Effects of methylmercury on zinc-thionein levels of rat liver.

The induction of metallothionein synthesis by administration of methylmercury chloride as studied. A repetitive sc dose of methylmercury chloride to rats in amounts of 10 mg/kg/day for 3 days produced profound hypozincemia and 3-fold increase in hepatic zinc bound to metallothionein by the initial 24 h. The incorporation of 35S-cysteine into hepatic metallothionein was about 4 times larger for rats treated with methylmercury, which was comparable with it for rats treated with cadmium, than for control rats. These results suggest the induction of de novo synthesis of metallothionein by administration of methylmercury, although methylmercury was found to be unable to bind to produced metallothionein both in vivo and in vitro. A stress produced by methylmercury administration appears to be involved in the induction of hepatic zinc-thionein by methylmercury, through its mechanism is not clear.