HELODERMIN STIMULATES INTRACELLULAR ACCUMULATION OF CYCLIC-AMP AND NORMAL-ACETYLTRANSFERASE ACTIVITY IN RAT PINEAL-GLAND

The effects of helodermin (HD) on the intracellular cyclic AMP (cAMP) accumulation and N-acetyltransferase (NAT) activity were examined using rat pineal glands. HD stimulated the pineal cAMP accumulation and NAT activity in a dose-dependent manner. The stimulatory potency of HD was nearly equal with that of vasoactive intestinal polypeptide (VIP). HD stimulation of pineal cAMP accumulation was further potentiated by an addition of 4-beta-phorbol 12-myristate 13-acetate (PMA). Our results suggest that HD is one of neurotransmitter candidates of the pineal gland, and support a hypothesis that neuropeptides play a role in regulating pineal function as well as norepinephrine.