HUMAN RECOMBINANT ACTIVIN-A MODULATES THE STEROIDOGENESIS OF CULTURED BOVINE ADRENOCORTICAL-CELLS

The effect of human recombinant activin-A on adrenal steroidogenesis was studied in cultured bovine adrenocortical cells. Activin-A significantly reduced cortisol output from ACTH (10nmol/l)-stimulated adrenocortical cells incubated for 24 hours in a dose-dependent manner (10, 100 and 500ng activin-A/ml suppressed cortisol secretion by 19, 33 and 40%), although no significant effect was observed in the case of 3 h incubation. Dehydroepiandrosterone (DHEA) secretion from ACTH-stimulated adrenocortical cells incubated for 24 h was also decreased by the addition of activin-A in a dose-dependent manner. (10, 100 and 500ng activin-A/ml suppressed DHEA secretion by 22, 56 and 58%). These inhibitory effects of activin-A (100ng/ml) on cortisol and DHEA secretion were partially blocked by the addition of follistatin/FSH-Suppressing Protein (200ng/ml). In contrast, activin-A treatment resulted in no significant decrease in aldosterone secretion. There were no significant effects of activin-A on basal secretions of cortisol, DHEA or aldosterone from adrenocortical cells. These results suggest that activin-A has a direct inhibitory effect on ACTH-stimulated bovine adrenocortical steroidogenesis.