Free radicals and antioxidant status in rat liver after dietary exposure of environmental mercury.

Potential health effect of dietary exposure to environmental mercury was examined in this study. Dietary exposure significantly increased content of reduced glutathione (GSH) and activity of glutathione peroxidase (GSH-Px) in rat liver at 7 or 20 days (P<0.05; P<0.01), but parameters droped to normal levels after 90 days of exposure. The early increases of the two antioxidants were partly associated with the co-accumulated selenium. However, activity of superoxide dismutase (SOD) was observed significantly decreased after 30 and 90 days of exposure (P<0.05, P<0.05). Changes of antioxidants were paralleled by the induction and aggravation of free radicals in rat liver at 30 and 90 days (P<0.01, P<0.01), increased nitric oxide (NO) content at 90 days (P<0.01). The excess availability of free radicals and the decreased levels of antioxidants resulted in a significant increase of malonyldialdehyde (MDA) after 90 days of exposure, indicating the aggravation of hepatic oxidative status. A number of biomarkers were required to monitor and minimize the health risk for the local population.