EFFECTS OF JUVENILE-HORMONE ON MAMMALIAN STEROIDOGENESIS

The effects of juvenile hormone-III (JH-III) and the JH analogue 2-(4- phenoxyphenoxy)-ethoxytetrahydropiran on testicular steroidogenesis we re studied. By using cultured MA-10 Leydig tumor cells as a model, the se compounds were found to be potent inhibitors of LH/hCG steroidogeni c action in a dose-dependent manner. Scatchard plot analysis of the bi nding data indicated that the JH analogue did not significantly alter the affinity nor the number of hCG binding sites, as well as GTP bindi ng to plasma membranes. JH analogue inhibited the stimulatory action o f both cholera toxin and forskolin on cAMP production and the concomit ant steroidogenic response. JH analogue inhibited (Bu)(2)cAMP-stimulat ed progesterone synthesis, indicating that a process downstream to the adenylyl cyclase in the steroidogenic pathway is also affected.