Stimulation of rat pineal melatonin biosynthesis by N-acetylserotonin.

Rat pineal content of melatonin and related indoles (HPLC-fluorimetric procedure) was evaluated after injections of N-acetylserotonin, the immediate precursor of melatonin. The increase of melatonin and NAS but of no other indoles was observed after daytime (but not after nighttime) NAS administration. NAS-induced stimulation of melatonin biosynthesis was dose- and time-dependent. Maximum pineal melatonin levels after NAS injections were similar to physiological night time peak of melatonin levels. It is suggested that NAS-induced stimulation of pineal melatonin biosynthesis might be used as the physiological way of pineal gland stimulation for diagnostic and therapeutic purposes.