Acute administration of human chorionic gonadotropin reverts some of the inhibitory effects of an LH-RH agonist on testicular steroidogenesis

ABSTRACT

An LH-RH agonist, des-Gly10, [DTrp6]-LH-RH ethylamide (LH-RH A), was administered chronically to adult male cats in order to determine its effect on the steroidogenesis of the testis during the stimulatory action of human chorionic gonadotropin (hCG). Measurement of plasma testosterone levels were combined with the histochemical analysis of some steps of the testicular steroidogenic pathway. Chronic daily treatment with LH-RH A(20 *g/kg) for 67 days inhibited the early testicular response to hCG during the initial 0.5,1 and 24 h, whereas the inhibitory egffect was not observed 48 and 72 h after hCG administration.The maximal responses to hCG were obtained both in LH-RH A-treated animals and in their control group 48 and 72 h after hCG adnministration. Under these conditions, LH-RH A-treated cats showed no alteration in 3ß-hydroxysteroid dehydrogenase (3ß-Host-D) activity, whereas a marked inhibition was observed in the activity of alcohol dehydrogenase (ADII) which reflects the activity of 20,22-desmolase and/or 17,20-desmolase.