Melatonin synthesis: adenosine 3',5'-monophosphate and norepinephrine stimulate N-acetyltransferase.

Treatment of cultured rat pineal glands with norepinephrine or dibutyryl adenosine 3',5'-monophosphate causes a six- to tenfold stimulation of N-acetyltransferase. This enzyme converts serotonin to N-acetylserotonin, the immediate precursor of melatonin. The increased synthesis of melatonin caused by norepinephrine treatment appears to be the result of stimulation of N-acetyltransferase by an adenosine 3',5'-monophosphate mechanism.