Sites of action of beta-melanocyte stimulating hormone in aldosterone biosynthesis in the rat.

The sites of action of beta-melanocyte stimulating hormone (beta-MSH) on aldosterone biosynthesis were studied using collagenase-dispersed adrenal glomerulosa cells from rats maintained on either normal or sodium-deficient diets for 2 weeks. Isolated cells were treated with a cyanoketone derivative (WIN 19,578) to isolate the early and late steps in aldosterone biosynthesis. WIN 19,578 (1 microM) completely blocked aldosterone production stimulated by sodium depletion, AII, ACTH, and beta-MSH. beta-MSH (1 microM) significantly stimulated pregnenolone production (early step) and the conversion of corticosterone to aldosterone (late step) in aldosterone biosynthesis. The effect of beta-MSH was similar to AII and ACTH. Sodium depletion enhanced the effect of beta-MSH only on the late step in aldosterone biosynthesis. In conclusion, beta-MSH stimulates both the early and late steps of aldosterone biosynthesis. These results suggest that beta-MSH or peptides containing beta-MSH may play a role in the regulation of aldosterone production.