In vitro toxicity induced by methylmercury on sympathetic neurons is reverted by l-cysteine or glutathione

Methylmercury (MeHg) is related to several deleterious effects on the vertebrate nervous system and part of these effects are through interaction with sulfhydryl (-SH) group found in cellular proteins. We decided to characterize the dose-dependent effect of MeHg on the neurotoxicity and the neurite outgrowth induced effects on chick sympathetic neurons dissociated and purified in culture. In this model, MeHg inhibited neurite outgrowth (1-10 μM) and induced cell death (1-10 μM) after 48 h in culture. Since metal toxicity often generates reactive oxygen species, we tested if antioxidant compounds such as glutathione (GSH) or l-cysteine (l-cys) could block the deleterious effects promoted by MeHg. l-Methionine, another sulfur-containing amino acid, but without a SH group, was also used in this work. We show that GSH (10-100 μM) and l-cys (100 μM), but not l-methionine (100 μM), fully blocked neurite degeneration and sympathetic neuron cell death in culture.