Protective effect of vitamin E on genotoxicity of methylmercury

The cytogenetic effects of methylmercury (MeHg) producing chromosomal breakages, C-mitosis, and sister chromatid exchange are well documented. The present investigation was to determine whether vitamin E, which has been shown to exert a certain protective measure on the nervous system of animals exposed to methylmercury, also will diminish the genotoxicity of MeHg. Adult hamsters were given a daily injection (ip) of methylmercury chloride at a dosage of 2.0 mg/kg body weight (kg b.w.) and/or with 2.0 mg/kg b.w. vitamin E for 3 wk. All animals were sacrificed 5 d after the last day of MeHg exposure. Fibroblast cultures were established with cells obtained from skins of these animals. Chromosome preparations were made from these cultures and evaluated, using a double-blind system, for incidences of chromosomal breakage. It was found that all the fibroblast cultures grew well except from those animals treated with MeHg. Furthermore, while the saline control and vitamin E alone cultures showed no significant number of chromosomal breakages, cells from animals treated with only MeHg showed a high incidence of chromosomal damage (50% with 1 break and 15% with 2 or more breaks). Such chromosomal damage, however, was totally eliminated by vitamin E treatment (no chromosomal breakage was observed in cultures from MeHg/vitamin E animals). Our present study represents the first report on in vitro chromosomal damages as a result of in vivo MeHg exposure. Furthermore, our investigation also demonstrated the protective potential of vitamin E against genotoxicity of methylmercury.