FACULTY OF VETERINARY MEDICINE

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    Effect of exposure and withdrawal on lead-induced toxicity and oxidative stress in cardiac tissues of rats
    (Society of Toxicology, India, 2016) Omobowale, T. O.; Oyagbemi, A. A.; Akinrinde, A. S.; Ola-Davies, O. E.; Saba, A. B.; Olukayode, O. J.; Adeolu, A. A.
    Lead poisoning continues to pose a serious health challenge and more significantly so in developing countries with ineffective waste disposal systems. Recent efforts at solving lead poisoning issues have seen entire towns being resettled from lead-contaminated areas. This study was designed to investigate whether withdrawal of lead exposure results in a resolution of toxic effects of lead in cardiac tissues. Adult male Wistar rats were exposed orally to lead acetate (PbA) at doses of 0.25, 0.5, and 1.0 mg/ml for 6-week duration, after which one-half was sacrificed and the remaining left for a further 6 weeks without lead treatment. Exposure of rats to PbA produced significant decline (P < 0.05) in the activities of antioxidant parameters, including superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione-S-transferase (GST), catalase (CAT), and reduced glutathione (GSH), whereas malondialdehyde (MDA) concentration was significantly elevated. Animals from the withdrawal period exhibited a similar pattern of alterations, with a significant (P < 0.05) reduction in GSH, GPx, and SOD and a significant elevation in MDA and H2O2 concentrations. However, GST activity was elevated, whereas CAT activity remained unaltered in the withdrawal period. The results of this study showed that cardiotoxicity indicated by induction of oxidative stress and reduction in antioxidant parameters failed to resolve upon withdrawal of lead exposure in male rats during the period of study.
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    Chemoprevention of aflatoxin B1-induced genotoxicity and hepatic oxidative damage in rats by kolaviron, a natural biflavonoid of garcinia kola seeds
    (Lippincott Williams & Wilkins, 2005) Farombi, E. O.; Adepoju, B. F.; Ola-Davies, O. E.; Emerole, G. O.
    The chemopreventive effects of kolaviron, a natural antioxidant biflavonoid from the seeds of Garcinia kola, on aflatoxin B1 (AFB1)-induced genotoxicity and hepatic oxidative damage was investigated in rats. Kolavironmadministered orally at a dose of 200 mg/kg once a day for the first 2 weeks and then 100 mg/kg twice a day for the last 4 weeks of AFB1 (2 mg/kg, single dose, intraperitoneal) treatment reduced the AFB1-increased activities of aspartate amino transferase (AST), alanine amino transferase (ALT) and gamma glutamyltransferase (c-GT) by 62%, 56% and 72% respectively. Malondialdehyde (MDA) formation and lipid hydroperoxide (LHP) accumulation were observed in the livers of AFB1-treated rats. Kolaviron significantly reduced the AFB1-induced MDA and LHP formation. Vitamins C and E were protective in reducing the increase in the activities of AST, ALT and c-GT as well as lipid peroxidation caused by AFB1 (P < 0.01). Administration of rats with kolaviron alone resulted in significant elevation in the activities of glutathione S-transferase, uridyl glucuronosyl transferase and NADH:quinone oxidoreductase by 2.45-, 1.62- and 1.38-folds respectively. In addition, kolaviron attenuated the AFB1-mediated decrease in the activities of these enzymes (P < 0.01). Pretreatment of rats with kolaviron, vitamins C and E alone did not exert genotoxicity assessed by the formation of micronucleated polychromatic erythrocytes (MNPCEs) (P> 0.05). Co-treatment of rats intraperitoneally with kolaviron (500 mg/kg) 30 min before and 30 min after AFB1 (1 mg/kg) administration inhibited the induction of MNPCEs by AFB1 (P < 0.001) after 72 h. While vitamin C was effective in reducing AFB1- induced MNPCEs formation, vitamin E did not elicit any antigenotoxic response. These results indicate kolaviron as effective chemopreventive agent against AFB1-induced genotoxicity and hepatic oxidative stress. Thus kolaviron may qualify for clinical trial in combating the menace of aflatoxicosis in endemic areas of aflatoxin contamination of foods.