Gonadotrophin suppression by steroids in normal, adult male rats.

Effect of subcutaneous administration of various doses of different steroids on serum levels of LH and FSH in normal, adult male rats were investigated. Each steroid was injected daily during 7 days in doses of 50, 25, 12.5 or 6.25 mug per 100 g body weight. Ring A 5alpha-reduced testosterone metabolites exerted high activity in the suppressing serum LH and FSH levels. 5alpha-Androstane-3beta, 17 beta-diol had in the doses tested, however, no such effects on serum gonadotrophins, Serum LH concentrations in normal rats appeared more sensitive to steroid treatment than serum FSH concentrations.