title: Regulation of the circadian rhythm in pineal melatonin production.
abstract: The pineal gland exhibits a circadian rhythm in the activity of N-acetyltransferase, the enzyme responsible for the rhythmic production of melatonin. Our data are consistent with the hypothesis that the N-acetyltransferase rhythm is regulated by a two-oscillator pacemaker. The evening N-acetyltransferase rise is controlled by an evening oscillator coupled to dusk, the morning decline by a morning oscillator coupled to dawn. The phase-relationship between both oscillators may determine the period of high night N-acetyltransferase activity and hence the period of elevated melatonin level. This period is different during long and short days and it may provide animals with information about environmental day duration.
mesh_terms: D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism; D002940:Circadian Rhythm / Q000528:radiation effects; D008027:Light; D008550:Melatonin / Q000096:biosynthesis*; D010870:Pineal Gland / Q000378:metabolism* / Q000528:radiation effects; D051381:Rats
chemical_list: D001191:Arylamine N-Acetyltransferase; D008550:Melatonin