are implicated in several inflammatory airway diseases. Based on these considerations, the aim of this study was to understand the role of TRPA1 and TRPV4 channels in the bronchoconstrictive response and plasma extravasation in the trachea of rats pretreated with captopril. Using methods to detect alterations in airway resistance and plasma extravasation, we found that intravenous (i.v.) administration of bradykinin (0.03-0.3 μmol/kg, B2 receptor agonist), allyl isothiocyanate (100-1000 μmol/kg, TRPA1 agonist) or GSK1016790A (0.01-0.1 μmol/kg, TRPV4 agonist), but not des-arg9-bradykinin (DABK; 100-300 μmol/kg, B1 receptor agonist), induced bronchoconstriction in anaesthetized rats. In doses that did not cause significant bronchoconstriction, bradykinin (0.03 μmol/kg) or allyl isothiocyanate (100 μmol/kg), but not GSK1016790A (0.01 μmol/kg) or DABK (300 μmol/kg) induced an increased bronchoconstrictive response in rats pretreated with captopril (2.5 mg/kg, i.v.). On the other hand, in rats pretreated with captopril (5 mg/kg, i.v.), an increased bronchoconstrictive response to GSK1016790A (0.01 μmol/kg) was observed. The bronchoconstrictive response induced by bradykinin in captopril-pretreated rats was inhibited by intratracheal treatment (i.t.) with HC030031 (300 μg/50 μl; 36 ± 9%) or HC067047 (300 μg/50 μl; 35.1 ± 16%), for TRPA1 and TRPV4 antagonists, respectively. However, the co-administration of both antagonists did not increase this inhibition. The bronchoconstriction induced by allyl isothiocyanate in captopril-pretreated rats (2.5 mg/kg) was inhibited (58.3 ± 8%) by the B2 receptor antagonist HOE140 (10 nmol/50 μl, i.t.). Similarly, the bronchoconstriction induced by GSK1016790A in captopril-pretreated rats (5 mg/kg) was also inhibited (84.2 ± 4%) by HOE140 (10 nmol/50 μl, i.t.). Furthermore, the plasma extravasation induced by captopril on the trachea of rats was inhibited by pretreatment with HC030031 (47.2 ± 8%) or HC067047 (38.9 ± 8%). Collectively, these findings support the hypothesis that TRPA1 and TRPV4, via a B2 receptor activation-dependent pathway, are involved in the plasma extravasation and bronchoconstriction induced by captopril, making them possible pharmacological targets to prevent or remediate ACEi-induced adverse respiratory reactions.
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Affiliation(s)
| | | | - Eunice André
- Department of Pharmacology, Federal University of Paraná, Curitiba, Brazil.
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8
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Lapajne L, Lakk M, Yarishkin O, Gubeljak L, Hawlina M, Križaj D. Polymodal Sensory Transduction in Mouse Corneal Epithelial Cells. Invest Ophthalmol Vis Sci 2020; 61:2. [PMID: 32271891 PMCID: PMC7401707 DOI: 10.1167/iovs.61.4.2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Purpose Contact lenses, osmotic stressors, and chemical burns may trigger severe discomfort and vision loss by damaging the cornea, but the signaling mechanisms used by corneal epithelial cells (CECs) to sense extrinsic stressors are not well understood. We therefore investigated the mechanisms of swelling, temperature, strain, and chemical transduction in mouse CECs. Methods Intracellular calcium imaging in conjunction with electrophysiology, pharmacology, transcript analysis, immunohistochemistry, and bioluminescence assays of adenosine triphosphate (ATP) release were used to track mechanotransduction in dissociated CECs and epithelial sheets isolated from the mouse cornea. Results The transient receptor potential vanilloid (TRPV) transcriptome in the mouse corneal epithelium is dominated by Trpv4, followed by Trpv2, Trpv3, and low levels of Trpv1 mRNAs. TRPV4 protein was localized to basal and intermediate epithelial strata, keratocytes, and the endothelium in contrast to the cognate TRPV1, which was confined to intraepithelial afferents and a sparse subset of CECs. The TRPV4 agonist GSK1016790A induced cation influx and calcium elevations, which were abolished by the selective blocker HC067047. Hypotonic solutions, membrane strain, and moderate heat elevated [Ca2+]CEC with swelling- and temperature-, but not strain-evoked signals, sensitive to HC067047. GSK1016790A and swelling evoked calcium-dependent ATP release, which was suppressed by HC067027 and the hemichannel blocker probenecid. Conclusions These results demonstrate that cation influx via TRPV4 transduces osmotic and thermal but not strain inputs to CECs and promotes hemichannel-dependent ATP release. The TRPV4-hemichannel-ATP signaling axis might modulate corneal pain induced by excessive mechanical, osmotic, and chemical stimulation.
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Rosenbaum T, Benítez-Angeles M, Sánchez-Hernández R, Morales-Lázaro SL, Hiriart M, Morales-Buenrostro LE, Torres-Quiroz F. TRPV4: A Physio and Pathophysiologically Significant Ion Channel. Int J Mol Sci 2020; 21:ijms21113837. [PMID: 32481620 PMCID: PMC7312103 DOI: 10.3390/ijms21113837] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 05/23/2020] [Accepted: 05/24/2020] [Indexed: 02/07/2023] Open
Abstract
Transient Receptor Potential (TRP) channels are a family of ion channels whose members are distributed among all kinds of animals, from invertebrates to vertebrates. The importance of these molecules is exemplified by the variety of physiological roles they play. Perhaps, the most extensively studied member of this family is the TRPV1 ion channel; nonetheless, the activity of TRPV4 has been associated to several physio and pathophysiological processes, and its dysfunction can lead to severe consequences. Several lines of evidence derived from animal models and even clinical trials in humans highlight TRPV4 as a therapeutic target and as a protein that will receive even more attention in the near future, as will be reviewed here.
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Affiliation(s)
- Tamara Rosenbaum
- Departamento de Neurociencia Cognitiva, División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (M.B.-A.); (R.S.-H.); (S.L.M.-L.); (M.H.)
- Correspondence: ; Tel.: +52-555-622-56-24; Fax: +52-555-622-56-07
| | - Miguel Benítez-Angeles
- Departamento de Neurociencia Cognitiva, División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (M.B.-A.); (R.S.-H.); (S.L.M.-L.); (M.H.)
| | - Raúl Sánchez-Hernández
- Departamento de Neurociencia Cognitiva, División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (M.B.-A.); (R.S.-H.); (S.L.M.-L.); (M.H.)
| | - Sara Luz Morales-Lázaro
- Departamento de Neurociencia Cognitiva, División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (M.B.-A.); (R.S.-H.); (S.L.M.-L.); (M.H.)
| | - Marcia Hiriart
- Departamento de Neurociencia Cognitiva, División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (M.B.-A.); (R.S.-H.); (S.L.M.-L.); (M.H.)
| | - Luis Eduardo Morales-Buenrostro
- Departamento de Nefrología y Metabolismo Mineral, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City 14080, Mexico;
| | - Francisco Torres-Quiroz
- Departamento de Bioquímica y Biología Estructural, División Investigación Básica, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico;
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10
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Zhang M, Wang S, Yu L, Xu X, Qiu Z. The role of ATP in cough hypersensitivity syndrome: new targets for treatment. J Thorac Dis 2020; 12:2781-2790. [PMID: 32642186 PMCID: PMC7330343 DOI: 10.21037/jtd-20-cough-001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Clinically, chronic cough can be effectively controlled in most patients by etiological treatment; however, there remain a small number of patients whose cough has unidentifiable etiology or where treatment efficacy is poor following etiology identification, whose condition is described as unexplained chronic cough or refractory chronic cough. Patients with refractory chronic or unexplained chronic cough commonly have increased cough reflex sensitivity, which has been described as cough hypersensitivity syndrome. The adenosine triphosphate (ATP)-gated P2X3 receptor may be a key link in the activation of sensory neurons that regulate cough reflexes and has recently draw attention as a potential target for the treatment of refractory chronic cough, with a number of clinical studies validating the therapeutic effects of P2X3 receptor antagonists in patients with this condition. As the energy source for various cells in vivo, ATP localizes within cells under normal physiological conditions, and has physiological functions, including in metabolism; however, under some pathological circumstances, ATP can act as a neuromodulator and is released into the extracellular space in large quantities as a signal transduction molecule. In addition, ATP is involved in regulation of airway inflammation and the cough reflex. Here, we review the generation, release, and regulation of ATP during airway inflammation and its role in the etiology of cough hypersensitivity syndrome, including the potential underlying mechanism.
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Affiliation(s)
- Mengru Zhang
- Department of Pulmonary and Critical Care Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, China
| | - Shengyuan Wang
- Department of Pulmonary and Critical Care Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, China
| | - Li Yu
- Department of Pulmonary and Critical Care Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, China
| | - Xianghuai Xu
- Department of Pulmonary and Critical Care Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, China
| | - Zhongmin Qiu
- Department of Pulmonary and Critical Care Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, China
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11
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Wei W, Gao X, Zhao L, Zhuang J, Jiao Y, Xu F. Liquiritin apioside attenuates laryngeal chemoreflex but not mechanoreflex in rat pups. Am J Physiol Lung Cell Mol Physiol 2020; 318:L89-L97. [PMID: 31617735 PMCID: PMC6985871 DOI: 10.1152/ajplung.00306.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 10/10/2019] [Accepted: 10/10/2019] [Indexed: 02/08/2023] Open
Abstract
Liquiritin apioside (LA), a main flavonoid component of licorice, reportedly suppresses cough responses to inhalation of aerosolized capsaicin [CAP; a stimulant to transient receptor potential vanilloid 1 (TRPV1)] in conscious guinea pigs via acting on peripheral nerves. However, the evidence of LA having a direct effect on airway sensory fibers is lacking. Considering the important role laryngeal chemoreceptors and mechanoreceptors play in triggering apnea and cough, we studied whether LA suppressed the apneic responses to stimulation of these receptors via directly acting on the superior laryngeal nerve (SLN). Intralaryngeal delivery of chemical [CAP, HCl, and distilled water (DW)] and mechanical [an air-pulse (AP)] stimulations was applied in anesthetized rat pups to evoke the apnea. These stimuli were repeated after intralaryngeal LA treatment or peri-SLN LA treatment to determine the direct effect of LA on the SLN. Our results showed that all stimuli triggered an immediate apnea. Intralaryngeal LA treatment significantly attenuated the apneic response to chemical but not mechanical stimulations. The same attenuation was observed after peri-SLN LA treatment. Owing that TRPV1 receptors of laryngeal C fibers are responsible for the CAP-triggered apneas, the LA impact on the activity of laryngeal C neurons retrogradely traced by DiI was subsequently studied using a patch-clamp approach. LA pretreatment significantly altered the electrophysiological kinetics of CAP-induced currents in laryngeal C neurons by reducing their amplitudes, increasing the rise times, and prolonging the decay times. In conclusion, our results, for the first time, reveal that LA suppresses the laryngeal chemoreceptor-mediated apnea by directly acting on the SLN (TRPV1 receptors of laryngeal C fibers).
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Affiliation(s)
- Wan Wei
- Pathophysiology Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
- Graduate School, Beijing University of Chinese Medicine, Beijing, China
| | - Xiuping Gao
- Pathophysiology Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Lei Zhao
- Pathophysiology Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Jianguo Zhuang
- Pathophysiology Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Yang Jiao
- Dongfang Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, China
| | - Fadi Xu
- Pathophysiology Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
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12
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Zhao L, Gao X, Zhuang J, Wallen M, Leng S, Xu F. Prolongation of bronchopulmonary C-fiber-mediated apnea by prenatal nicotinic exposure in rat pups: role of 5-HT 3 receptors. FASEB J 2019; 33:10731-10741. [PMID: 31251077 PMCID: PMC6766661 DOI: 10.1096/fj.201900279rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 06/04/2019] [Indexed: 01/30/2023]
Abstract
Prenatal nicotinic exposure (PNE) reportedly sensitizes bronchopulmonary C-fibers (PCFs) and prolongs PCF-mediated apnea in rat pups, contributing to the pathogenesis of sudden infant death syndrome. Serotonin, or 5-hydroxytryptamine (5-HT), induces apnea via acting on 5-HT receptor 3 (5-HT3R) in PCFs, and among the 5-HT3R subunits, 5-HT3B is responsible for shortening the decay time of 5-HT3R-mediated currents. We examined whether PNE would promote pulmonary 5-HT secretion and prolong the apnea mediated by 5-HT3Rs in PCFs via affecting the 5-HT3B subunit. To this end, the following variables were compared between the control and PNE rat pups: 1) the 5-HT content in bronchoalveolar lavage fluid, 2) the apneic response to the right atrial bolus injection of phenylbiguanide (a 5-HT3R agonist) before and after PCF inactivation, 3) 5-HT3R currents and the stimulus threshold of the action currents of vagal pulmonary C-neurons, and 4) the immunoreactivity (IR) and mRNA expression of 5-HT3A and 5-HT3B in these neurons. Our results showed that PNE up-regulated the pulmonary 5-HT concentration and strengthened the PCF 5-HT3R-mediated apnea. PNE significantly facilitated neural excitability by shortening the decay time of 5-HT3R currents, lowering the stimulus threshold, and increasing 5-HT3B IR. In summary, PNE prolongs the apnea mediated by 5-HT3Rs in PCFs, likely by increasing 5-HT3B subunits to enhance the excitability of 5-HT3 channels.-Zhao, L., Gao, X., Zhuang, J., Wallen, M., Leng, S., Xu, F. Prolongation of bronchopulmonary C-fiber-mediated apnea by prenatal nicotinic exposure in rat pups: role of 5-HT3 receptors.
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MESH Headings
- Animals
- Animals, Newborn
- Apnea/etiology
- Apnea/genetics
- Apnea/physiopathology
- Biguanides/administration & dosage
- Bronchoalveolar Lavage Fluid/chemistry
- Disease Models, Animal
- Female
- Humans
- Infant, Newborn
- Lung/drug effects
- Lung/innervation
- Lung/physiopathology
- Male
- Nerve Fibers, Unmyelinated/drug effects
- Nerve Fibers, Unmyelinated/physiology
- Nicotine/administration & dosage
- Nicotine/toxicity
- Pregnancy
- Prenatal Exposure Delayed Effects/etiology
- Prenatal Exposure Delayed Effects/physiopathology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Serotonin, 5-HT3/genetics
- Receptors, Serotonin, 5-HT3/physiology
- Serotonin/metabolism
- Serotonin 5-HT3 Receptor Agonists/administration & dosage
- Sudden Infant Death/etiology
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Affiliation(s)
- Lei Zhao
- Pathophysiological Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Xiuping Gao
- Pathophysiological Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Jianguo Zhuang
- Pathophysiological Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Morgan Wallen
- Department of Arts and Sciences, University of Tennessee, Knoxville, Tennessee, USA
| | - Shuguang Leng
- Pathophysiological Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Fadi Xu
- Pathophysiological Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
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13
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Lakk M, Young D, Baumann JM, Jo AO, Hu H, Križaj D. Polymodal TRPV1 and TRPV4 Sensors Colocalize but Do Not Functionally Interact in a Subpopulation of Mouse Retinal Ganglion Cells. Front Cell Neurosci 2018; 12:353. [PMID: 30386208 PMCID: PMC6198093 DOI: 10.3389/fncel.2018.00353] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 09/20/2018] [Indexed: 01/23/2023] Open
Abstract
Retinal ganglion cells (RGCs) are projection neurons that transmit the visual signal from the retina to the brain. Their excitability and survival can be strongly influenced by mechanical stressors, temperature, lipid metabolites, and inflammatory mediators but the transduction mechanisms for these non-synaptic sensory inputs are not well characterized. Here, we investigate the distribution, functional expression, and localization of two polymodal transducers of mechanical, lipid, and inflammatory signals, TRPV1 and TRPV4 cation channels, in mouse RGCs. The most abundant vanilloid mRNA species was Trpv4, followed by Trpv2 and residual expression of Trpv3 and Trpv1. Immunohistochemical and functional analyses showed that TRPV1 and TRPV4 channels are expressed as separate molecular entities, with TRPV1-only (∼10%), TRPV4-only (∼40%), and TRPV1 + TRPV4 (∼10%) expressing RGC subpopulations. The TRPV1 + TRPV4 cohort included SMI-32-immunopositive alpha RGCs, suggesting potential roles for polymodal signal transduction in modulation of fast visual signaling. Arguing against obligatory heteromerization, optical imaging showed that activation and desensitization of TRPV1 and TRPV4 responses evoked by capsaicin and GSK1016790A are independent of each other. Overall, these data predict that RGC subpopulations will be differentially sensitive to mechanical and inflammatory stressors.
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Affiliation(s)
- Monika Lakk
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, United States
| | - Derek Young
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, United States
| | - Jackson M Baumann
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, United States.,Department of Bioengineering, University of Utah, Salt Lake City, UT, United States
| | - Andrew O Jo
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, United States
| | - Hongzhen Hu
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
| | - David Križaj
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, United States.,Department of Bioengineering, University of Utah, Salt Lake City, UT, United States.,Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT, United States
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14
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Matsumoto K, Yamaba R, Inoue K, Utsumi D, Tsukahara T, Amagase K, Tominaga M, Kato S. Transient receptor potential vanilloid 4 channel regulates vascular endothelial permeability during colonic inflammation in dextran sulphate sodium-induced murine colitis. Br J Pharmacol 2017; 175:84-99. [PMID: 29053877 DOI: 10.1111/bph.14072] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 09/14/2017] [Accepted: 10/08/2017] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND AND PURPOSE The transient receptor potential vanilloid 4 (TRPV4) channel is a non-selective cation channel involved in physical sensing in various tissue types. The present study aimed to elucidate the function and expression of TRPV4 channels in colonic vascular endothelial cells during dextran sulphate sodium (DSS)-induced colitis. EXPERIMENTAL APPROACH The role of TRPV4 channels in the progression of colonic inflammation was examined in a murine DSS-induced colitis model using immunohistochemical analysis, Western blotting and Evans blue dye extrusion assay. KEY RESULTS DSS-induced colitis was significantly attenuated in TRPV4-deficient (TRPV4 KO) as compared to wild-type mice. Repeated intrarectal administration of GSK1016790A, a TRPV4 agonist, exacerbated the severity of DSS-induced colitis. Bone marrow transfer experiments demonstrated the important role of TRPV4 in non-haematopoietic cells for DSS-induced colitis. DSS treatment up-regulated TRPV4 expression in the vascular endothelia of colonic mucosa and submucosa. DSS treatment increased vascular permeability, which was abolished in TRPV4 KO mice. This DSS-induced increase in vascular permeability was further enhanced by i.v. administration of GSK1016790A, and this effect was abolished by the TRPV4 antagonist RN1734. TRPV4 was co-localized with vascular endothelial (VE)-cadherin, and VE-cadherin expression was decreased by repeated i.v. administration of GSK1016790A during colitis. Furthermore, GSK106790A decreased VE-cadherin expression in mouse aortic endothelial cells exposed to TNF-α. CONCLUSION AND IMPLICATIONS These findings indicate that an up-regulation of TRPV4 channels in vascular endothelial cells contributes to the progression of colonic inflammation by increasing vascular permeability. Thus, TRPV4 is an attractive target for the treatment of inflammatory bowel diseases.
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Affiliation(s)
- Kenjiro Matsumoto
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Riho Yamaba
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Ken Inoue
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Daichi Utsumi
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Takuya Tsukahara
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Kikuko Amagase
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Makoto Tominaga
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), Okazaki, Japan
| | - Shinichi Kato
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto, Japan
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15
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Gao X, Zhao L, Zhuang J, Zang N, Xu F. Prenatal nicotinic exposure prolongs superior laryngeal C-fiber-mediated apnea and bradycardia through enhancing neuronal TRPV1 expression and excitation. FASEB J 2017; 31:4325-4334. [PMID: 28615326 PMCID: PMC5602895 DOI: 10.1096/fj.201700163r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 05/30/2017] [Indexed: 02/03/2023]
Abstract
Maternal cigarette smoke, including prenatal nicotinic exposure (PNE), is responsible for sudden infant death syndrome (SIDS). The fatal events of SIDS are characterized by severe bradycardia and life-threatening apneas. Although activation of transient receptor potential vanilloid 1 (TRPV1) of superior laryngeal C fibers (SLCFs) could induce bradycardia and apnea and has been implicated in SIDS pathogenesis, how PNE affects the SLCF-mediated cardiorespiratory responses remains unexplored. Here, we tested the hypothesis that PNE would aggravate the SLCF-mediated apnea and bradycardia via up-regulating TRPV1 expression and excitation of laryngeal C neurons in the nodose/jugular (N/J) ganglia. To this end, we compared the following outcomes between control and PNE rat pups at postnatal days 11-14: 1) the cardiorespiratory responses to intralaryngeal application of capsaicin (10 µg/ml, 50 µl), a selective stimulant for TRPV1 receptors, in anesthetized preparation; 2) immunoreactivity and mRNA of TRPV1 receptors of laryngeal sensory C neurons in the N/J ganglia retrogradely traced by 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate; and 3) TRPV1 currents and electrophysiological characteristics of these neurons by using whole-cell patch-clamp technique in vitro Our results showed that PNE markedly prolonged the apneic response and exacerbated the bradycardic response to intralaryngeal perfusion of capsaicin, which was associated with up-regulation of TRPV1 expression in laryngeal C neurons. In addition, PNE increased the TRPV1 currents, depressed the slow delayed rectifier potassium currents, and increased the resting membrane potential of these neurons. Our results suggest that PNE is capable of aggravating the SLCF-mediated apnea and bradycardia through TRPV1 sensitization and neuronal excitation, which may contribute to the pathogenesis of SIDS.-Gao, X., Zhao, L., Zhuang, J., Zang, N., Xu, F. Prenatal nicotinic exposure prolongs superior laryngeal C-fiber-mediated apnea and bradycardia through enhancing neuronal TRPV1 expression and excitation.
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Affiliation(s)
- Xiuping Gao
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Lei Zhao
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Jianguo Zhuang
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Na Zang
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Fadi Xu
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
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16
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Gu QD, Joe DS, Gilbert CA. Activation of bitter taste receptors in pulmonary nociceptors sensitizes TRPV1 channels through the PLC and PKC signaling pathway. Am J Physiol Lung Cell Mol Physiol 2017; 312:L326-L333. [PMID: 28062485 DOI: 10.1152/ajplung.00468.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/03/2017] [Accepted: 01/03/2017] [Indexed: 11/22/2022] Open
Abstract
Bitter taste receptors (T2Rs), a G protein-coupled receptor family capable of detecting numerous bitter-tasting compounds, have recently been shown to be expressed and play diverse roles in many extraoral tissues. Here we report the functional expression of T2Rs in rat pulmonary sensory neurons. In anesthetized spontaneously breathing rats, intratracheal instillation of T2R agonist chloroquine (10 mM, 0.1 ml) significantly augmented chemoreflexes evoked by right-atrial injection of capsaicin, a specific activator for transient receptor potential vanilloid receptor 1 (TRPV1), whereas intravenous infusion of chloroquine failed to significantly affect capsaicin-evoked reflexes. In patch-clamp recordings with isolated rat vagal pulmonary sensory neurons, pretreatment with chloroquine (1-1,000 µM, 90 s) concentration dependently potentiated capsaicin-induced TRPV1-mediated inward currents. Preincubating with diphenitol and denatonium (1 mM, 90 s), two other T2R activators, also enhanced capsaicin currents in these neurons but to a lesser extent. The sensitizing effect of chloroquine was effectively prevented by the phospholipase C inhibitor U73122 (1 µM) or by the protein kinase C inhibitor chelerythrine (10 µM). In summary, our study showed that activation of T2Rs augments capsaicin-evoked TRPV1 responses in rat pulmonary nociceptors through the phospholipase C and protein kinase C signaling pathway.
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Affiliation(s)
- Qihai David Gu
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, Georgia
| | - Deanna S Joe
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, Georgia
| | - Carolyn A Gilbert
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, Georgia
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