EFFECT OF HUMAN CHORIONIC GONADOTROPHIN ON TESTICULAR 5α-ANDROSTANE-3β-HYDROXYSTEROID DEHYDROGENASE, 3β-HYDROXYDEHYDROEPIANDROSTERONE DEHYDROGENASE AND ALCOHOL DEHYDROGENASE OF IMMATURE RATS
SUMMARY: Testicular enzymes related to steroid conversion were studied in infantile rats during sexual maturation, and the effect of human chorionic gonadotrophin (HCG) on the specific activities of the enzymes was analysed. Activity of 5α-androstane-3β-hydroxysteroid dehydrogenase, which increases between days 20 and 30, was markedly enhanced after administration of HCG. Alcohol dehydrogenase activity, which is related to 3β-hydroxysteroid dehydrogenase activity, also increased after HCG treatment. The other enzyme activities investigated, i.e. 3β-hydroxyde-hydroepiandrosterone dehydrogenase and testosterone-17β-dehydrogenase, did not respond to HCG administration. These results suggest that different enzymes are responsible for the conversion of 3β-hydroxylated androgenic steroids and that the testicular alcohol dehydrogenase is not identical to the 3β-hydroxysteroid dehydrogenase described here. On the assumption that HCG enhances enzyme activities indirectly by stimulating the synthesis of androgens which in turn produce the observed effect, different androgenic steroids (epiandrosterone, 5α-androstane-3,17-dione, 5α-dihydrotestosterone, 5α-androstane-3β,17β-diol) were tested for their ability to increase enzyme activities. None of these metabolites had an effect similar to that of HCG. The antiandrogen cyproterone (1,2α-methyl-6-chloro Δ4,6-pregnadien-17β-ol-3,20-dione) acetate, which was administered simultaneously with HCG, did not prevent the effect of HCG. From these results and other published reports it is concluded that in the testis of the infantile rat the metabolism of 5α-hydrogenated androgenic metabolites is stimulated by HCG.