THE ROLE OF NEUROPEPTIDES IN THE REGULATION OF ADRENAL ZONA-FASCICULATA RETICULARIS FUNCTION - EFFECTS OF VASOACTIVE INTESTINAL POLYPEPTIDE, SUBSTANCE-P, NEUROPEPTIDE-Y, MET-ENKEPHALIN AND LEU-ENKEPHALIN AND NEUROTENSIN ON CORTICOSTERONE SECRETION IN THE INTACT PERFUSED RAT ADRENAL-GLAND IN-SITU

There is much evidence to suggest that glucocorticoid secretion may be influenced by the splanchnic innervation to the adrenal gland, and that this effect may be mediated by neuropeptides. The present studies investigated the effects of several neuropeptides on corticosterone secretion by the intact perfused rat adrenal gland in situ. Both vasoactive intestinal polypeptide and Met-enkephalin caused a dose-dependent increase in corticosterone secretion, with a maximum response of 450% and 370% increment in corticosterone respectively. Of the other peptides tested, Leu-enkephalin, substance P and neurotensin all stimulated corticosterone secretion, with a maximum response of around 160% increase in each case. Neuropeptide Y on the other hand, had only a minor effect, which was only apparent over a small dose range. These results support the theory that adrenal neuropeptides may have a role in the regulation of glucocorticoid secretion.