Sites of Action of β-Melanocyte Stimulating Hormone in Aldosterone Biosynthesis in the Rat

Abstract

The sites of action of β-melanocyte stimulating hormone (β-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 μM) completely blocked aldosterone production stimulated by sodium depletion, AII, ACTH, and β-MSH. β-MSH (1 μM) significantly stimulated pregnenolone production (early step) and the conversion of corticosterone to aldosterone (late step) in aldosterone biosynthesis. The effect of β-MSH was similar to A11 and ACTH. Sodium depletion enhanced the effect of β-MSH only on the late step in aldosterone biosynthesis. In conclusion, β-MSH stimulates both the early and late steps of aldosterone biosynthesis. These results suggest that β-MSH or peptides containing β-MSH may play a role in the regulation of aldosterone production.