Non-ACTH POMC fragments stimulate aldosterone production by human adrenal cells in vitro

The possibility that non-ACTH proopiomelanocortin-derived fragments may stimulate aldosterone production has previously been studied using nonhuman cells with inconsistent results. We have examined the response of aldosterone to beta-endorphin (beta-End) and joining peptide (JP) and compared these with the response to ACTH using eight cell suspensions prepared from human adrenal glands. ACTH, 10(-6), 10(-8), and 10(-10) M, consistently stimulated aldosterone accumulation above that occurring in unstimulated cells (150 +/- 83, 120 +/- 62, and 77 +/- 32 fmol/10(4) cells above basal, respectively; mean +/- SE; p < 0.05). beta-End significantly stimulated aldosterone production at 10(-6) and 10(-8) M (114 +/- 84 and 50 +/- 24 fmol/10(4) cells above basal; p < 0.05); 10(-10) M beta-End did not provide significant stimulation. Furthermore, JP stimulated aldosterone biosynthesis (41 +/- 16 fmol/10(4) cells above basal; p < 0.05), only at the highest concentration used, 10(-6) M. The addition of 10(-8) M ACTH plus 10(-6) and 10(-10) M beta-End to human adrenal cells yielded values significantly greater than those achieved with either agent alone (267 +/- 152 and 183 +/- 89 fmol/10(4) cells above basal; p < 0.05). These data indicate for the first time that beta-End and JP have the capacity to stimulate aldosterone production in human adrenal cells in vitro. The physiological and potential clinical significance of these observations has yet to be elucidated.