HORMONAL-REGULATION OF HUMAN TESTICULAR INHIBIN-ALPHA AND BETA(B)-SUBUNIT MESSENGER-RNAS

Changes in messenger ribonucleic acids (mRNAs) of human testicular inhibin alpha and beta(B) subunits induced by human menopausal gonadotropin (hMG) and human chorionic gonadotropin (hCG) were assessed in vivo and in vitro. After a single administration of hMG, inhibin alpha mRNA in the human testis significantly increased, whereas inhibin beta(B) mRNA remained unchanged. Administration of hCG induced a slight increase in inhibin alpha mRNA without affecting inhibin beta(B) mRNA. In experiments in vitro using the testicular organ culture technique, an exposure to hMG for 24 hours induced a dose-related significant increase in inhibin alpha mRNA. Inhibin beta(B) mRNA was not affected by either hCG or hMG exposure. These results indicate that luteinizing hormone (hCG) as well as follicle stimulating hormone (hMG) may play a role in the regulation of human testicular inhibin alpha mRNA, although the mechanism of the LH action is not clear.