Expression of c-fos and oxidative stress on brain of rats reared on food from mercury-selenium coexisting mining area

Wanshan mercury mine is the largest mercury deposit in Guizhou Province of China, but there were few reports on mercury toxic＂ effect in the mining area. In order to study the neurotoxicity of food from Wanshan mercury mine area and probe into the effect of food from Wanshan mercury miner area on the changes of brain oxidative damage and expression of c-fos gene. The rats were exposed to mercury contaminated food for 20 d. The content of malondialdehyde （MDA）, superoxide dismutase （SOD）, GSH-peroxidase （GSH-px） and Glutathione （GSH） in rat brain was measured, and the effect of mercury contaminated rice on the expression of c-los mRNA in rat brain and the expression of c-FOS protein in cortex, hippocampus were observed using reverse transcription polymerase chain reaction （RT-PCR） and immunocytochemical methods. The results showed the levels of GSH, MDA, SOD and of GSH-dependent enzymes in the rat brain changed between exposure groups and control group; The mercury polluted rice induced significantly the expression of c-los mRNA; the c-FOS positive cells in hippocampus and cortex of exposure groups were significant different from control group （P〈0.01）. It could be concluded that oxidative stress signals could contribute to the induction of immediate early genes （IEGs）; free radicals and their by-products might not only cause oxidative damage, but also influenced gene expression; IEGs c-fos participated in the toxicity process of brain injury by mercury polluted food.