The differential modulation of the enzymes of glutathione metabolism - Indication of overlapping effects of toxicity and repair in mouse liver and kidney after dietary treatment with methyl mercury and sodium selenite

The effect of methylmercury (MM) and MM plus sodium selenite (SE) on the activity of various GSH-dependent enzymes was studied in the liver and kidney of mice. Ten groups of mice were fed diets containing graded proportions of MM, alone or with graded quantities of SE. GST, GSH-Px, and GSSG-RED were assayed in the cytosolic fraction of liver and kidney homogenates. After treatment with MM, instead of the expected decrease in enzyme activities, an increase was observed in the kidney and a small decrease in the liver with no dose-response relation in either organ. In protected groups, a general pattern of induction was observed in both organs, but again there was little evidence of dose-response relationships. Detailed analysis of the results suggests that the effects observed were not directly caused by MM or SE but are the resultant of complex interactions presumably related to contemporaneous mechanisms of damage and repair. © 1993 Humana Press Inc.