<b>VASOACTIVE INTESTINAL POLYPEPTIDE STIMULATES ADENYLATE CYCLASE AND SEROTONIN <i>N</i>-ACETYLTRANSFERASE ACTIVITIES IN RAT PINEAL <i>IN </i></b><b><i>VITRO </i></b>

Abstract

Vasoactive intestinal polypeptide (VIP) stimulated cyclic AMP formation in rat pineal gland with dose-dependency in vitro, though this effect was much less than that of norepinephrine. Bilateral ganglionectomy of the superior cervical ganglion did not inhibit the stimulatory effect of VIP in the gland. In the cultured pineal gland, VIP, like norepinephrine, markedly increased the activity of serotonin N-acetyltransferase, an-enzyme for melatonin synthesis. A dose of propranolol above lO""5 M inhibited VIP action, but a lower dose propranolol (lO"5 M) did not inhibit VIP stimulation of cyclic AMP formation in the pineal gland.