Methylmercury poisoning induces oxidative stress in the mouse brain.

C57BL/6J mice were intoxicated by injection of 2.5 mg/kg body wt of methylmercuric chloride (MMC) daily for 3, 7, and 14 days, and the relative concentrations of superoxide and hydrogen peroxide and the specific activity of superoxide dismutase (SOD) were determined in various cellular fractions of the brain. High brain levels of Hg were associated with significantly increased amounts of superoxide and hydrogen peroxide by Days 3, 7, and 14 and with markedly reduced SOD activity by Days 7 and 14. Such a rise in the levels of reactive oxygen species indicates the induction of oxidative stress within brain tissue. This suggests that suppression of antioxidant activity, including that of SOD and glutathione, together with disturbances in the mitochondrial electron transport chain, may contribute to the induction of oxidative stress in the mouse brain following MMC poisoning.