Acute and chronic methyl mercury poisoning impairs rat adrenal and testicular function.

Animals poisoned with methyl mercury (CH3Hg) exhibit stress intolerance and decreased sexual activity, which suggest both adrenal and testicular dysfunction. Adrenal and testicular function was studied in male rats after treatment with CH3Hg. In animals treated chronically, the adrenal glands were markedly hyperplastic with enlargement of the zona fasiculata. The mean basal serum levels of corticosterone were similar in experimental (17.8 micrograms/dl) and control (16.8 micrograms/dl) groups. However, with ether stress, experimental animals had a subnormal response, and the mean serum levels of corticosterone increased to only 23.9 micrograms/dl compared to 40.6 micrograms/dl in the controls. Exogenous ACTH stimulation produced a mean level of 19.0 micrograms/dl in the CH3Hg-treated animals and 49.7 micrograms/dl in the controls. In vitro studies demonstrated a defect in the conversion of cholesterol to pregnenolone. A profound impairment in swimming was partially reversed with glucocorticoid therapy. In animals treated with CH3Hg, serum testosterone was lower than normal in the basal state. Human chorionic gonadotropin stimulation increased the mean serum concentration of testosterone to 23.4 ng/ml in controls, but it was only 4.50 ng/ml in experimental animals. The data indicate that CH3Hg poisoning impairs adrenal and testicular steroid hormone secretion, which accounts in part for the diminished stress tolerance and decreased sexual activity observed in CH3Hg-intoxicated animals.