Investigation Into the Effects of Specific Muscarinic Acetylcholine Receptor
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Investigation into the effects of specific muscarinic acetylcholine receptor antagonists on the myocardium in pre- clinical conditions of ischaemia reperfusion injury and oxidative stress model Khan, J. Submitted version deposited in CURVE March 2016 Original citation: Khan, J. (2015) Investigation into the effects of specific muscarinic acetylcholine receptor antagonists on the myocardium in pre-clinical conditions of ischaemia reperfusion injury and oxidative stress model. Unpublished PhD Thesis. Coventry: Coventry University Copyright © and Moral Rights are retained by the author. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. This item cannot be reproduced or quoted extensively from without first obtaining permission in writing from the copyright holder(s). The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the copyright holders. Some materials have been removed from this thesis due to third party copyright. Pages where material has been removed are clearly marked in the electronic version. The unabridged version of the thesis can be viewed at the Lanchester Library, Coventry University. CURVE is the Institutional Repository for Coventry University http://curve.coventry.ac.uk/open Investigation into the effects of specific muscarinic acetylcholine receptor antagonists on the myocardium in pre-clinical conditions of ischaemia reperfusion injury and oxidative stress model By Jawad Ahmed Khan November 2015 A thesis submitted in partial fulfilment of the University’s requirements for the Degree of Doctor of Philosophy 1 Acknowledgements I would like to express my deepest appreciation to my supervisors; Prof. Helen Maddock and Dr. Afthab Hussain for giving me the opportunity to undertake this project and also for their continuous support throughout my PhD. I would also like to thank Coventry University and Brookes Pharmaceuticals for funding my PhD. In addition, I would also like to thank the lab technician, Mark Bodycote for his support and patience throughout the period of my PhD. Furthermore, I would like to express my gratitude to my friends and lab colleagues Aaron Nagra, Maryam Babba and Mayel Gharanea for their support and friendship. Most importantly, I am indebted to my parents, my wife and her parents for their continuous encouragement, love and support at all times throughout my PhD. I am very privileged to have such a loving and caring family around me as without their assistance, completing my PhD would not have been possible. 2 Abstract Muscarinic acetylcholine receptors (mAChRs) are G-protein coupled receptors that mediate various actions of Acetylcholine (ACh) in the central nervous system and peripheral nervous system. In mammals, five distinct mAChR subtypes (M1-M5) have been recognised with the M2 subtype being predominantly present in the heart. The mAChR antagonists are routinely used for the treatment of various pathophysiological conditions including respiratory conditions. However, it has been postulated that mAChR antagonists may increase morbidity and mortality in chronic obstructive pulmonary disorder (COPD) and asthma patients with underlying cardiovascular disease, raising concerns regarding the cardiovascular safety of these agents. The current study was therefore undertaken to investigate the effects of individual mAChR antagonists in the setting of myocardial ischaemia reperfusion injury and oxidative stress models. We also investigated whether the inhibition of the mitochondrial permeability transition pore (MPTP) with cyclosporine-A (CsA) in the presence and absence of individual mAChR antagonists provided protection against ischaemia reperfusion injury. Furthermore, we also aimed to investigate the intracellular signalling pathway associated with mAChRs antagonists mediated myocardial injury under the stress conditions. Langendorff results showed that the non-selective M1-M3 mAChR antagonist, ipratropium bromide, the M2 mAChR antagonist, AF-DX 116 and the M3 mAChR antagonist, DAU 5884 significantly increased the infarct size to risk ratio of the heart in conditions of ischaemia and reperfusion. Detrimental effects of AF-DX 116 and DAU 5884 were abrogated by co-treatment of these drugs with mAChR agonist, acetylcholine (ACh) and/or CsA. Cell viability data of isolated cardiac myocytes revealed that AF-DX 116 and DAU 5884 caused a concentration 3 dependent decrease in the viability of cardiac myocytes as well as causing a reduction in the time taken to depolarisation and hypercontracture under oxidative stress. AF-DX 116 and DAU 5884 significantly increased the levels of p-SAPK/JNK and decreased the levels of p-Akt and p-ERK. In addition, ACh and CsA showed to activate p-Akt and p-ERK. To conclude, the data suggest that AF-DX 116 and DAU 5884 caused cardiotoxicity at cellular, tissue and protein level in conditions of ischaemia reperfusion injury and oxidative stress. Furthermore, inhibition of the mitochondrial transition pore with CsA protected against the AF- DX 116 and DAU 5884 induced injury via activation of the pro-survival proteins, p-Akt and p- ERK. 4 Contents Page Acknowledgement………………………………………………………………………………2 Abstract……………………………………………………………………….............................3 Table of contents………………………………………………………………………………...5 List of figures……………………………………………………………………………………12 List of tables…………………………………………………………………………………......19 Abbreviations……………………………………………………………………………………22 Chapter One: General Introduction…………………………………………………………..26 1.1 Chronic Obstructive Pulmonary Disease………………………………………………..26 1.1.2 COPD treatment………………………………………………………............................28 1.1.3 Side effects associated with ipratropium and tiotropium………………………………...31 1.2 Coronary heart disease…………………………………………………………………...31 1.2.1 Oxygen derived free radicals…………………………………………………………….33 1.2.2 Calcium overload………………………………………………………………………...34 1.2.3 Apoptosis………………………………………………………………………………...37 1.2.4 Necrosis…………………………………………………………………………………..42 1.2.5 Autophagy…………………………………......................................................................43 1.3 Myocardial injury signalling pathway…………………………………………………...44 1.3.1 Mitogen activated protein kinase………………………………………………………...44 1.3.2 Phosphatidylinositol-3-Kinase.…………………………………………………………..46 1.3.3 G protein coupled receptors……………………………………………………………...48 1.4 Muscarinic receptors……………………………………………………………………..49 1.4.1 M1 receptors……………………………………………………………………………...50 1.4.2 M2 receptors……………………………………………………………………………...51 1.4.3 M3 receptors……………………………………………………………………………...51 1.4.4 Adenylyl cyclase…………………………………………………………………………52 1.4.5 Phospholipase C………………………………………………………………………….54 1.5 Acetylcholine…………………………………………………………………………….55 5 1.5.1 Clinical relevance of mAChRs…………………………………………………………..57 1.5.2 Alzheimer’s disease and cognitive impairments…………………………………………57 1.5.3 Overactive bladder…………………………………………………………………….....58 1.5.4 Irritable bowel syndrome…………………………………………………………….......60 1.6 Mitochondrial permeability transition pore……………………………………………...56 1.7 Biomarkers of myocardial injury………………………………………………………...62 1.7.1 Clinical cardiac biomarkers……………………………………………………………...63 1.7.2 Micro RNA……………………………………………………………………………....64 1.7.3 miRNAs as biomarkers…………………………………………………………………..65 Hypotheses……………………………………………………………………………………….67 Chapter Two: Methods…………………………………………………………………………68 2.1.1 Animals………………………………………………………………………………….68 2.1.2 Materials………………………………………………………………………………...68 2.2 Isolated perfused heart preparation………………………………………………………69 2.3.1 Isolation of cardiac myocyte…………………………………………………………......72 2.3.2 MTT assay……………………………………………………………………………….73 2.4 MPTP oxidative stress model protocol……………………………………………….....74 2.5 Western blot…………………………………………………………………..................75 2.5.1 Tissue preparation…………………………………………………………………….....75 2.5.2 Gel electrophoresis………………………………………………………………………76 2.5.3 Transfer………………………………………………………………………………….76 2.5.4 Antibody incubation…………………………………………………………………......77 2.5.5 Detection of proteins…………………………………………………………………….77 2.6 miRNA analysis…………………………………………………………………………77 2.7.1 Statistical analysis………………………………………………………………………..78 2.7.2 miRNA data calculation and analysis……………………………………………………79 6 Chapter Three: Investigation into the effects of Ipratropium bromide and Telenzepine dihydrochloride on heart undergoing ischaemia reperfusion injury and cardiac myocytes undergoing oxidative stress…………….................................................................................80 3.1 Introduction……………………………………………………………………………80 3.2 Methods……………………………………………………………………………......81 3.2.1 Isolated perfused heart preparation……………………………………………….........81 3.2.2 Langendorff protocol…………………………………………………………………..81 3.2.3 MTT analysis of cell viability…………………………………………………….........82 3.2.4 Statistical analysis……………………………………………………………………....82 3.3 Results………………………………………………………………………………….83 3.3.1 The effects of ipratropium bromide on the infarct size from the Langendorff experiments under normoxic conditions……………………………………………………………..83 3.3.2 The effects of ipratropium bromide on the infarct size from the Langendorff experiments undergoing ischaemia reperfusion injury……………………………………………....83 3.3.3 The effects of ipratropium bromide on the viability of isolated cardiac myoctes under normoxic conditions……………………………………………………………………85 3.3.4 The effects of ipratropium bromide on the viability of isolated cardiac myoctes under hypoxia and re-oxygenation……………………………………………………………86