EFFECTS OF METHANOL LEAF EXTRACT OF MORINGA OLEIFERA ON NEUROBEHAVIOURAL AND OXIDATIVE STRESS CHANGES INDUCED BY SUBCHRONIC EXPOSURE TO CHLORPYRIFOS IN MALE WISTAR RATS

•                  TABLE OF CONTENTS Declaration....................................................................................................................... iii Certification ..................................................................................................................... iv Dedication......................................................................................................................... v Acknowledgments ........................................................................................................... vi Abstract........................................................................................................................... vii Table of Contents............................................................................................................. ix List of Tables................................................................................................................. xiv List of Figures................................................................................................................. xv List of Plates ................................................................................................................. xvii List of Abbreviations................................................................................................... xviii 

Chapter ONE

INTRODUCTION

• ........................................................................... 1 
• 1.1Background ......................................................................................................... 1 
• 1.2Statement of Research Problem ........................................................................ 3 
• 1.3Justification ......................................................................................................... 5 
• 1.4General Aim of the Study................................................................................... 6 
• 1.5Objectives of the Study....................................................................................... 6 
• 1.6Research Hypothesis (H0)................................................................................... 7 

Chapter TWO

LITERATURE REVIEW

• .............................................................. 8 
• 2.1Pesticides.............................................................................................................. 8 2.
• 1.1Classification of pesticides ................................................................................... 8 
• 2.2Organophosphates.............................................................................................. 9 2.
• 2.1Classification of organophosphates...................................................................... 9 2.
• 2.2History of organophosphates.............................................................................. 10 2.
• 2.3Uses of organophosphates .................................................................................. 11 2.
• 2.4Mechanism of action of organophosphates ........................................................ 12 2.
• 2.5Organophosphate toxicity................................................................................... 13 
• 2.3Chlorpyrifos ...................................................................................................... 19 2.
• 3.1Pharmacodynamics of chlorpyrifos.................................................................... 20 2.
• 3.2Pharmacokinetics of chlorpyrifos....................................................................... 20 2.
• 3.3Chlorpyrifos toxicity........................................................................................... 22 
• 2.4Formation and Action of Reactive Oxygen Species....................................... 29 2.
• 4.1Effects of free radicals on biological systems .................................................... 31 
• 2.5Antioxidants and their Defence System.......................................................... 33 2.
• 5.1Antioxidants........................................................................................................ 33 2.
• 5.2Antioxidant defence system................................................................................ 35 
• 2.6Oxidative Stress - a Mechanism of Chlorpyrifos Toxicity ............................ 36 
• 2.7Moringa oleifera ................................................................................................ 38 2.
• 7.1Moringa oleifera: description ............................................................................. 38 2.
• 7.2Nutritional properties and ethnomedical uses of Moringa oleifera.................... 39 2.
• 7.3Antioxidant properties of Moringa oleifera........................................................ 40 

Chapter THREE

RESEARCH METHODOLOGY

• MATERIALS AND METHODS ............................................ 42 
• 3.1Plant Materials.................................................................................................. 42 3.
• 1.1Plant collection, identification, extraction and preparation ................................ 42 3.
• 1.2Phytochemical screening of leaf extract ............................................................. 42 3.
• 1.3Quantitative analysis of methanol extract of Moringa oleifera leaf for flavonoids and antioxidant vitamins..................................................................................... 43 
• 3.2Chemical Acquisition and Preparation .......................................................... 43 
• 3.3LD50 Determination .......................................................................................... 43 
• 3.4Experimental Animals...................................................................................... 44 
• 3.5Experimental Groupings/Treatments............................................................. 44 
• 3.6Evaluation of neurobehavioural and cognitive changes................................ 45 3.
• 6.1Open-field assessment ........................................................................................ 45 3.
• 6.2Assessment of neuromuscular coordination …………………………………….…...46 3.
• 6.3Assessment of motor coordination ..................................................................... 46 3.
• 6.4Assessment of locomotor efficiency................................................................... 47 3.
• 6.5Assessment of motor strength............................................................................. 47 3.
• 6.6Assessment of excitability score......................................................................... 47 3.
• 6.7Assessment of depression ................................................................................... 48 3.
• 6.8Evaluation of learning and short-term memory.................................................. 48 
• 3.7Preparation of Brain Samples ......................................................................... 49 
• 3.8Assessment of Acetylcholinesterase Activity .................................................. 49 
• 3.9Assessment of Brain Lipoperoxidation........................................................... 50 
• 3.10Assessment of Brain Antioxidant Enzyme Activities .................................... 50 
• 3.11Histopathology .................................................................................................. 51 
• 3.12Data Analysis..................................................................................................... 52 

Chapter FOUR

DATA PRESENTATION AND ANALYSIS

• RESULTS.................................................................................... 53 
• 4.1Determination of Median Lethal Dose............................................................ 53 4.
• 1.1Determination of median lethal dose for chlorpyrifos........................................ 53 4.
• 1.2Determination of median lethal dose for Moringa oleifera leaf extract............. 55 
• 4.2Moringa oleifera Leaf: Methanol Extract Characteristics............................ 55 4.
• 2.1Methanol extract yield of moringa oleifera leaf................................................. 55 4.
• 2.2Phytochemical components of methanol extracts of Moringa oleifera leaf....... 55 4.
• 2.3Flavonoid and antioxidant vitamin contents of Moringa oleifera leaf extract ... 57 
• 4.3Subchronic Toxicity Study............................................................................... 59 4.
• 3.1Clinical signs....................................................................................................... 59 
• 4.4Effect of Treatments on Neurobehaviour....................................................... 59 4.
• 4.1Effect of treatments on open-field performance ................................................. 59 4.
• 4.2Effect of treatments on beam-walk score ........................................................... 75 4.
• 4.3Effect of treatments on ladder-walk performance .............................................. 77 4.
• 4.4Effect of treatments on inclined plane performance........................................... 80 4.
• 4.5Effect of treatments on forepaw grip time .......................................................... 82 4.
• 4.6Effect of treatments on excitability scores.......................................................... 85 4.
• 4.7Effect of treatments on forced swimming test.................................................... 88 4.
• 4.8Effect of treatments on learning acqusition ........................................................ 91 4.
• 4.9Effect of treatments on short-term memory........................................................ 91 
• 4.5Effect of Treatments on Brain Acetylcholinesterase Activity....................... 94 
• 4.6Effect of Treatments on Brain Malondialdehyde Concentration................. 94 
• 4.7Effect of Treatments on Brain Antioxidant Enzymes ................................... 97 4.
• 7.1Effect of treatments on brain superoxide dismutase activity.............................. 97 4.
• 7.2Effect of treatments on brain glutathione peroxidase activity ............................ 97 4.
• 7.3Effect of treatments on brain catalase activity.................................................... 97 
• 4.8Effect of Treatments on Brain Histo-architecture....................................... 102 

Chapter FIVE

SUMMARY, CONCLUSION AND RECOMMENDATIONS

• DISCUSSION ............................................................................. 109 CHAPTER SIX: CONCLUSION AND RECOMMENDATIONS ........................ 130 
• 6.1Conclusion ....................................................................................................... 130 6.
• 2.Recommendations........................................................................................... 130 6.
• 2.1Specific recommendations................................................................................ 130 6.
• 2.2General recommendations ................................................................................ 131 REFERENCES…………………………………………………………………………….……… 132