Effects of methylmercury on zinc-thionein levels of rat liver

The induction of metallothionein synthesis by administration of methylmercury chloride was studied. A repetitive sc dose of methylmercury chloride to rats in amounts of 10 mg/kg/day for 3 days produced profund hypozincemia and 3-fold increase of 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, though its mechanism is not clear.This work was supported by Grant-in-Aid (1979) for scientific research from the Ministry of Education of Japan, the chief of the research group was Dr. T.Tsubaki, Institute of Brain Research, School of Medicine, Niigata University