title: Regulation of the pineal melatonin concentration in the rat (Rattus norvegicus) and in the Djungarian hamster (Phodopus sungorus).
abstract: 1. Rapid changes of melatonin concentration in pineals of rats (Rattus norvegicus) after isoproterenol administration or in the course of a day were accompanied by parallel changes of N-acetyltransferase but not of hydroxyindole-O-methyltransferase activity. 2. In pineals of Djungarian hamsters (Phodopus sungorus) the evening and morning melatonin changes were also parallel with N-acetyltransferase changes. 3. In both species, melatonin concentration during its rise had approached the maximum earlier than N-acetyltransferase reached its highest activity. 4. It is proposed that the N-acetyltransferase rhythm drives the melatonin rhythm both in rats and in Djungarian hamsters; the maximum melatonin production may, however, depend also on hydroxyindole-O-methyltransferase activity and substrate concentration.
mesh_terms: D000121:Acetylserotonin O-Methyltransferase / Q000378:metabolism; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism; D002940:Circadian Rhythm; D006224:Cricetinae / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D010870:Pineal Gland / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains / Q000378:metabolism*
chemical_list: D000121:Acetylserotonin O-Methyltransferase; D001191:Arylamine N-Acetyltransferase; D008550:Melatonin; D007545:Isoproterenol