Sixty adult male Wistar rats weighing between 120 g and 140 g obtained from the Department of Biochemistry, University of Ibadan, Ibadan were used for this study. The animals were housed in plastic cages placed in a well-ventilated vivarium and subjected to natural photoperiod of 12-hr light: 12-hr dark. They were fed with rat chow and given drinking water ad libitum for a week before the commencement of the experiment. All the animals received humane care according to the conditions stated in the ‘Guide for the Care and Use of Laboratory Animals’ prepared by the National Academy of Science (NAS) and published by the National Institute of Health. The experimental protocols were carried out after approval by the University of Ibadan Ethical Committee.