Vasoactive intestinal polypeptide and the nervous system: immunohistochemical evidence for localization in central and peripheral neurons, particularly intracortical neurons of the cerebral cortex.

Immunohistochemical studies on rat brain revealed large numbers of vasoactive intestinal polypeptide (VIP)-positive nerve cell bodies all over the limbic cortex and neocortex. Large numbers of nerve terminal plexus' were found within all layers of the limbic cortex, but mainly within layers II-IV of the neocortex. Thus, association neurons probably exist in the cerebral cortex which store VIP or VIP-like peptides, making possible a role for such peptides in higher nervous processes. A neuroendocrine function may also be postulated in view of the presence of VIP-positive terminals in the central amygdaloid nucleus, suprachiasmatic nucleus, medial preoptic nucleus and the anterior hypothalamic nucleus.