<p>&nbsp;                <b>TABLE OF CONTENTS&nbsp;</b></p><p>Declaration....................................................................................................................... iii&nbsp;</p><p>Certification ..................................................................................................................... iv&nbsp;</p><p>Dedication......................................................................................................................... v&nbsp;</p><p>Acknowledgments ........................................................................................................... vi&nbsp;</p><p>Abstract........................................................................................................................... vii&nbsp;</p><p>Table of Contents............................................................................................................. ix&nbsp;</p><p>List of Tables................................................................................................................. xiv&nbsp;</p><p>List of Figures................................................................................................................. xv&nbsp;</p><p>List of Plates ................................................................................................................. xvii&nbsp;</p><p>List of Abbreviations................................................................................................... xviii&nbsp;</p><p>

Chapter ONE

: INTRODUCTION........................................................................... 1&nbsp;</p><p>1.1 Background ......................................................................................................... 1&nbsp;</p><p>1.2 Statement of Research Problem ........................................................................ 3&nbsp;</p><p>1.3 Justification ......................................................................................................... 5&nbsp;</p><p>1.4 General Aim of the Study................................................................................... 6&nbsp;</p><p>1.5 Objectives of the Study....................................................................................... 6&nbsp;</p><p>1.6 Research Hypothesis (H0)................................................................................... 7&nbsp;</p><p>

Chapter TWO

: LITERATURE REVIEW.............................................................. 8&nbsp;</p><p>2.1 Pesticides.............................................................................................................. 8&nbsp;</p><p>2.1.1 Classification of pesticides ................................................................................... 8&nbsp;</p><p>2.2 Organophosphates.............................................................................................. 9&nbsp;</p><p>2.2.1 Classification of organophosphates...................................................................... 9&nbsp;</p><p>2.2.2 History of organophosphates.............................................................................. 10&nbsp;</p><p>2.2.3 Uses of organophosphates .................................................................................. 11&nbsp;</p><p>2.2.4 Mechanism of action of organophosphates ........................................................ 12&nbsp;</p><p>2.2.5 Organophosphate toxicity................................................................................... 13&nbsp;</p><p>2.3 Chlorpyrifos ...................................................................................................... 19&nbsp;</p><p>2.3.1 Pharmacodynamics of chlorpyrifos.................................................................... 20&nbsp;</p><p>2.3.2 Pharmacokinetics of chlorpyrifos....................................................................... 20&nbsp;</p><p>2.3.3 Chlorpyrifos toxicity........................................................................................... 22&nbsp;</p><p>2.4 Formation and Action of Reactive Oxygen Species....................................... 29&nbsp;</p><p>2.4.1 Effects of free radicals on biological systems .................................................... 31&nbsp;</p><p>2.5 Antioxidants and their Defence System.......................................................... 33&nbsp;</p><p>2.5.1 Antioxidants........................................................................................................ 33&nbsp;</p><p>2.5.2 Antioxidant defence system................................................................................ 35&nbsp;</p><p>2.6 Oxidative Stress - a Mechanism of Chlorpyrifos Toxicity ............................ 36&nbsp;</p><p>2.7 Moringa oleifera ................................................................................................ 38&nbsp;</p><p>2.7.1 Moringa oleifera: description ............................................................................. 38&nbsp;</p><p>2.7.2 Nutritional properties and ethnomedical uses of Moringa oleifera.................... 39&nbsp;</p><p>2.7.3 Antioxidant properties of Moringa oleifera........................................................ 40&nbsp;</p><p>

Chapter THREE

: MATERIALS AND METHODS ............................................ 42&nbsp;</p><p>3.1 Plant Materials.................................................................................................. 42&nbsp;</p><p>3.1.1 Plant collection, identification, extraction and preparation ................................ 42&nbsp;</p><p>3.1.2 Phytochemical screening of leaf extract ............................................................. 42&nbsp;</p><p>3.1.3 Quantitative analysis of methanol extract of Moringa oleifera leaf for flavonoids and antioxidant vitamins..................................................................................... 43&nbsp;</p><p>3.2 Chemical Acquisition and Preparation .......................................................... 43&nbsp;</p><p>3.3 LD50 Determination .......................................................................................... 43&nbsp;</p><p>3.4 Experimental Animals...................................................................................... 44&nbsp;</p><p>3.5 Experimental Groupings/Treatments............................................................. 44&nbsp;</p><p>3.6 Evaluation of neurobehavioural and cognitive changes................................ 45&nbsp;</p><p>3.6.1 Open-field assessment ........................................................................................ 45&nbsp;</p><p>3.6.2 Assessment of neuromuscular coordination …………………………………….…...46&nbsp;</p><p>3.6.3 Assessment of motor coordination ..................................................................... 46&nbsp;</p><p>3.6.4 Assessment of locomotor efficiency................................................................... 47&nbsp;</p><p>3.6.5 Assessment of motor strength............................................................................. 47&nbsp;</p><p>3.6.6 Assessment of excitability score......................................................................... 47&nbsp;</p><p>3.6.7 Assessment of depression ................................................................................... 48&nbsp;</p><p>3.6.8 Evaluation of learning and short-term memory.................................................. 48&nbsp;</p><p>3.7 Preparation of Brain Samples ......................................................................... 49&nbsp;</p><p>3.8 Assessment of Acetylcholinesterase Activity .................................................. 49&nbsp;</p><p>3.9 Assessment of Brain Lipoperoxidation........................................................... 50&nbsp;</p><p>3.10 Assessment of Brain Antioxidant Enzyme Activities .................................... 50&nbsp;</p><p>3.11 Histopathology .................................................................................................. 51&nbsp;</p><p>3.12 Data Analysis..................................................................................................... 52&nbsp;</p><p>

Chapter FOUR

: RESULTS.................................................................................... 53&nbsp;</p><p>4.1 Determination of Median Lethal Dose............................................................ 53&nbsp;</p><p>4.1.1 Determination of median lethal dose for chlorpyrifos........................................ 53&nbsp;</p><p>4.1.2 Determination of median lethal dose for Moringa oleifera leaf extract............. 55&nbsp;</p><p>4.2 Moringa oleifera Leaf: Methanol Extract Characteristics............................ 55&nbsp;</p><p>4.2.1 Methanol extract yield of moringa oleifera leaf................................................. 55&nbsp;</p><p>4.2.2 Phytochemical components of methanol extracts of Moringa oleifera leaf....... 55&nbsp;</p><p>4.2.3 Flavonoid and antioxidant vitamin contents of Moringa oleifera leaf extract ... 57&nbsp;</p><p>4.3 Subchronic Toxicity Study............................................................................... 59&nbsp;</p><p>4.3.1 Clinical signs....................................................................................................... 59&nbsp;</p><p>4.4 Effect of Treatments on Neurobehaviour....................................................... 59&nbsp;</p><p>4.4.1 Effect of treatments on open-field performance ................................................. 59&nbsp;</p><p>4.4.2 Effect of treatments on beam-walk score ........................................................... 75&nbsp;</p><p>4.4.3 Effect of treatments on ladder-walk performance .............................................. 77&nbsp;</p><p>4.4.4 Effect of treatments on inclined plane performance........................................... 80&nbsp;</p><p>4.4.5 Effect of treatments on forepaw grip time .......................................................... 82&nbsp;</p><p>4.4.6 Effect of treatments on excitability scores.......................................................... 85&nbsp;</p><p>4.4.7 Effect of treatments on forced swimming test.................................................... 88&nbsp;</p><p>4.4.8 Effect of treatments on learning acqusition ........................................................ 91&nbsp;</p><p>4.4.9 Effect of treatments on short-term memory........................................................ 91&nbsp;</p><p>4.5 Effect of Treatments on Brain Acetylcholinesterase Activity....................... 94&nbsp;</p><p>4.6 Effect of Treatments on Brain Malondialdehyde Concentration................. 94&nbsp;</p><p>4.7 Effect of Treatments on Brain Antioxidant Enzymes ................................... 97&nbsp;</p><p>4.7.1 Effect of treatments on brain superoxide dismutase activity.............................. 97&nbsp;</p><p>4.7.2 Effect of treatments on brain glutathione peroxidase activity ............................ 97&nbsp;</p><p>4.7.3 Effect of treatments on brain catalase activity.................................................... 97&nbsp;</p><p>4.8 Effect of Treatments on Brain Histo-architecture....................................... 102&nbsp;</p><p>

Chapter FIVE

: DISCUSSION ............................................................................. 109&nbsp;</p><p>CHAPTER SIX: CONCLUSION AND RECOMMENDATIONS ........................ 130&nbsp;</p><p>6.1 Conclusion ....................................................................................................... 130&nbsp;</p><p>6.2. Recommendations........................................................................................... 130&nbsp;</p><p>6.2.1 Specific recommendations................................................................................ 130&nbsp;</p><p>6.2.2 General recommendations ................................................................................ 131&nbsp;</p><p>REFERENCES…………………………………………………………………………….……… 132 <br></p>