PANCREATIC-POLYPEPTIDE STIMULATES RAT ADRENAL GLUCOCORTICOID SECRETION BY ACTIVATING THE ADENYLATE CYCLASE-DEPENDENT SIGNALING PATHWAY

Pancreatic polypeptide (PP) concentration-dependently raised basal cor ticosterone and cyclic-AMP production of dispersed rat zona fasciculat a/reticularis adrenocortical cells, maximal effective concentration be ing 10(-7) M. 10(-7) M PP also significantly enhanced submaximally (10 (-12)/10(-11) M), but not maximally (10(-9)/10(-8) M) ACTH-stimulated corticosterone and cyclic-AMP release. Corticosterone responses to PP were abolished by the specific protein kinase A (PKA) antagonist H-89 (10(-5) M). The selective ACTH-receptor antagonist corticotropin-inhib iting peptide; (10(-6) M) annulled corticosterone response to 10(-9) M ACTH, but not to 10(-7) M PP. Collectively, our present findings indi cate that PP stimulates glucocorticoid secretion of rat adrenal glands , acting through specific receptors coupled, like those of ACTH, with the adenylate cyclase/PKA-dependent signaling pathway.