The distribution of vasoactive intestinal peptide in the rat adrenal cortex and medulla

There is increasing evidence for the role of the autonomic nervous system in the control of adrenal cortical function although the nature of the innervation is as yet unknown. In view of our expanding knowledge of the roles which peptidergic putative transmitters play in the autonomic nervous system, the present study was adrenal gland. Using immunocytochemical methods, VIP was found distributed in fibers in the adrenal cortex and medulla. VIP fibers were found primarily in the capsule and zona glomerulosa of the cortex and in small bundles in the medulla and appeared to innervate the parenchymal cells in both cases. Both colchicine pretreatment and ligation of the splanchnic nerve resulted in an increase in staining of fibers of the cortex and the medulla. Demedullated adrenals (regenerated) exhibited a reduced number of VIP fibers in the zona glomerulosa. It appears that the medullary and at least part of the cortical VIP fibers originate in the medullary VIP cell bodies which are regulated by the splanchnic nerve. The distribution of VIP suggests an important role for this peptide in both adrenal cortical and medullary function and a possible medullary modulation of adrenal cortical function.