Stimulation of protein and RNA synthesis by methylmercury chloride in the liver of intact and adrenalectomized rats.

(1) A single injection of methylmercury chloride in the rat (10-50 mg/kg) increased both in vivo and in vitro rates of 14C-leucine incorporation into the protein of the post-mitochondrial supernatant fraction of the liver. In contrast, no stimulation of protein synthesis was observed in the brain of the methylmercury-treated rats. (2) Methylmercury administration also stimulated RNA polymerase activities in isolated hepatic nuclei, stimulation of Mg-dependent activity being higher than that of Mn-dependent activity. (3) In experiments with adrenalectomized rats, it was found that the stimulatory effect of methylmercury on protein and RNA synthesis in the liver was mediated partly through the adrenal gland. (4) Analysis of serum by starch-block electrophoresis revealed that synthesis of all serum proteins, including albumin and alpha-gamma globulin fractions, was stimulated by methylmercury treatment. (5) These results suggest that the observed effects of methylmercury on the liver depend on mechanisms other than enhancement of the synthesis of acute-phase proteins.