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Zhi H, Zhong M, Huang J, Zheng Z, Ji X, Xu Y, Dong J, Yan W, Chen Z, Zhan C, Chen R. Gabapentin alleviated the cough hypersensitivity and neurogenic inflammation in a guinea pig model with repeated intra-esophageal acid perfusion. Eur J Pharmacol 2023; 959:176078. [PMID: 37805133 DOI: 10.1016/j.ejphar.2023.176078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 10/09/2023]
Abstract
OBJECTIVE The anti-tussive effect of gabapentin and its underlying neuromodulatory mechanism were investigated via a modified guinea pig model of gastroesophageal reflux-related cough (GERC). METHODS Intra-esophageal perfusion with hydrochloric acid (HCl) was performed every other day 12 times to establish the GERC model. High-dose gabapentin (48 mg/kg), low-dose gabapentin (8 mg/kg), or saline was orally administered for 2 weeks after modeling. Cough sensitivity, airway inflammation, lung and esophagus histology, levels of substance P (SP), and neurokinin-1 (NK1)-receptors were monitored. RESULTS Repeated intra-esophageal acid perfusion aggravated the cough sensitivity in guinea pigs in a time-dependent manner. The number of cough events was significantly increased after 12 times HCl perfusion, and the hypersensitivity period was maintained for 2 weeks. The SP levels in BALF, trachea, lung, distal esophagus, and vagal ganglia were increased in guinea pigs receiving HCl perfusion. The intensity of cough hypersensitivity in the GERC model was significantly correlated with increased SP expression in the airways. Both high and low doses of gabapentin administration could reduce cough hypersensitivity exposed to HCl perfusion, attenuate airway inflammatory damage, and inhibit neurogenic inflammation by reducing SP expression from the airway and vagal ganglia. CONCLUSIONS Gabapentin can desensitize the cough sensitivity in the GERC model of guinea pig. The anti-tussive effect is associated with the alleviated peripheral neurogenic inflammation as reflected in the decreased level of SP.
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Affiliation(s)
- Haopeng Zhi
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, Department of Allergy and Clinical Immunology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, Guangdong, China.
| | - Mingyu Zhong
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, Department of Allergy and Clinical Immunology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, Guangdong, China.
| | - Junfeng Huang
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, Department of Allergy and Clinical Immunology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, Guangdong, China.
| | - Ziwen Zheng
- Guangzhou Medical University, Guangzhou, Guangdong, 510180, China.
| | - Xiaolong Ji
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, Department of Allergy and Clinical Immunology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, Guangdong, China.
| | - Yilin Xu
- Guangzhou Medical University, Guangzhou, Guangdong, 510180, China.
| | - Junguo Dong
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, Department of Allergy and Clinical Immunology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, Guangdong, China.
| | - Wenbo Yan
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, Department of Allergy and Clinical Immunology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, Guangdong, China.
| | - Zhe Chen
- Laboratory of Cough, Affiliated Kunshan Hospital of Jiangsu University, Suzhou, Jiangsu, 215300, China.
| | - Chen Zhan
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, Department of Allergy and Clinical Immunology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, Guangdong, China.
| | - Ruchong Chen
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, Department of Allergy and Clinical Immunology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, Guangdong, China.
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Effect of centrally and peripherally acting GABA B agonism on the healthy human cough reflex. Pulm Pharmacol Ther 2021; 71:102079. [PMID: 34571095 DOI: 10.1016/j.pupt.2021.102079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/07/2021] [Accepted: 09/22/2021] [Indexed: 01/19/2023]
Abstract
BACKGROUND Currently there are no effective licensed anti-tussive therapies. Understanding how the neuronal mechanisms mediating the cough reflex in animal models translate to humans is important for the development of effective therapies. Pre-clinical studies suggest that the activation of GABAB receptors in both the peripheral and central nervous systems inhibit cough. OBJECTIVE To compare the effect of central and peripherally acting GABAB agonists (lesogaberan and baclofen) on the cough reflex in healthy volunteers. METHODS We performed a single center, double-blind, double-dummy, three-way crossover trial in healthy controls comparing single doses of lesogaberan (120 mg MR), with baclofen (40 mg) and placebos. Cough responses to inhaled capsaicin were assessed at screening and 2h post-dose on each study day. The primary endpoint was the maximum number of coughs evoked at any concentration of capsaicin (Emax) and the secondary endpoint was the concentration evoking 50% of the maximal response (ED50). RESULTS Fifteen participants enrolled onto the study (median age 29 (IQR 25-44) years; 7 females, mean BMI 24.6(±3.0). Lesogaberan treatment produced a small, statistically significant increase in Emax compared with placebo [mean 13.4coughs (95%CI 10.1-17.9) vs. 11.8coughs (8.8-15.9), p = 0.04], but had no effect on ED50 [geometric mean 47.4 μM (95%CI 24.4-91.7) vs 37.6 μM (95%CI 19.2-73.5), p = 0.37]. In contrast, baclofen had no significant effect on Emax (11.1, 95%CI 8.1-15.4) (p = 0.23), but significantly increased ED50 compared with placebo (geometric mean 75.2 μM (95%CI 37.2-151.8), p = 0.002). CONCLUSION This data suggests the anti-tussive actions of GABAB agonists, in healthy volunteers, occur in the central rather than the peripheral nervous system.
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Olsen WL, Rose M, Golder FJ, Wang C, Hammond JC, Bolser DC. Intra-Arterial, but Not Intrathecal, Baclofen and Codeine Attenuates Cough in the Cat. Front Physiol 2021; 12:640682. [PMID: 33746778 PMCID: PMC7973226 DOI: 10.3389/fphys.2021.640682] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 02/15/2021] [Indexed: 11/15/2022] Open
Abstract
Centrally-acting antitussive drugs are thought to act solely in the brainstem. However, the role of the spinal cord in the mechanism of action of these drugs is unknown. The purpose of this study was to determine if antitussive drugs act in the spinal cord to reduce the magnitude of tracheobronchial (TB) cough-related expiratory activity. Experiments were conducted in anesthetized, spontaneously breathing cats (n = 22). Electromyograms (EMG) were recorded from the parasternal (PS) and transversus abdominis (TA) or rectus abdominis muscles. Mechanical stimulation of the trachea or larynx was used to elicit TB cough. Baclofen (10 and 100 μg/kg, GABA-B receptor agonist) or codeine (30 μg/kg, opioid receptor agonist) was administered into the intrathecal (i.t.) space and also into brainstem circulation via the vertebral artery. Cumulative doses of i.t. baclofen or codeine had no effect on PS, abdominal muscle EMGs or cough number during the TB cough. Subsequent intra-arterial (i.a.) administration of baclofen or codeine significantly reduced magnitude of abdominal and PS muscles during TB cough. Furthermore, TB cough number was significantly suppressed by i.a. baclofen. The influence of these drugs on other behaviors that activate abdominal motor pathways was also assessed. The abdominal EMG response to noxious pinch of the tail was suppressed by i.t. baclofen, suggesting that the doses of baclofen that were employed were sufficient to affect spinal pathways. However, the abdominal EMG response to expiratory threshold loading was unaffected by i.t. administration of either baclofen or codeine. These results indicate that neither baclofen nor codeine suppress cough via a spinal action and support the concept that the antitussive effect of these drugs is restricted to the brainstem.
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Zhang M, Zhu Y, Dong R, Qiu Z. Gabapentin versus baclofen for treatment of refractory gastroesophageal reflux-induced chronic cough. J Thorac Dis 2020; 12:5243-5250. [PMID: 33145100 PMCID: PMC7578446 DOI: 10.21037/jtd-2020-icc-002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Refractory gastroesophageal reflux-induced chronic cough (GERC) is a special type of gastroesophageal reflux disease (GERD) with predominant cough resistant to pragmatic standard anti-reflux therapy including antisecretory agents alone or in combination with promotility agents but with a favorable response to intensified anti-reflux treatment. The condition is not rare and is difficult to treat. Neuromodulators such as baclofen and gabapentin are considered potential therapeutic options for refractory GERC. Limited data indicate that gabapentin and baclofen could attenuate the cough symptom in patients with refractory GERC by blockade of gastroesophageal reflux or by direct antitussive effects. However, no study has compared the efficacy of these two drugs in treatment of refractory GERC. In an open-labeled randomized clinical study, we demonstrated that, as add-on therapy, gabapentin and baclofen had a similar prevalence of therapeutic success for suspected refractory GERC but gabapentin may be more preferable because of its fewer central side effects. The efficacy of baclofen and gabapentin was suboptimal, so further studies are needed to select the patients with refractory GERC suitable for precise treatment using these two neuromodulators.
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Affiliation(s)
- Mengru Zhang
- Department of Pulmonary and Critical Care Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yiqing Zhu
- Department of Pulmonary and Critical Care Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Ran Dong
- Department of Pulmonary and Critical Care Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Zhongmin Qiu
- Department of Pulmonary and Critical Care Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
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Wong MW, Hung JS, Liu TT, Yi CH, Lei WY, Chen CL. Gamma-aminobutyric acid receptor type B agonist baclofen inhibits acid-induced excitation of secondary peristalsis but not heartburn sensation. J Gastroenterol Hepatol 2019; 34:370-375. [PMID: 30069912 DOI: 10.1111/jgh.14404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/02/2018] [Accepted: 07/25/2018] [Indexed: 12/09/2022]
Abstract
BACKGROUND AND AIM Acute esophageal acid infusion promotes distension-induced secondary peristalsis. The gamma-aminobutyric acid receptor type B (GABA-B) receptors activation inhibits secondary peristalsis. This study aimed to test the hypothesis whether acid excitation of secondary peristalsis can be influenced by baclofen. METHODS Secondary peristalsis was performed with intra-esophageal slow and rapid air injections in 13 healthy subjects. Direct esophageal infusion of 0.1 N HCl following pretreatment with placebo or baclofen was randomly performed at least 1 week apart. Symptom intensity, distension thresholds, and peristaltic parameters were determined and compared between each study protocol. RESULTS The intensity of heartburn symptom in response to esophageal acid infusion was significantly greater with baclofen than the placebo (P = 0.002). The threshold volume of secondary peristalsis during slow air injections in response to acid infusion was significantly greater with baclofen than the placebo (P = 0.001). Baclofen significantly increased the threshold volume of secondary peristalsis during rapid air injections in response to acid infusion (P = 0.001). The frequency of secondary peristalsis in response to acid infusion was significantly decreased by baclofen as compared with the placebo (P = 0.001). Baclofen significantly decreased peristaltic amplitudes in response to acid infusion during rapid air injections (P = 0.007). CONCLUSIONS Gamma-aminobutyric acid receptor type B agonist baclofen inhibits acid excitation of secondary peristalsis in human esophagus, which is probably mediated by both muscular and mucosal mechanoreceptors. This work supports the evidence of potential involvement of GABA-B receptors in negative modulation of acid excitation of esophageal perception as well as secondary peristalsis.
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Affiliation(s)
- Ming-Wun Wong
- Department of Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation and Tzu Chi University.,PhD Program in Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan
| | - Jui-Sheng Hung
- Department of Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation and Tzu Chi University
| | - Tso-Tsai Liu
- Department of Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation and Tzu Chi University
| | - Chih-Hsun Yi
- Department of Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation and Tzu Chi University
| | - Wei-Yi Lei
- Department of Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation and Tzu Chi University
| | - Chien-Lin Chen
- Department of Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation and Tzu Chi University
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El‐Hashim AZ, Mathews S, Al‐Shamlan F. Central adenosine A 1 receptors inhibit cough via suppression of excitatory glutamatergic and tachykininergic neurotransmission. Br J Pharmacol 2018; 175:3162-3174. [PMID: 29767468 PMCID: PMC6031887 DOI: 10.1111/bph.14360] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 03/02/2018] [Accepted: 04/10/2018] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND AND PURPOSE The adenosine A1 receptor is reported to mediate several excitatory effects in the airways and has inhibitory effects in the CNS. In this study, we investigated the role of peripheral and central A1 receptors in regulating cough and airway obstruction. EXPERIMENTAL APPROACH Drugs were administered to guinea pigs via inhalation or i.c.v. infusion. Following the administration of different drugs, cough was induced by exposing guinea pigs to aerosolized 0.4 M citric acid. An automated analyser recorded both cough and airway obstruction simultaneously using whole-body plethysmography. KEY RESULTS The A1 receptor agonist, cyclopentyladenosine (CPA, administered by inhalation), dose-dependently inhibited cough and also inhibited airway obstruction. Similarly, CPA, administered i.c.v., inhibited both the citric acid-induced cough and airway obstruction; this was prevented by pretreatment with the A1 receptor antagonist DPCPX (i.c.v.). Treatment with DPCPX alone dose-dependently enhanced the citric acid-induced cough and airway obstruction. This effect was reversed following treatment with either the glutamate GluN1 receptor antagonist D-AP5 or the neurokinin NK1 receptor antagonist FK-888. CONCLUSIONS AND IMPLICATIONS These findings suggest that activation of either peripheral or central adenosine A1 receptors inhibits citric acid-induced cough and airway obstruction. The data also suggest that tonic activation of central adenosine A1 receptors serves as a negative regulator of cough and airway obstruction, secondary to inhibition of excitatory glutamatergic and tachykininergic neurotransmission.
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Affiliation(s)
- Ahmed Z El‐Hashim
- Department of Pharmacology and Therapeutics, Faculty of PharmacyKuwait UniversityKuwait
| | - Seena Mathews
- Department of Pharmacology and Therapeutics, Faculty of PharmacyKuwait UniversityKuwait
| | - Fajer Al‐Shamlan
- Department of Pharmacology and Therapeutics, Faculty of PharmacyKuwait UniversityKuwait
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7
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Influence of GABA-B Agonist Baclofen on Capsaicin-Induced Excitation of Secondary Peristalsis in Humans. Clin Transl Gastroenterol 2017; 8:e120. [PMID: 28981081 PMCID: PMC5666117 DOI: 10.1038/ctg.2017.46] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/15/2017] [Indexed: 12/28/2022] Open
Abstract
OBJECTIVES Esophageal instillation of capsaicin enhances secondary peristalsis, but the γ-aminobutyric acid receptor type B (GABA-B) agonist baclofen inhibits secondary peristalsis. This study aimed to investigate whether baclofen could influence heartburn perception and secondary peristalsis subsequent to capsaicin infusion in healthy adults. METHODS Secondary peristalsis was performed by slow and rapid mid-esophagus air injections in 15 healthy subjects. Two different sessions including esophageal infusion of capsaicin-containing red pepper sauce (0.84 mg) following pre-treatment with placebo or baclofen were randomly performed to test the effects on heartburn perception and secondary peristalsis. RESULTS The intensity of heartburn symptom subsequent to capsaicin infusion was significantly greater after pre-treatment of baclofen as compared with the placebo (P=0.03). Baclofen significantly increased the threshold volume of secondary peristalsis to slow air injections subsequent to esophageal capsaicin infusion (P<0.001). Baclofen significantly increased the threshold volume of secondary peristalsis to rapid air injections subsequent to esophageal capsaicin infusion (P<0.01). The frequency of secondary peristalsis subsequent to capsaicin infusion was significantly decreased with baclofen as compared with the placebo (P<0.002). Baclofen had no effect on any of the peristaltic parameters of secondary peristalsis subsequent to capsaicin infusion. CONCLUSIONS The GABA-B agonist baclofen appears to attenuate the esophagus to capsaicin-induced excitation of secondary peristalsis in healthy adults. Our study suggests the inhibitory modulation for GABA-B receptors on capsaicin-sensitive afferents mediating secondary peristalsis in human esophagus.
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Pitts T, Morris KF, Segers LS, Poliacek I, Rose MJ, Lindsey BG, Davenport PW, Howland DR, Bolser DC. Feed-forward and reciprocal inhibition for gain and phase timing control in a computational model of repetitive cough. J Appl Physiol (1985) 2016; 121:268-78. [PMID: 27283917 PMCID: PMC4967248 DOI: 10.1152/japplphysiol.00790.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 06/08/2016] [Indexed: 11/22/2022] Open
Abstract
We investigated the hypothesis, motivated in part by a coordinated computational cough network model, that second-order neurons in the nucleus tractus solitarius (NTS) act as a filter and shape afferent input to the respiratory network during the production of cough. In vivo experiments were conducted on anesthetized spontaneously breathing cats. Cough was elicited by mechanical stimulation of the intrathoracic airways. Electromyograms of the parasternal (inspiratory) and rectus abdominis (expiratory) muscles and esophageal pressure were recorded. In vivo data revealed that expiratory motor drive during bouts of repetitive coughs is variable: peak expulsive amplitude increases from the first cough, peaks about the eighth or ninth cough, and then decreases through the remainder of the bout. Model simulations indicated that feed-forward inhibition of a single second-order neuron population is not sufficient to account for this dynamic feature of a repetitive cough bout. When a single second-order population was split into two subpopulations (inspiratory and expiratory), the resultant model produced simulated expiratory motor bursts that were comparable to in vivo data. However, expiratory phase durations during these simulations of repetitive coughing had less variance than those in vivo. Simulations in which reciprocal inhibitory processes between inspiratory-decrementing and expiratory-augmenting-late neurons were introduced exhibited increased variance in the expiratory phase durations. These results support the prediction that serial and parallel processing of airway afferent signals in the NTS play a role in generation of the motor pattern for cough.
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Affiliation(s)
- Teresa Pitts
- Department of Neurologic Surgery and Kentucky Spinal Cord Injury Research Center, College of Medicine, University of Louisville, Louisville, Kentucky; Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida;
| | - Kendall F Morris
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida; and
| | - Lauren S Segers
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida; and
| | - Ivan Poliacek
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida; Institute of Medical Biophysics, Jessenius Faculty of Medicine, Comenius University, Martin, Slovak Republic
| | - Melanie J Rose
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida
| | - Bruce G Lindsey
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida; and
| | - Paul W Davenport
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida
| | - Dena R Howland
- Department of Neurologic Surgery and Kentucky Spinal Cord Injury Research Center, College of Medicine, University of Louisville, Louisville, Kentucky
| | - Donald C Bolser
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida
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NMDA and GABA receptors as potential targets in cough hypersensitivity syndrome. Curr Opin Pharmacol 2015; 22:29-36. [DOI: 10.1016/j.coph.2015.03.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 03/02/2015] [Accepted: 03/02/2015] [Indexed: 12/21/2022]
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McGarvey L. Update: the search for the human cough receptor. Lung 2014; 192:459-65. [PMID: 24770379 DOI: 10.1007/s00408-014-9581-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 03/29/2014] [Indexed: 10/25/2022]
Abstract
Despite the best efforts of basic and applied science, the identity of the human "cough receptor" remains elusive. The attraction of identifying a single "catch all" cough receptor is obvious, although such an objective is unlikely to be realised given the concept of "cough hypersensitivity," which is now considered the most clinically relevant description of what underlies problem coughing. One means of progressing this area is to join the thinking and experimental effort of basic science and clinical research in an effective manner. Some of the best examples of cooperative and translational research over the years together with an update on the most recent work will be discussed in this article.
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Affiliation(s)
- Lorcan McGarvey
- Centre for Infection and Immunity, Queens University Belfast, Health Sciences Building, Lisburn Road, Belfast, BT9 7BL, Northern Ireland,
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Dicpinigaitis PV, Morice AH, Birring SS, McGarvey L, Smith JA, Canning BJ, Page CP. Antitussive drugs--past, present, and future. Pharmacol Rev 2014; 66:468-512. [PMID: 24671376 PMCID: PMC11060423 DOI: 10.1124/pr.111.005116] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Cough remains a serious unmet clinical problem, both as a symptom of a range of other conditions such as asthma, chronic obstructive pulmonary disease, gastroesophageal reflux, and as a problem in its own right in patients with chronic cough of unknown origin. This article reviews our current understanding of the pathogenesis of cough and the hypertussive state characterizing a number of diseases as well as reviewing the evidence for the different classes of antitussive drug currently in clinical use. For completeness, the review also discusses a number of major drug classes often clinically used to treat cough but that are not generally classified as antitussive drugs. We also reviewed a number of drug classes in various stages of development as antitussive drugs. Perhaps surprising for drugs used to treat such a common symptom, there is a paucity of well-controlled clinical studies documenting evidence for the use of many of the drug classes in use today, particularly those available over the counter. Nonetheless, there has been a considerable increase in our understanding of the cough reflex over the last decade that has led to a number of promising new targets for antitussive drugs being identified and thus giving some hope of new drugs being available in the not too distant future for the treatment of this often debilitating symptom.
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Affiliation(s)
- P V Dicpinigaitis
- King's College London, Franklin Wilkins Building, 100 Stamford St., London, SE1 9NH, UK.
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12
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Castillo D, Pitts T. Influence of baclofen on laryngeal and spinal motor drive during cough in the anesthetized cat. Laryngoscope 2013; 123:3088-92. [PMID: 23670824 DOI: 10.1002/lary.24143] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 03/18/2013] [Accepted: 03/18/2013] [Indexed: 11/07/2022]
Abstract
OBJECTIVES/HYPOTHESIS The antitussive properties of (±) baclofen on laryngeal muscle activities have not been determined. The hypothesis of this study was that administration of (±) baclofen would suppress upper airway muscle motor activity in a dose-dependent manner during cough. STUDY DESIGN This is a prospective, preclinical, hypothesis-driven, paired design. METHODS Electromyograms of the parasternal, rectus abdominis, thyroarytenoid, posterior cricoarytenoid, and thyrohyoid were measured, along with esophageal pressure. Cough was elicited by mechanical stimulation of the lumen of the intrathoracic trachea in spontaneously breathing cats. RESULTS Baclofen (±) (3-10 μg kg(-1) i.a.) induced decreases in the electromyogram amplitude of the rectus abdominis motor drive during coughing, the inspiratory and active expiratory (E1) phases of cough, and cough number per epoch. There was no effect of (±) baclofen on the EMG amplitudes of any of the laryngeal muscles, the parasternal, or the duration of the passive expiratory (E2) phase. CONCLUSIONS Results from the present study indicate differential control mechanisms for laryngeal and inspiratory motor drive during cough, providing evidence of a control system regulating laryngeal activity and inspiratory spinal drive that is divergent from the control of expiratory spinal motoneurons.
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Affiliation(s)
- Daniel Castillo
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, U.S.A
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Xu X, Chen Q, Liang S, Lü H, Qiu Z. Successful resolution of refractory chronic cough induced by gastroesophageal reflux with treatment of baclofen. COUGH 2012; 8:8. [PMID: 23078809 PMCID: PMC3500706 DOI: 10.1186/1745-9974-8-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Accepted: 10/01/2012] [Indexed: 12/18/2022]
Abstract
Gastroesophageal reflux induced cough is a common cause of chronic cough, and proton pump inhibitors are a standard therapy. However, the patients unresponsive to the standard therapy are difficult to treat and remain a challenge to doctors. Here, we summarized the experience of successful resolution of refractory chronic cough due to gastroesophageal reflux with baclofen in three patients. It is concluded that baclofen may be a viable option for gastroesophageal reflux induced cough unresponsive to proton pump inhibitor therapy.
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Affiliation(s)
- Xianghuai Xu
- Department of Respiratory Medicine, Tongji Hospital, Tongji University School of Medicine, No, 389 Xincun Road, Shanghai, 200065, China.
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Canning BJ, Mori N, Lehmann A. Antitussive effects of the peripherally restricted GABAB receptor agonist lesogaberan in guinea pigs: comparison to baclofen and other GABAB receptor-selective agonists. COUGH 2012; 8:7. [PMID: 23025757 PMCID: PMC3520872 DOI: 10.1186/1745-9974-8-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 09/07/2012] [Indexed: 12/17/2022]
Abstract
UNLABELLED BACKGROUND Gastroesophageal reflux disease (GERD) is a common cause of chronic cough. Both acid and nonacid reflux is thought to play a role in the initiation of coughing and cough hypersensitivity. The GABAB receptor agonist lesogaberan was developed as a peripherally restricted anti-reflux therapy that reduces the frequency of transient lower esophageal sphincter relaxations (TLESR; the major cause of reflux) in animals and in patients with GERD. GABAB receptor agonists have also been shown to possess antitussive effects in patients and in animals independent of their effects on TLESR, suggesting that lesogaberan may be a promising treatment for chronic cough. METHODS We have assessed the direct antitussive effects of lesogaberan (AZD3355). The effects of other GABAB receptor agonists were also determined. Coughing was evoked in awake guinea pigs using aerosol challenges with citric acid. RESULTS Lesogaberan dose-dependently inhibited citric acid evoked coughing in guinea pigs. Comparable effects of the GABAB receptor agonists baclofen and 3-aminopropylphosphinic acid (3-APPiA) on cough were also observed. Baclofen produced obvious signs of sedation and respiratory depression. By contrast, both lesogaberan and 3-APPiA (both inactivated centrally by GABA transporters) were devoid of sedative effects and did not alter respiratory rate. CONCLUSIONS Together, the data suggest that lesogaberan and related GABAB receptor agonists may hold promise as safe and effective antitussive agents largely devoid of CNS side effects.
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Affiliation(s)
- Brendan J Canning
- Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Baltimore, Maryland, 21224, USA.
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Lehmann A, Antonsson M, Aurell-Holmberg A, Blackshaw LA, Brändén L, Elebring T, Jensen J, Kärrberg L, Mattsson JP, Nilsson K, Oja SS, Saransaari P, von Unge S. Different in vitro and in vivo profiles of substituted 3-aminopropylphosphinate and 3-aminopropyl(methyl)phosphinate GABA(B) receptor agonists as inhibitors of transient lower oesophageal sphincter relaxation. Br J Pharmacol 2012; 165:1757-1772. [PMID: 21950457 DOI: 10.1111/j.1476-5381.2011.01682.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND AND PURPOSE Gastro-oesophageal reflux is predominantly caused by transient lower oesophageal sphincter relaxation (TLOSR) and GABA(B) receptor stimulation inhibits TLOSR. Lesogaberan produces fewer CNS side effects than baclofen, which has been attributed to its affinity for the GABA transporter (GAT), the action of which limits stimulation of central GABA(B) receptors. To understand the structure-activity relationship for analogues of lesogaberan (3-aminopropylphosphinic acids), and corresponding 3-aminopropyl(methyl)phosphinic acids, we have compared representatives of these classes in different in vitro and in vivo models. EXPERIMENTAL APPROACH The compounds were characterized in terms of GABA(B) agonism in vitro. Binding to GATs and cellular uptake was done using rat brain membranes and slices respectively. TLOSR was measured in dogs, and CNS side effects were evaluated as hypothermia in mice and rats. KEY RESULTS 3-Aminopropylphosphinic acids inhibited TLOSR with a superior therapeutic index compared to 3-aminopropyl(methyl)phosphinic acids. This difference was most likely due to differential GAT-mediated uptake into brain cells of the former but not latter. In agreement, 3-aminopropyl(methyl)phosphinic acids were much more potent in producing hypothermia in rats even when administered i.c.v. CONCLUSIONS AND IMPLICATIONS An enhanced therapeutic window for 3-aminopropylphosphinic acids compared with 3-aminopropyl(methyl)phosphinic acids with respect to inhibition of TLOSR was observed and is probably mechanistically linked to neural cell uptake of the former but not latter group of compounds. These findings offer a platform for discovery of new GABA(B) receptor agonists for the treatment of reflux disease and other conditions where selective peripheral GABA(B) receptor agonism may afford therapeutic effects.
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Affiliation(s)
- A Lehmann
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - M Antonsson
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - A Aurell-Holmberg
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - L A Blackshaw
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - L Brändén
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - T Elebring
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - J Jensen
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - L Kärrberg
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - J P Mattsson
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - K Nilsson
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - S S Oja
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - P Saransaari
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
| | - S von Unge
- AstraZeneca R&D, Mölndal, SwedenNerve Gut Research Laboratory, Hanson Institute, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, and University of Adelaide, South Australia, AustraliaDepartment of Paediatrics, Tampere University Hospital, FinlandBrain Research Center, Medical School, University of Tampere, Finland
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Chen CL, Liu TT, Yi CH. Control of esophageal distension-induced secondary peristalsis by the GABA(B) agonist baclofen in humans. Neurogastroenterol Motil 2011; 23:612-e250. [PMID: 21501336 DOI: 10.1111/j.1365-2982.2011.01716.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Secondary peristalsis is important for the clearance of retained food bolus or refluxate from the esophagus. The effects of the gamma aminobutyric acid receptor type B (GABA(B) ) agonist on secondary peristalsis remain unclear in humans. We aimed to investigate the effect of a GABA(B) agonist baclofen on esophageal secondary peristalsis. METHODS After a baseline recording of esophageal motility, secondary peristalsis was generated by slow and rapid mid-esophageal injections of air in 15 healthy subjects. Two separate sessions with 40mg oral baclofen or placebo were randomly performed to test their effects on secondary peristalsis. KEY RESULTS Baclofen increased the threshold volume for triggering secondary peristalsis during slow air distension (P=0.003) and rapid air distension (P=0.002). Baclofen reduced the rate of secondary peristalsis by rapid air distension from 90% to 30% (P=0.0002). Baclofen increased basal lower esophageal sphincter pressure (P=0.03). Baclofen did not affect any of peristaltic parameters during primary or secondary peristalsis. CONCLUSIONS & INFERENCES This study provides an evidence for inhibitory modulation of esophageal secondary peristalsis by the GABA(B) agonist baclofen. Activation of secondary peristalsis is probably modulated by GABA(B) receptors; however, baclofen does not lead to any motility change in secondary peristalsis.
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Affiliation(s)
- C L Chen
- Department of Medicine, Buddhist Tzu Chi General Hospital and Tzu Chi University, Hualien, Taiwan.
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Dicpinigaitis PV. Cough: an unmet clinical need. Br J Pharmacol 2011; 163:116-24. [PMID: 21198555 PMCID: PMC3085873 DOI: 10.1111/j.1476-5381.2010.01198.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 11/20/2010] [Accepted: 11/23/2010] [Indexed: 12/13/2022] Open
Abstract
Cough is among the most common complaints for which patients worldwide seek medical attention. Thus, the evaluation and treatment of cough result in tremendous financial expenditure and consumption of health care resources. Yet, despite the clinical significance of cough, research efforts aimed at improving diagnostic capabilities and developing more effective therapeutic agents have been, to date, disappointing in their limited scope and outcomes. Acute cough due to the common cold represents the most common type of cough. Currently, available medications for the symptomatic management of acute cough are inadequate due to lack of proven efficacy and/or their association with undesirable or intolerable side effects at anti-tussive doses. Subacute cough, often representing a prolonged post-viral response, is typically refractory to standard anti-tussive therapy. Few clinical trials have evaluated therapeutic options for subacute cough. Diagnostic challenges facing the clinician in the management of chronic cough include the determination of whether symptoms of upper airway cough syndrome (formerly, postnasal drip syndrome) or gastro-oesophageal reflux disease are indeed the underlying cause of cough. Chronic, refractory unexplained (formerly, idiopathic) cough must be distinguished from cough that has not been fully evaluated and treated according to current guideline recommendations. Eagerly awaited are new safe and effective anti-tussive agents for use when cough suppression is desired, regardless of underlying aetiology of cough, as well as practical, validated ambulatory cough counters to aid clinical assessment and future research in the field of cough.
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Affiliation(s)
- Peter V Dicpinigaitis
- Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY 10461, USA.
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18
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Cough following low thoracic hemisection in the cat. Exp Neurol 2010; 222:165-70. [PMID: 20043908 DOI: 10.1016/j.expneurol.2009.12.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 12/14/2009] [Accepted: 12/17/2009] [Indexed: 01/15/2023]
Abstract
A function of the abdominal expiratory muscles is the generation of cough, a critical respiratory defense mechanism that is often disrupted following spinal cord injury. We assessed the effects of a lateral T9/10 hemisection on cough production at 4, 13 and 21 weeks post-injury in cats receiving extensive locomotor training. The magnitudes of esophageal pressure as well as of bilateral rectus abdominis electromyogram activity during cough were not significantly different from pre-injury values at all time points evaluated. The results show that despite considerable interruption of the descending pre-motor drive from the brainstem to the expiratory motoneuron pools, the cough motor system shows a significant function by 4 weeks following incomplete thoracic injury.
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Wang C, Saha S, Rose MJ, Davenport PW, Bolser DC. Spatiotemporal regulation of the cough motor pattern. Cough 2009; 5:12. [PMID: 20028523 PMCID: PMC2807847 DOI: 10.1186/1745-9974-5-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 12/22/2009] [Indexed: 11/21/2022] Open
Abstract
The purpose of this study was to identify the spatiotemporal determinants of the cough motor pattern. We speculated that the spatial and temporal characteristics of the cough motor pattern would be regulated separately. Electromyograms (EMG) of abdominal muscles (ABD, rectus abdominis or transversus abdominis), and parasternal muscles (PS) were recorded in anesthetized cats. Repetitive coughing was produced by mechanical stimulation of the lumen of the intrathoracic trachea. Cough inspiratory (CT(I)) and expiratory (CT(E)) durations were obtained from the PS EMG. The ABD EMG burst was confined to the early part of CT(E )and was followed by a quiescent period of varying duration. As such, CT(E )was divided into two segments with CT(E1 )defined as the duration of the ABD EMG burst and CT(E2 )defined as the period of little or no EMG activity in the ABD EMG. Total cough cycle duration (CT(TOT)) was strongly correlated with CT(E2 )(r(2)>0.8), weakly correlated with CT(I )(r(2)<0.3), and not correlated with CT(E1 )(r(2)<0.2). There was no significant relationship between CT(I )and CT(E1 )or CT(E2). The magnitudes of inspiratory and expiratory motor drive during cough were only weakly correlated with each other (r(2)<0.36) and were not correlated with the duration of any phase of cough. The results support: a) separate regulation of CT(I )and CT(E), b) two distinct subphases of CT(E )(CT(E1 )and CT(E2)), c) the duration of CT(E2 )is a primary determinant of CT(TOT), and d) separate regulation of the magnitude and temporal features of the cough motor pattern.
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Affiliation(s)
- Cheng Wang
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, 32610, USA
| | - Sourish Saha
- Department of Statistics, College of Liberal Arts and Sciences, University of Florida, Gainesville, Florida, 32611, USA
| | - Melanie J Rose
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, 32610, USA
| | - Paul W Davenport
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, 32610, USA
| | - Donald C Bolser
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, 32610, USA
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20
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Pharmacological profile of the NOP agonist and cough suppressing agent SCH 486757 (8-[Bis(2-Chlorophenyl)Methyl]-3-(2-Pyrimidinyl)-8-Azabicyclo[3.2.1]Octan-3-Ol) in preclinical models. Eur J Pharmacol 2009; 630:112-20. [PMID: 20006596 DOI: 10.1016/j.ejphar.2009.12.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 11/19/2009] [Accepted: 12/03/2009] [Indexed: 10/20/2022]
Abstract
We describe the pharmacological and pharmacokinetic profiles of SCH 486757, a nociceptin/orphanin FQ peptide (NOP) receptor agonist that has recently entered human clinical trials for cough. SCH 486757 selectively binds human NOP receptor (K(i)=4.6+/-0.61nM) over classical opioid receptors. In a guinea pig capsaicin cough model, SCH 486757 (0.01-1mg/kg) suppressed cough at 2, 4, and 6h post oral administration with a maximum efficacy occurring at 4h equivalent to codeine, hydrocodone, dextromethorphan and baclofen. The antitussive effects of SCH 486757 (3.0mg/kg, p.o.) was blocked by the NOP receptor antagonist J113397 (12mg/kg, i.p.) but not by naltrexone (10mg/kg, p.o.). SCH 486757 does not produce tolerance to its antitussive activity after a 5-day BID dosing regimen. After acute and chronic dosing paradigms, SCH 486757 (1mg/kg) inhibited capsaicin-evoked coughing by 46+/-9% and 40+/-11%, respectively. In a feline mechanically-evoked cough model, SCH 486757 produces a maximum inhibition of cough and expiratory abdominal electromyogram amplitude of 59 and 61%, respectively. SCH 486757 did not significantly affect inspiratory electromyogram amplitude. We examined the abuse potential of SCH 486757 (10mg/kg, p.o.) in a rat conditioned place preference procedure which is sensitive to classical drugs of abuse, such as amphetamine and morphine. SCH 486757 was without effect in this model. Finally, SCH 486757 displays a good oral pharmacokinetic profile in the guinea pig, rat and dog. We conclude that SCH 486757 has a favorable antitussive profile in preclinical animal models.
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21
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Modulation of sensory nerve function and the cough reflex: understanding disease pathogenesis. Pharmacol Ther 2009; 124:354-75. [PMID: 19818366 DOI: 10.1016/j.pharmthera.2009.09.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Accepted: 09/16/2009] [Indexed: 12/29/2022]
Abstract
To cough is a protective defence mechanism that is vital to remove foreign material and secretions from the airways and which in the normal state serves its function appropriately. Modulation of the cough reflex pathway in disease can lead to inappropriate chronic coughing and an augmented cough response. Chronic cough is a symptom that can present in conjunction with a number of diseases including chronic obstructive pulmonary disease (COPD) and asthma, although often the cause of chronic cough may be unknown. As current treatments for cough have proved to exhibit little efficacy and are largely ineffective, there is a need to develop novel, efficacious and safe antitussive therapies. The underlying mechanisms of the cough reflex are complex and involve a network of events, which are not fully understood. It is accepted that the cough reflex is initiated following activation of airway sensory nerves. Therefore, in the hope of identifying novel antitussives, much research has focused on understanding the neural mechanisms of cough provocation. Experimentally this has been undertaken using chemical or mechanical tussive stimuli in conjunction with animal models of cough and clinical cough assessments. This review will discuss the neural mechanisms involved in the cough, changes that occur under pathophysiological conditions and and how current research may lead to novel therapeutic opportunities for the treatment of cough.
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Dicpinigaitis PV. Currently available antitussives. Pulm Pharmacol Ther 2009; 22:148-51. [DOI: 10.1016/j.pupt.2008.08.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Accepted: 08/09/2008] [Indexed: 02/08/2023]
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Abstract
Following systemic administration, centrally acting antitussive drugs are generally assumed to act in the brainstem to inhibit cough. However, recent work in humans has raised the possibility of suprapontine sites of action for cough suppressants. For drugs that may act in the brainstem, the specific locations, types of neurones affected, and receptor specificities of the compounds represent important issues regarding their cough-suppressant actions. Two medullary areas that have received the most attention regarding the actions of antitussive drugs are the nucleus of the tractus solitarius (NTS) and the caudal ventrolateral respiratory column. Studies that have implicated these two medullary areas have employed both microinjection and in vitro recording methods to control the location of action of the antitussive drugs. Other brainstem regions contain neurones that participate in the production of cough and could represent potential sites of action of antitussive drugs. These regions include the raphe nuclei, pontine nuclei, and rostral ventrolateral medulla. Specific receptor subtypes have been associated with the suppression of cough at central sites, including 5-HT1A, opioid (mu, kappa, and delta), GABA-B, tachykinin neurokinin-1 (NK-1) and neurokinin-2, non-opioid (NOP-1), cannabinoid, dopaminergic, and sigma receptors. Aside from tachykinin NK-1 receptors in the NTS, relatively little is known regarding the receptor specificity of putative antitussive drugs in particular brainstem regions. Our understanding of the mechanisms of action of antitussive drugs would be significantly advanced by further work in this area.
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Affiliation(s)
- D C Bolser
- Department of Physiological Sciences, University of Florida, College of Veterinary Medicine, Gainesville, FL 32610-0144, USA.
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Affiliation(s)
- A H Morice
- University of Hull, Castle Hill Hospital, Cottingham, East Yorkshire HU16 5JQ, UK.
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Bolser DC. Current and future centrally acting antitussives. Respir Physiol Neurobiol 2006; 152:349-55. [PMID: 16517221 PMCID: PMC3131070 DOI: 10.1016/j.resp.2006.01.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 01/24/2006] [Accepted: 01/27/2006] [Indexed: 11/15/2022]
Abstract
The purpose of this review is to highlight some important issues regarding current centrally acting antitussive drugs as well as discuss the implications of these matters on the development of future cough suppressants. Drugs that act in the central nervous system to inhibit cough are termed centrally acting and this designation is based exclusively on evidence obtained from animal models. This classification can include drugs that act both at peripheral and central sites following systemic administration. These drugs are intended to reduce the frequency and/or intensity of coughing resulting from disorders of any etiology. There are a number of central cough suppressants identified by their efficacy in animal models and the most prominent of these are codeine and dextromethorphan. Although the exact neural elements on which these drugs act are currently unknown, they are thought to inhibit a functionally identified component of the central system for cough known as the gating mechanism. The efficacy of codeine and dextromethorphan in humans has recently been questioned. These drugs are less effective on cough induced by upper airway disorders than in pathological conditions involving the lower airways in humans. The reasons for this difference in antitussive sensitivity are not clear. We propose that sensory afferents from different regions of the airways actuate coughing in humans by antitussive sensitive and insensitive control elements in the central nervous system. This hypothesis is consistent with results from an animal model in which laryngeal and tracheobronchial cough had different sensitivities to codeine. Other factors that may be very important in the action of central antitussive drugs in humans include the role of sensations produced by a tussigenic stimulus as well as plasticity of central pathways in response to airway inflammation. Resolution of these issues in the human will be a challenging process, but one which will lay the foundation for the development of more effective cough suppressants.
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Affiliation(s)
- Donald C Bolser
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
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Ohi Y, Yamazaki H, Takeda R, Haji A. Functional and morphological organization of the nucleus tractus solitarius in the fictive cough reflex of guinea pigs. Neurosci Res 2005; 53:201-9. [PMID: 16040147 DOI: 10.1016/j.neures.2005.06.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Revised: 06/09/2005] [Accepted: 06/22/2005] [Indexed: 11/26/2022]
Abstract
Projection of the superior laryngeal nerve (SLN) afferent fibers into the nucleus tractus solitarius (NTS) was investigated using a fluorescent tracer in guinea pigs. High density of fluorescence was detected in the ipsilateral NTS extending from 0.5 mm caudal to 1.2 mm rostral to the obex. At coronal slices, the fluorescent granules, lines and patches were located in the interstitial, medial and dorsal regions of NTS. Fluorescence was also found in the dorsal region of contralateral commissural NTS. Microstimulation of the rostral NTS, which corresponded to the region showing the strong fluorescence, induced an increase in the inspiratory discharge of phrenic nerve that was immediately followed by a large burst discharge of the iliohypogastric nerve in decerebrate, paralyzed and artificially ventilated guinea pigs. This serial response of the two nerves was identical to that induced by electrical stimulation of the SLN. Intravenous injection of codeine suppressed both NTS and SLN-induced responses. The SLN-induced response was inhibited by microinjection of codeine into the ipsilateral NTS and abolished by lesion of the ipsilateral NTS. These results suggest that the NTS has an integrative function in production of cough reflex and is possible sites of action of central antitussive agents.
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Affiliation(s)
- Yoshiaki Ohi
- Department of Pharmacology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama 930-0194, Japan
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Abstract
Enhanced coughing can be produced in a variety of animal models, including the guinea pig, cat, dog and pig. Typically, airway inflammation has been produced by sensitization, exposure to cigarette smoke, sulphur dioxide or angiotensin-converting enzyme inhibitors. In some of these models, inflammatory mediators such as bradykinin and tachykinins have been shown to contribute to the enhanced coughing. While most of these studies have focussed on peripheral mechanisms, increases in central excitability of the cough reflex have been shown to occur as a result of airway inflammation. As such, we propose that enhanced coughing in pathological conditions is the result of plastic changes in both peripheral and central neural elements. Furthermore, we present a modified model of the neurogenesis of cough that takes into account peripheral and central plasticity induced by mediators of inflammation.
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Affiliation(s)
- Donald C Bolser
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, P.O. Box 100144, Gainesville, FL 32610-0144, USA.
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Ebrahimi SA, Zareie MR, Rostami P, Mahmoudian M. Interaction of noscapine with the bradykinin mediation of the cough response. ACTA PHYSIOLOGICA HUNGARICA 2004; 90:147-55. [PMID: 12903913 DOI: 10.1556/aphysiol.90.2003.2.7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Angiotensin Converting Enzyme Inhibitors (ACEI) like captopril and enalapril, can induce persistant cough in man. Noscapine, an antitussive alkaloid, can be used to suppress ACEI-induced cough. Some workers have suggested a role for bradykinin in precipitation of ACE-induced cough. Work carried out in our laboratory has shown noscapine to be a non-competitive inhibitor of bradykinin in guinea pig ileum. It is therefore possible that noscapine suppresses cough by blocking the effect of bradykinin receptor activation in the airways. Guinea pigs were placed in a cough-chamber connected to an air pump and a pressure transducer. Capsaicin was sprayed into the chamber and cough was recorded as a distinctive change in air pressure inside the cough-chamber. Animals treated with 1 mg/kg captopril and enalapril for 7 days, showed increased cough response. Ten microgram/kg FR190997, a non-peptide agonist of the bradykinin B2 receptor, also increased the cough response. Noscapine at 0.5, 1 and 2 mg/kg was able to reverse the effects of ACEI and FR190997. Naloxone, a specific opioid receptor inhibitor, did not block the antitussive effects of noscapine in enalapril or FR190997 treated guinea pigs. This antitussive effect of noscapine is not mediated via the mu, kappa or delta opioid receptors. It is therefore possible that noscapine exerts its antitussive action by interfering with the bradykinin cough mediation.
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Affiliation(s)
- S A Ebrahimi
- Razi Institute for Drug Research, Iran University for Medical Sciences, Tehran, Iran
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Mahmoudian M, Siadatpour Z, Ziai SA, Mehrpour M, Benaissa F, Nobakht M. Reduction of the prenatal hypoxic-ischemic brain edema with noscapine. ACTA ACUST UNITED AC 2003; 90:313-8. [PMID: 14708873 DOI: 10.1556/aphysiol.90.2003.4.4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cytotoxic free radicals and release of several neurotransmitters such as bradykinin contribute to the pathogenesis of hypoxic-ischemic brain damage. We have studied the efficacy of noscapine, an opium alkaloid and a bradykinin antagonist, in reducing post-hypoxic-ischemic damage in developing brain of 7-d-old rat pups. Hypoxic-ischemic injury to the right cerebral hemisphere was produced by legation of the right common carotid artery followed by 3 h of hypoxia with 8% oxygen. Thirty to 45 min before hypoxia the rat pups received noscapine (dose = 0.5-2 mg/kg) or saline. Pups were scarified at 24 h post recovery for the assessment of cerebral damage by histological methods. Our results showed that noscapine was an effective agent in reducing the extent of brain injury after hypoxic-ischemic insult to neonatal rats. Therefore, it is concluded that noscapine may be a useful drug in the managements of patients after stroke.
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Affiliation(s)
- M Mahmoudian
- Razi Institute for Drug Research, Iran University of Medical Sciences, Tehran, Iran
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Affiliation(s)
- Maria G Belvisi
- Respiratory Pharmacology Group, Cardiothoracic Surgery, National Heart & Lung Institute, Faculty of Medicine, Imperial College of Science, Technology & Medicine, London, UK
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Abstract
Cough is an important defensive reflex of the upper airway and is also a very common symptom of respiratory disease. Cough following an upper respiratory viral infection is transient, and persistent cough is associated with a whole range of conditions, such as asthma, rhino-sinusitis and gastro-oesophageal reflux. Treatment directed at these conditions may improve the associated cough. There is often a need, however, to control cough itself whatever the cause. The most effective drugs in this class are the opioids, such as morphine, codeine or pholcodeine, but at effective doses they have side effects including drowsiness, nausea, constipation and physical dependence. Investigations into the cough reflex and into the potential mechanisms of sensitised cough reflex have uncovered several potential targets for novel drugs. New opioids apart from mu-agonists such as kappa- and delta -receptor agonists, have been developed, in addition to non-opioids such as nociceptin. Neurokinin receptor antagonists, bradykinin receptor antagonists, vanniloid receptor VR-1 antagonists may be beneficial by blocking effects of tachykinins and sensory nerve activation. Local anaesthetics, blockers of sodium-dependent channels and maxi-K Ca2+-dependent channel activators of afferent nerves are inhibitors of the cough reflex. Some of these novel agents may act centrally or peripherally or at both sites as antitussives. Large scale trials of these novel compounds have not been carried out in cough in man but there is a serious need for more effective antitussives devoid of side effects.
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Affiliation(s)
- K F Chung
- National Heart & Lung Institute, Imperial College, Dovehouse Street, London SW3 6LY, UK.
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McLeod RL, Bolser DC, Jia Y, Parra LE, Mutter JC, Wang X, Tulshian DB, Egan RW, Hey JA. Antitussive effect of nociceptin/orphanin FQ in experimental cough models. Pulm Pharmacol Ther 2002; 15:213-6. [PMID: 12099766 DOI: 10.1006/pupt.2002.0357] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cough is an important defensive pulmonary reflex that removes irritants, fluids or foreign materials from the airways. However, often cough is non-productive and requires suppression. Opioid mu receptor agonists, such as codeine are commonly used as antitussive agents and are among the most widely administered drugs in the world. Codeine suppresses the responsiveness of one or more components of the central reflex pathway for cough and is an efficacious antitussive drug for cough due to diverse aetiologies. However, opioids produce side effects that include sedation, addiction potential and constipation. Therefore, novel cough suppressant therapies should maintain or improve upon the antitussive efficacy profile of opioids. Moreover, these novel therapies should have a safety profile significantly better than current antitussive therapies. Presently, we discuss preclinical findings showing that activation of the 'opioid-like' receptor (NOP(1)) inhibits cough in the guinea pig and cat.
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Affiliation(s)
- Robbie L McLeod
- Department of Allergy, Schering-Plough Research Institute, Kenilworth, NJ, 07033-0539, USA.
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Abstract
Experiments were conducted to determine the influence of the specific ORL1 receptor agonist, nociceptin, on the cough reflex in the cat. Cats were anesthetized and allowed to breathe spontaneously. Cough was elicited by mechanical stimulation of the intrathoracic airway. Intravenous administration of nociceptin (0.001-3.0 mg x kg(-1)) inhibited cough number and the magnitude of abdominal muscle electromyogram (EMG) discharge during cough in a dose-dependent manner. Nociceptin had no effect on the magnitude of the inspiratory muscle EMG during cough. These effects of nociceptin were antagonized by pretreatment with the ORL1 receptor antagonist, 1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1, 3-dihydro-2H-benzimidazol-2-one (J-113397, 0.1 mg x kg(-1), i.v.). We conclude that intravenous nociceptin inhibits cough in the cat.
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Affiliation(s)
- D C Bolser
- Department of Physiological Sciences, University of Florida, Gainesville, FL 32610-0144, USA.
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McLeod RL, Parra LE, Mutter JC, Erickson CH, Carey GJ, Tulshian DB, Fawzi AB, Smith-Torhan A, Egan RW, Cuss FM, Hey JA. Nociceptin inhibits cough in the guinea-pig by activation of ORL(1) receptors. Br J Pharmacol 2001; 132:1175-8. [PMID: 11250866 PMCID: PMC1572678 DOI: 10.1038/sj.bjp.0703954] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2000] [Revised: 01/15/2001] [Accepted: 01/16/2001] [Indexed: 11/08/2022] Open
Abstract
We studied the central and peripheral antitussive effect of ORL(1) receptor activation with nociceptin/orphanin FQ in conscious guinea-pigs. In guinea-pig cough studies, nociceptin/orphanin FQ (10, 30, and 90 microg) given directly into the CNS by an intracerebroventricular (i.c.v.) route inhibited cough elicited by capsaicin exposure by approximately 23, 29 and 52%, respectively. The antitussive activity of nociceptin/orphanin FQ (90 microg, i.c.v.) was blocked by the selective ORL(1) antagonist [Phe(1)gamma(CH(2)-NH)Gly(2)]nociceptin-(1-13)-NH(2) (180 microg, i.c.v.) and J113397 (10 mg kg(-1), i.p.) but not by the opioid antagonist, naltrexone (3 mg kg(-1), i.p.). Furthermore, intravenous (i.v.) nociceptin/orphanin FQ (1.0 and 3.0 mg kg(-1)) also inhibited cough approximately by 25 and 42%, respectively. These findings indicate that selective ORL(1) agonists display the potential to inhibit cough by both a central and peripheral mechanism, and potentially represent a novel therapeutic approach for the treatment of cough.
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Affiliation(s)
- R L McLeod
- Allergy, Schering-Plough Research Institute, Kenilworth, New Jersey, NJ 07033-0539, USA.
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Calver AR, Medhurst AD, Robbins MJ, Charles KJ, Evans ML, Harrison DC, Stammers M, Hughes SA, Hervieu G, Couve A, Moss SJ, Middlemiss DN, Pangalos MN. The expression of GABA(B1) and GABA(B2) receptor subunits in the cNS differs from that in peripheral tissues. Neuroscience 2001; 100:155-70. [PMID: 10996466 DOI: 10.1016/s0306-4522(00)00262-1] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
GABA(B) receptors are G-protein-coupled receptors that mediate the slow and prolonged synaptic actions of GABA in the CNS via the modulation of ion channels. Unusually, GABA(B) receptors form functional heterodimers composed of GABA(B1) and GABA(B2) subunits. The GABA(B1) subunit is essential for ligand binding, whereas the GABA(B2) subunit is essential for functional expression of the receptor dimer at the cell surface. We have used real-time reverse transcriptase-polymerase chain reaction to analyse expression levels of these subunits, and their associated splice variants, in the CNS and peripheral tissues of human and rat. GABA(B1) subunit splice variants were expressed throughout the CNS and peripheral tissues, whereas surprisingly GABA(B2) subunit splice variants were neural specific. Using novel antisera specific to individual GABA(B) receptor subunits, we have confirmed these findings at the protein level. Analysis by immunoblotting demonstrated the presence of the GABA(B1) subunit, but not the GABA(B2) subunit, in uterus and spleen. Furthermore, we have shown the first immunocytochemical analysis of the GABA(B2) subunit in the brain and spinal cord using a GABA(B2)-specific antibody. We have, therefore, identified areas of non-overlap between GABA(B1) and GABA(B2) subunit expression in tissues known to contain functional GABA(B) receptors. Such areas are of interest as they may well contain novel GABA(B) receptor subunit isoforms, expression of which would enable the GABA(B1) subunit to reach the cell surface and form functional GABA(B) receptors.
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Affiliation(s)
- A R Calver
- Department of Neuroscience Research, SmithKline Beecham Pharmaceuticals, New Frontiers Science Park, Third Avenue, Essex CM19 5AW, Harlow, UK.
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Bolser DC, Reier PJ, Davenport PW. Responses of the anterolateral abdominal muscles during cough and expiratory threshold loading in the cat. J Appl Physiol (1985) 2000; 88:1207-14. [PMID: 10749809 DOI: 10.1152/jappl.2000.88.4.1207] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study was conducted to determine the pattern of activation of the anterolateral abdominal muscles during the cough reflex. Electromyograms (EMGs) of the rectus abdominis, external oblique, internal oblique, transversus abdominis, and parasternal muscles were recorded along with gastric pressure in anesthetized cats. Cough was produced by mechanical stimulation of the lumen of the intrathoracic trachea or larynx. The pattern of EMG activation of these muscles during cough was compared with that during graded expiratory threshold loading (ETL; 1-30 cmH(2)O). ETL elicited differential recruitment of abdominal muscle EMG activity (transversus abdominis > internal oblique > rectus abdominis congruent with external oblique). In contrast, both laryngeal and tracheobronchial cough resulted in simultaneous activation of all four anterolateral abdominal muscles with peak EMG amplitudes 3- to 10-fold greater than those observed during the largest ETL. Gastric pressures during laryngeal and tracheobronchial cough were at least eightfold greater than those produced by the largest ETL. These results suggest that, unlike their behavior during expiratory loading, the anterolateral abdominal muscles act as a unit during cough.
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Affiliation(s)
- D C Bolser
- Department of Physiological Sciences, University of Florida, Gainesville, Florida 32612, USA.
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37
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Chapter 6. Recent developments in antitussive therapy. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2000. [DOI: 10.1016/s0065-7743(00)35007-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Karlsson JA, Fuller RW. Pharmacological regulation of the cough reflex--from experimental models to antitussive effects in Man. Pulm Pharmacol Ther 1999; 12:215-28. [PMID: 10500001 DOI: 10.1006/pupt.1999.0207] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- J A Karlsson
- Discovery Biology, Rhone-Poulene Rorer, Dagenham, UK
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Bolser DC, Hey JA, Chapman RW. Influence of central antitussive drugs on the cough motor pattern. J Appl Physiol (1985) 1999; 86:1017-24. [PMID: 10066718 DOI: 10.1152/jappl.1999.86.3.1017] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study was conducted to determine the effects of administration of centrally active antitussive drugs on the cough motor pattern. Electromyograms of diaphragm and rectus abdominis muscles were recorded in anesthetized, spontaneously breathing cats. Cough was produced by mechanical stimulation of the intrathoracic trachea. Centrally acting drugs administered included codeine, morphine, dextromethorphan, baclofen, CP-99,994, and SR-48,968. Intravertebral artery administration of all drugs reduced cough number (number of coughs per stimulus trial) and rectus abdominis burst amplitude in a dose-dependent manner. Codeine, dextromethorphan, CP-99,994, SR-48,968, and baclofen had no effect on cough cycle timing (CTtot) or diaphragm amplitude during cough, even at doses that inhibited cough number by 80-90%. Morphine lengthened CTtot and inhibited diaphragm amplitude during cough, but these effects were not dose dependent. Only CP-99,994 altered the eupneic respiratory pattern. Central antitussive drugs primarily suppress cough by inhibition of expiratory motor drive and cough number. CTtot and inspiratory motor drive are relatively insensitive to the effects of these drugs. CTtot can be controlled independently from cough number.
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Affiliation(s)
- D C Bolser
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32606, USA.
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40
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Bolser DC, Reier PJ. Inspiratory and expiratory patterns of the pectoralis major muscle during pulmonary defensive reflexes. J Appl Physiol (1985) 1998; 85:1786-92. [PMID: 9804582 DOI: 10.1152/jappl.1998.85.5.1786] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Experiments were conducted to determine the discharge pattern of the pectoralis major muscle during pulmonary defensive reflexes in anesthetized cats (n = 15). Coughs and expiration reflexes were elicited by mechanical stimulation of the intrathoracic trachea or larynx. Augmented breaths occurred spontaneously or were evoked by the same mechanical stimuli. Electromyograms (EMGs) were recorded from the diaphragm, rectus abdominis, and pectoralis major muscles. During augmented breaths, the pectoralis major had inspiratory EMG activity similar to that of the diaphragm, but during expiration reflexes the pectoralis major also had purely expiratory EMG activity similar to the rectus abdominis. During tracheobronchial cough, the pectoralis major had an inspiratory pattern similar to that of the diaphragm in 10 animals, an expiratory pattern similar to that of the rectus abdominis in 3 animals, and a biphasic pattern in 2 animals. The pectoralis major was active during both the inspiratory and expiratory phases during laryngeal cough. We conclude that, in contrast to the diaphragm or rectus abdominis muscles, the pectoralis major is active during both inspiratory and expiratory pulmonary defensive reflexes.
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Affiliation(s)
- D C Bolser
- Department of Physiological Sciences, University of Florida, Gainesville, Florida 32612, USA.
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41
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Bolser DC, DeGennaro FC, O'Reilly S, McLeod RL, Hey JA. Central antitussive activity of the NK1 and NK2 tachykinin receptor antagonists, CP-99,994 and SR 48968, in the guinea-pig and cat. Br J Pharmacol 1997; 121:165-70. [PMID: 9154323 PMCID: PMC1564671 DOI: 10.1038/sj.bjp.0701111] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
1. The purpose of this study was to investigate the antitussive activity and sites of action of the NK1 and NK2 tachykinin receptor antagonists, CP-99,994, SR 48968, and the racemate of SR 48968, SR 48212A in the cat and guinea-pig. 2. Guinea-pigs were dosed subcutaneously (s.c.) with CP-99,994, SR 48212A or SR 48968 one hour before exposure to aerosols of capsaicin (0.3 mM) to elicit coughing. Coughs were detected with a microphone and counted. 3. Intracerebroventricular (i.c.v.) cannulae were placed in the lateral cerebral ventricles of anaesthetized guinea-pigs. Approximately one week later, the animals were dosed with CP-99,994 or SR 48212A (i.c.v.) and exposed to aerosols of capsaicin (0.3 mM) to elicit coughing. 4. Cough was produced in anaesthetized cats by mechanical stimulation of the intrathoracic trachea and was monitored from electromyograms of respiratory muscle activity. Cannulae were placed for intravenous (i.v.) or, in separate groups of animals, intravertebral arterial (i.a.) administration of CP-99,994, SR 48212A or SR 48968. Dose-response relationships for i.v. and i.a. administration of each drug were generated to determine a ratio of i.v. ED50 to i.a. ED50, known as the effective dose ratio (EDR). The EDR will be 20 or greater for a centrally active drug and less than 20 for a peripherally active drug. 5. In the guinea-pig, CP-99,994 (0.1-30 mg kg-1, s.c.), SR 48212A (1.0-30 mg kg-1, s.c.), and SR 48968 (0.3-3.0 mg kg-1, s.c.) inhibited capsaicin-induced cough in a dose-dependent manner. Capsaicin-induced cough was also inhibited by i.c.v. administration of CP-99,994 (10 and 100 micrograms) or SR 48212A (100 micrograms). 6. In the cat, both CP-99,994 (0.0001-0.3 mg kg-1, i.a., n = 5; 0.003-3.0 mg kg-1, i.v., n = 5) and SR 48212A (0.003-1.0 mg kg-1, i.a., n = 5; 0.01-3.0 mg kg-1, i.v., n = 5) inhibited mechanically induced cough by either the i.v. or i.a. routes in a dose-dependent manner. SR 48968 (0.001-0.3 mg kg-1, i.a., n = 5; 0.03-1.0 mg kg-1, i.v., n = 5) inhibited cough when administered by the i.a. route in a dose-dependent manner, but had no effect by the i.v. route up to a dose of 1.0 mg kg-1. Intravenous antitussive potencies (ED50, 95% confidence interval (CI) of these compounds were: CP-99,994 (0.082 mg kg-1, 95% CI 0.047-0.126), SR 48212A (2.3 mg kg-1, 95% CI 0.5-20), and SR 48968 (> 1.0 mg kg-1, 95% CI not determined). The intra-arterial potencies of these compounds were: CP-99,994 (1.0 microgram kg-1, 95% CI 0.4-1.8), SR 48212A (25 micrograms kg-1, 95% CI 13-52), and SR 48968 (8.0 micrograms kg-1, 95% CI 1-32). The derived EDRs for each compound were: CP-99,994, 82; SR 48212A, 92; and SR 48968, > 125. 7. We concluded that CP-99,994 and SR 48968 inhibit cough in the guinea-pig and cat by a central site of action. In the cat, the antitussive action of these compounds appears to be solely by a central site.
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Affiliation(s)
- D C Bolser
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610-0144, USA
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Hey JA, Mingo G, Bolser DC, Kreutner W, Krobatsch D, Chapman RW. Respiratory effects of baclofen and 3-aminopropylphosphinic acid in guinea-pigs. Br J Pharmacol 1995; 114:735-8. [PMID: 7773531 PMCID: PMC1510199 DOI: 10.1111/j.1476-5381.1995.tb13265.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
1. The effects of the GABAB receptor agonists, baclofen and 3-aminopropylphosphinic acid (3-APPi) given by the subcutaneous or intracerebroventricular (i.c.v.) route were examined on minute ventilation (V), tidal volume (VT) and respiratory rate (f) due to room air and carbon dioxide (CO2)-enriched gas hyperventilation in conscious guinea-pigs. 2. Baclofen (0.3-10 mg kg-1, s.c.) produced a dose-dependent inhibition of V and f due to room air and CO2 inhalation. The maximum inhibition of room air breathing V was 85% +/- 3 and f was 74% +/- 3 at 10 mg kg-1, s.c. The maximum effects on CO2-induced hyperventilation were 68% +/- 9 and 51% +/- 6, for V and f respectively. Only the highest dose of baclofen studied (10 mg kg-1) produced a significant inhibition of VT due to room air breathing (46% +/- 6) and CO2 breathing (38% +/- 11). 3. 3-APPi (0.3-100 mg kg-1, s.c.) did not affect V, VT or f due to room air breathing or CO2 inhalation at any dose tested. Also, i.c.v. administration of 3-APPi (100 micrograms) did not affect ventilatory responses due to room air breathing or CO2 inhalation. 4. Pretreatment with the GABAB antagonist, CGP 35348 3-aminopropyl-(diethoxymethyl) phosphinic acid (3-30 mg kg-1, s.c.) blocked the respiratory depressant effects of baclofen (3 mg kg-1, s.c.) in a dose-related fashion. 5. Intracerebroventricular (i.c.v.) administration of CGP 35348 (50 micrograms) blocked the respiratory depressant effects of baclofen. CGP 35348 given alone either i.c.v. or s.c. had no effects on respiration due to room air or CO2 inhalation.6. Pretreatment with either the GABAA antagonist bicuculline (30 mg kg-1, s.c.) or the opioid antagonist, naloxone (1 mg kg-1, s.c.) had no effect on the respiratory depressant action of baclofen(3 mg kg-1, s.c.).7. These results show that baclofen inhibits ventilation due to room air breathing, and attenuates the hyperventilation response to CO2 inhalation. The peripherally acting GABAB agonist, 3-APPi had no effect on ventilation. These findings demonstrate that the respiratory depressant effects of baclofen are due to activation of CNS GABAB receptors and indicates that only GABAB receptor agonists that penetrate into the CNS may cause respiratory depression.
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Affiliation(s)
- J A Hey
- Schering-Plough Research Institute, Kenilworth, NJ 07033-0539, USA
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43
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Abstract
GABAB receptors are a distinct subclass of receptors for the major inhibitory transmitter 4-aminobutanoic acid (GABA) that mediate depression of synaptic transmission and contribute to the inhibition controlling neuronal excitability. The development of specific agonists and antagonists for these receptors has led to a better understanding of their physiology and pharmacology, highlighting their diverse coupling to different intracellular effectors through Gi/G(o) proteins. This review emphasises our current knowledge of the neurophysiology and neurochemistry of GABAB receptors, including their heterogeneity, as well as the therapeutic potential of drugs acting at these sites.
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Affiliation(s)
- D I Kerr
- Department of Anaesthesia and Intensive Care, University of Adelaide, Australia
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44
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Bolser DC, DeGennaro FC, O'Reilly S, Chapman RW, Kreutner W, Egan RW, Hey JA. Peripheral and central sites of action of GABA-B agonists to inhibit the cough reflex in the cat and guinea pig. Br J Pharmacol 1994; 113:1344-8. [PMID: 7889290 PMCID: PMC1510532 DOI: 10.1111/j.1476-5381.1994.tb17145.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
1. The GABA-B receptor agonists baclofen and 3-aminopropylphosphinic acid (3-APPi) have antitussive activity in the cat and guinea pig. The purpose of this study was to investigate the sites of action of these GABA-B receptor agonists to inhibit the cough reflex. 2. Single intracerebroventricular (i.c.v.) cannulas were placed in the lateral ventricles of anaesthetized guinea pigs. Approximately 1 week later, the animals were exposed to aerosols of capsaicin (0.3 mM) to elicit coughing. Coughs were detected with a microphone and counted. 3. Cough was produced in anaesthetized cats by mechanical stimulation of the intrathoracic trachea and was recorded from electromyograms of respiratory muscle activity. Cannulas were placed for intravenous (i.v.) or, in separate groups of animals, intravertebral arterial (i.a.) administration of baclofen, 3-APPi, the centrally active antitussive drug codeine or the peripherally active antitussive drug BW443c. Dose-response relationships for i.v. and i.a. administration of each drug were generated to determine a ratio of i.v. ED50 to i.a. ED50, known as the effective dose ratio (EDR). The EDR will be 20 or greater for a centrally acting drug. 4. In the guinea pig, baclofen (3 mg kg-1, s.c.) and 3-APPi (10 mg kg-1, s.c.) inhibited capsaicin-induced cough by 50% and 35% respectively. The antitussive activity of baclofen was completely blocked by i.c.v. administration of the GABA-B receptor antagonist CGP 35348 (10 micrograms). Conversely, the antitussive effect of 3-APPi was unaffected by i.c.v. CGP 35348. However, systemic administration of CGP 35348 (30 mg kg-1, s.c.) completely blocked the antitussive activity of 3-APPi (10 mg kg-1, s.c.). In separate experiments baclofen alone (1 microg, i.c.v.) inhibited capsaicin-induced cough by 78%. 3-APPi (10 and 100 microg, i.c.v.) had no effect on capsaicin-induced cough in the guinea pig.5. In the cat, potencies (ED50) of the standards and GABA-B agonists by the i.v. route were: codeine(0.34 mg kg-1), BW443C (0.17 mg kg-1), baclofen (0.63 mg kg-1) and 3-APPi (2.3 mg kg-1). Potencies of these drugs by the i.a. route were: codeine, 0.013 mg kg-1; BW443C, 0.06mg kg-1; baclofen,0.016mg kg-1; and 3-APPi, 0.87 mg kg-1. The EDRs for each drug were: codeine, 26; BW443C, 3;baclofen, 39; and 3-APPi, 3.6 We conclude that in both the cat and guinea pig baclofen inhibits cough by a central site of action,while 3-APPi inhibits cough by a peripheral site of action.
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Affiliation(s)
- D C Bolser
- Schering-Plough Research Institute, Kenilworth, NJ 07033
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