ANTINOCICEPTIVE ACTIVITIES OF EXTRACTS OF CROTON MEGALOCARPUS HUTCH (Eurphobiaceae) USING ANIMAL MODELS WILLIAM GITAU GICHUI BPharm H56/83352/2012 THESIS SUBMITTED IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF SCIENCE IN MEDICAL PHYSIOLOGY, UNIVERSITY OF NAIROBI, KENYA 2016 I This thesis has been submitted for examination with our approval as university supervisors. “igatue ………………………………………………..date --------------------------- Dr. Hellen N. Kariuki, BDS, MSc., PhD Department of Medical Physiology University of Nairobi “igatue ………………………………………………..date --------------------------- Dr. Frank Waweru, MBchB, MSc. Department of medical physiology University of Nairobi II Table of Contents Table of Tables.......................................................................................................................................... v Table of Figures ........................................................................................................................................ v Table of Appendices ................................................................................................................................. v Abbreviations .............................................................................................................................................. vi DECLARATION ............................................................................................................................................. vii ACKNOWLEDGEMENT ............................................................................................................................... viii DEDICATION.................................................................................................................................................. x ABSTRACT .................................................................................................................................................... xi CHAPTER ONE ............................................................................................................................................... 1 1. INTRODUCTION AND LITERATURE REVIEW ......................................................................................... 1 1.1 Croton megalocarpus ...................................................................................................................... 1 1.2. Pain .................................................................................................................................................... 5 1.2.1. Problem of Pain ........................................................................................................................... 5 1.2.2. Nociception ................................................................................................................................. 6 1.2.3. Pain Management ..................................................................................................................... 11 1.2.4. Nociceptive Tests ...................................................................................................................... 13 1.3.1. Statement of the Research Problem ......................................................................................... 16 1.3.2. Justification ............................................................................................................................... 16 1.4. OBJECTIVES OF THE STUDY ................................................................................................................. 16 1.4.1. Overall Objective .......................................................................................................................... 16 1.4.2. Specific Objective ......................................................................................................................... 16 1.4.3. Null Hypothesis ............................................................................................................................ 16 CHAPTER TWO ............................................................................................................................................ 17 2.0. MATERIALS AND METHODS ............................................................................................................ 17 2.1. Materials ...................................................................................................................................... 17 2.2. Drugs and Chemicals .................................................................................................................... 17 2.3. Experimental Animals .................................................................................................................. 17 2.4. Experimental Design .................................................................................................................... 18 2.5. Extraction ..................................................................................................................................... 18 2.6. Drug Administration ..................................................................................................................... 18 2.7. Sensorimotor Test ........................................................................................................................ 19 2.8. Nociceptive tests .......................................................................................................................... 19 III 2.9. STATISTICAL ANALYSIS ................................................................................................................. 21 CHAPTER 3 .................................................................................................................................................. 22 3. RESULTS, DISCUSSION AND CONCLUSION......................................................................................... 22 3.1. Writhing test ................................................................................................................................ 22 3.2. Tail Flick Test ................................................................................................................................ 23 3.3. Formalin Test. .............................................................................................................................. 24 3.4. DISCUSSION ..................................................................................................................................... 26 3.5. CONCLUSION ................................................................................................................................... 28 3.6. RECOMMENDATIONS ...................................................................................................................... 28 3.6. LIMITATIONS OF STUDY .................................................................................................................. 28 4. REFERENCES ............................................................................................................................................ 29 IV Table of Tables Table 1: Effect of C. megalocarpus on Writhing Test .......................................................... 222 Table 2: Effect of C. megalocarpus extract on Tail Flicking Time in mice ........................... 244 Table 3: Effect of C. megalocarpus extract on the Formalin Test ....................................... 255 Table of Figures Figure 1: Effect of C. megalocarpus on percentage inhibition on Writhing Test ................ 233 Figure 2: Effect of C. megalocarpus extracts on Tail Flicking Time in mice......................... 244 Figure 3: Effect of C. megalocarpus extract on the Early Phase of Formalin test ............... 266 Table of Appendices APPENDIX 1................................................................................................................................. 399 Writhing Test Raw Data .......................................................................................................... 399 APPENDIX 2................................................................................................................................. 411 Tail Flick Test Raw Data ........................................................................................................... 411 APPENDIX 3................................................................................................................................. 433 Formalin Test Raw Data .......................................................................................................... 433 APPENDIX 4................................................................................................................................. 455 Croton megalocarpus Images .................................................................................................. 455 V Abbreviations 5HT2 receptors: 5-Hydroxytrptamine 2 Receptors ANOVA: Analysis of Variance CNS: Central Nervous System COX Enzyme: Cyclooxygenase Enzyme CME: Croton megalocarpus Extract DMSO: Dimethyl Sulphoxide IASP: International Association for the Study of Pain LOX: Lipoxygenase Enzyme NDHN: Nociceptive Dorsal Horn Neurons NIH: National Center for Health Statistics NSAID: Nonsteroidal Anti-inflammatory Drug PG: Prostaglandin PG E2: Prostaglandin E2 PGFα: Prostaglandin Fα SEM: Standard Error of Mean WHO: World Health Organization VI DECLARATION The thesis is my original work and has not been submitted for a degree in any other university. “igatue