RESUMO
Paraquat (PQ) is a toxic chemical that is widely used as an herbicide in developing countries. It has been described as a major suicide agent, thus leading to its ban or restriction in use by Environmental Protection Agency in some countries. There is no known chelating agent or antidote for PQ. This study investigated protective effects of antioxidant vitamins C, E and its combination in both pre-treatments and post-treatments. Pre-treatment of rats with vitamins C, E and C+E gave survival rates of 40%, 20%and 20% respectively while post-treatment gave 80%, 20% and 20% respectively when lethal dose (150mg/Kg) of PQ was administered. However, when sub-lethal dose (75mg/Kg) was administered, biochemical investigations revealed a significant (p<0.05) increase in cholesterol, SOD, CAT, POD and GPx activities, decreased total protein and triglyceride in PQ treated rats. The extent of lipid peroxidation as measured by malondialdehyde (MDA) concentration was more pronounced in the lung than in the liver. Histopathological investigations revealed proliferation of the bile duct and severe centrilobular necrosis in the liver and severe haemorrhage in the lungs of rats treated with PQ alone compared to the control. No visible lesion except hepatic regeneration and mild congestion of the liver and kidney of vitamin C post-treated rats were observed. The results also provided some evidence in respect of the potency of vitamin C post-treatment in conferring some level of protection against PQ-induced oxidative stress by modulating the extent of lipid peroxidation and antioxidant enzyme activities.