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EFFECT OF PETROL FUMES EXPOSURE ON CYTOCHROME P450 IN MALE ALBINO RATS

BY

NNABUGWU STANLEY
(PG./MSc./08/49356)

DEPARTMENT OF BIOCHEMISTRY
UNIVERSITY OF NIGERIA
NSUKKA

SEPTEMBER, 2010

EFFECT OF PETROL FUMES EXPOSURE ON CYTOCHROME P450 OF ALBINO RATS

THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENT OF THE UNIVERSITY OF NIGERIA, NSUKKA FOR THE DEGREE OF MASTERS OF SCIENCE (M.Sc) IN ENVIRONMENTAL BIOCHEMISTRY AND TOXICOLOGY

BY

NNABUGWU STANLEY
DEPARTMENT OF BIOCHEMISTRY
UNIVERSITY OF NIGERIA
NSUKKA

SUPERVISORS: PROF. I.N.E ONWURAH
PROF. O OBIDOA
DEPARTEMNT OF BIOCHEMISTRY
UNIVERSITY OF NIGERIA
NSUKKA.
SEPTEMBER, 2010
CERTIFICATION
Nnabugwu Stanley, a post graduate student in the Department of Biochemistry, University of Nigeria, Nsukka with the registration number PG/MSc./08/49356 has satisfactorily completed the requirement for the degree of Masters of Science (MSc.) in Environmental Biochemistry and Toxicology.

The work embodied in this report is original and has not been submitted in part or full for any other diploma or degree of this or any other University.

…………………………..………………………… Prof. I.N.E Onwurah Prof. O. Obidoa (Supervisor) (Supervisor)

………………………………
Prof L.U.S Ezeanyika
(Head of Department)
DEDICATION
This work is dedicated to my immediate family, my parents Mr. & Mrs. Lawrence Nnabugwu, whose generous supports have been unending, and to my siblings Chi-Chi, Emmy, Dozie, Ifunanya and Obianuju who are always there for me.

Also to God almighty, who has always been my strength and support even in difficult times.

ABSTRACT
This study assessed the toxicological risk associated with an exposure to petrol vapour using rat as a model. The concentration of total liver cytochrome P450 served as a marker against control for un-exposed rats. Adult male wistar albino rats were randomly divided into 5 groups, each having 4 rats, and were exposed to vapours generated from direct evaporation of liquid unleaded petrol. The test groups were subjected to 3 hours, 6 hours, 9 hours and 12 hours of exposure per day for a total of 7 days, while the control group was not exposed to petrol vapour. The result showed that generally the level of cytochrome P450 increased in all the exposed groups when compared with the control. However a peak in cytochrome P450 concentration was reached at 0.63µm/ml in the group of rats exposed for 9 hours. There was no significant (p>0.05) change in cytochrome P450 concentration for the group of rats exposed for 3 hours and 6 hours, which had cytochrome P450 concentrations of 0.29µm/ml and 0.40µm/ml respectively after exposure to petrol fumes when compared with the control which had a cytochrome P450 concentration of 0.24µm/ml, but induction increased significantly (p<0.05) at 9 hours and 12 hours exposures with cytochrome P450 concentrations of 0.63µm/ml and 0.59µm/ml respectively. There was an increase in relative liver weight of the test animals (although not significant) which was not dependent on the hours of exposure. The pentobarbital induced sleeping time index also confirmed induction of microsomal enzyme, evident by the significant (p<0.05) reduction of sleeping hours of all the rats exposed to petrol vapour when compared with the control which was not exposed. The result of this investigation suggests that continuous inhalation of petrol fumes by an exposed individual may bring about a significant induction in cytochrome P450 enzyme, an indication that such individual is at a risk of petrol fume toxicity and other attendant health hazards such as cancer.

Acknowledgement
As I began to think of all the people whom I would like to express my appreciation for their support and suggestion in making this work a success, the list continued to grow. First, my thanks will go to my wonderful supervisors Prof. O. Obidoa and Prof. I. N.E Onwurah for the...
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