Neuroprotective Potential of Lantana Trifolium Ethanolic Extract Against Ethambutol Induced Changes in the Optic Nerve

ABSTRACT Introduction: Ethambutol (EMB) has been discovered as an anti-tuberculosis drug since 1960, and is now very important in treatment of multidrug resistant tuberculosis which is on a rise due to emergence of Human Immunodeficiency Virus. However, EMB has been associated with severe side effects including optic neuropathy with no preventive and treatment measures. Purpose: To establish the protective potential of Lantana trifolium ethanolic extract against EMB induced optic nerve changes. Materials and Methods: Experimental design involving 25 male adult Wistar rats of 110-130g average weight, divided into five groups each comprising five animals. All rats were fed on standard commercial rat pellets and water ad libitum for five weeks. Group A, the negative control received distilled water. Group B, the positive control was treated with EMB 100 mg/kg/day. Test groups C, D, and E were treated with 25, 50, and 100 mg/kg/day of trifolium Extract (TE) respectively, one hour before administering 100 mg/kg/day of EMB. Visual acuity during the 15 3rd, and 5th week was determined by the mean escape latencies obtained using a modified Moris water maze. Optic nerves were macroscopically examined for gross morphological changes. The optic nerves were excised, processed and stained using Luxol fast blue, Hematoxlyin and Eosin for histological studies. A light microscope (x40) was used to examine optic nerve histological changes and ImageJ for analysis. Results and Discussion: Lantana trifolium ethanolic extract had a dose dependent protective potential against EMB induced changes. This was shown by the significant difference in visual acuity during the 5th week. There was a significant increase in the escape latenc,ies of positive control group (9.65±1.22) when compared with those of the negative control group (4.35±0.50), EMB +50mg/kg TE group (4.85±0.65), and EMB + l00mg/kg TE group (3.6±0.38). The neuroprotective effect was further shown by the significant difference in histological changes. The protective potential of Latana trifolium is likely due to the anti-oxidative and antiinflammatory activities. Conclusion and Recommendation: Lantana trifolium ethanolic extract has a dose dependent neuroprotective potential against EMB induced changes in the optic nerve. Since the exact phytochemical component and mechanism of action responsible for this effect are not known, further studies to find this out are strongly recommended. Key Words: Ethambutol, Optic Nerve, Lantana trifolium, Optic Neuropathy.

 TABLE OF CONTENTS 

DECLARATION .......................................................................................................................................... ii 

SUPERVISORS APPROVAL ..................................................................................................................... iii 

DEDICATION ............................................................................................................................................. iv 

ACKNOWLEDGMENT ............................................................................................................................... v 

LIST OF FIGURES ................................................................................................................................... viii 

LIST OF TABLES ..................................................................................................................................... viii 

LIST OF ABBREVIATIONS ...................................................................................................................... ix 

ABSTRACT .................................................................................................................................................. x 

CHAPTER ONE ........................................................................................................................................... 1 

INTRODUCTION ........................................................................................................................................ 1 

1.1 Background to the study ..................................................................................................................... I 

1.2 Problem Statement .............................................................................................................................. 2 

1.3 Purpose of the Study ........................................................................................................................... 3 

1.4 Specific Objectives ............................................................................................................................. 3 

1.5 Research Hypothesis ........................................................................................................................... 3 

1.6 Scope of Study .................................................................................................................................... 3 

1.7 Justification ......................................................................................................................................... 4 

1.8 Conceptual Framework ....................................................................................................................... 4 

CHAPTER TWO .......................................................................................................................................... 5 

LITERATURE REVIEW ............................................................................................................................. 5 

2.1 Visual acuity ....................................................................................................................................... 5 

2.2 Optic Nerve ......................................................................................................................................... 6 

2.3 Ethambutol Induced Optic Neuropathy .............................................................................................. 9 

2.4 Lantana trifoliwn .............................................................................................................................. 12 

CHAPTER THREE .................................................................................................................................... 14 

RESEARCH METHODOLOGY ................................................................................................................ 14 

3.1 Study Design ..................................................................................................................................... 14 

3.2 Study Population ............................................................................................................................... 14 

3.3 Sample Size ....................................................................................................................................... 14 

3.4 Preparation of the Extract ................................................................................................................. 14 

3.4.1 Plant ........................................................................................................................................... 14 

3.4.2. Preparation and Storage of the Extract. ..................................................................................... 15 

3.5 Animal Studies .................................................................................................................................. 15 

3.5.1 Experimental Animals ................................................................................................................ 15 

3.5.2 Animal Grouping ....................................................................................................................... 15 

3.5.3 Administration ofEthambutol and Lantana trifolium Ethanolic Extract. .................................. 16 

3.6 Data Collection Technique ................................................................................................................ 16 

3.6.1 Visual Acuity Testing ................................................................................................................ 16 

3.6.2 Gross Morphological and Histological Analysis of the Optic Nerve ......................................... 17 

3. 7 Data Analysis and Presentation ......................................................................................................... 19 

3.9 Limitations and Delimitations ........................................................................................................... 19 

3.8 Ethical Considerations ...................................................................................................................... 20 

CHAPTER FOUR ....................................................................................................................................... 21 

PRESENTATION AND INTERPRETATION OF RESULTS .................................................................. 21 

4.1 Effect of Lantana tr{folium Ethanolic Extract on Ethambutol Induced Changes in Visual Acuity .. 21 

4.2 Effect of Lantana tr{folium Ethanolic Extract on Ethambutol Induced Changes on the Gross 

Mo1phology of the Optic Nerve .............................................................................................................. 22 

4.3 Effect of Lantana trifolium Ethanolic Extract on Ethambutol Induced Changes in the Histology of 

the Optic Nerve ....................................................................................................................................... 23 

CHAPTER FIVE ........................................................................................................................................ 27 

DISCUSSION, CONCLUSIONS AND RECOMMENDATIONS ............................................................ 27 

5.1 DJSCUSSJON ....................................................................................................................................... 27 

5.1.1 Effect of Lantana trifoliwn Ethanolic Extract on Ethambutol Induced Changes in Visual Acuity27 

5.1.2 Effect of Lantana trifolium Ethanolic Extract on Ethambutol Induced Changes on the Gross 

Morphology of the Optic Nerve .............................................................................................................. 28 

5.1.3 Effect of Lantana trifolium Extract on Ethambutol Induced Changes in the Histology of the Optic 

Nerve ....................................................................................................................................................... 28 

5.2 CONCLUSIONS ................................................................................................................................... 31 

5.3 RECOMMENDATIONS ...................................................................................................................... 31 

REFERENCES ........................................................................................................................................... 32