Testosterone metabolism by incubated rat testes after chronic LHRH treatment

Adult male rats were injected 4 or 8 days with LHRH agonist. After sacrifice the testes were incubated in vitro with or without [4-14C]testosterone. After LHRH-administration the endogenously produced amounts of testosterone and of 7 alpha-hydroxytestosterone, the main testosterone metabolite normally found on incubation of adult rat testes, were drastically reduced when compared with controls. hCG, injected to rats 2 h before sacrifice, increased steroid production. In the LHRH-treated rats, however, the amounts of testosterone and of 7 alpha-hydroxytestosterone produced were much less while an important formation of 5 alpha-androstanediol was observed. The testes of LHRH treated rats metabolized [4-14C]testosterone to a large extent to 5 alpha-reduced and unextractable metabolites while the formation of 7 alpha-hydroxylated metabolites was much reduced. It is concluded that prolonged LHRH treatment provokes not only a depression of the testosterone production but has also an influence on the testicular metabolism pattern of testosterone resulting in a proportionally increased production of 5 alpha-reduced steroids and unextractable metabolites while the formation of 7 alpha-hydroxylated steroids is inhibited.