Vasoactive intestinal peptide stimulation of pineal serotonin-N-acetyltransferase activity: general characteristics.

Vasoactive intestinal polypeptide (VIP) stimulates basal serotonin-N-acetyltransferase (NAT) activity in pineals in organ culture and enhances the effects of catecholamines in inducing the enzyme. VIP appears to act postsynaptically; its action is independent of the beta receptor and is dependent upon protein synthesis. Its effects may be mediated by a receptor. The magnitude of the pineal response to VIP varies with age, is greater in pineals maintained in 48-h organ culture than in those in acute culture, and can be detected in pineals from newborns after 48-h organ culture. Intravenous administration of VIP can increase pineal NAT activity in vivo.