title: Photoperiodic regulation of serotonin N-acetyltransferase activity in the pineal gland of the chicken.
abstract: 1. In continuous light, serotonin N-acetyltransferase activity in the pineal gland of 16-day-old chicks was reduced to about a half of the usual nocturnal level only in the first day, but no suppressive effect by the light was observed throughout the following 2 days. 2. In continuous darkness, circadian N-acetyltransferase rhythm persisted for three consecutive days. 3. In continuous light, the phase of N-acetyltransferase rhythm in chick pineal delayed remarkably for three consecutive days, while the phase delayed in a lesser degree in continuous darkness. 4. The rhythm of N-acetyltransferase activity in the pineal gland of 13-day-old chicks was entrainable to a shorter (8L: 8D) and a longer (18L: 18D) photoperiod as in a 12L: 12D photoperiod, but a shorter photoperiod such as a 3L: 3D photoperiod failed to change the pre-established 12L: 12D rhythm.
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism*; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D002645:Chickens; D002940:Circadian Rhythm; D003624:Darkness; D008027:Light; D008297:Male; D010870:Pineal Gland / Q000201:enzymology*
chemical_list: D000123:Acetyltransferases; D001191:Arylamine N-Acetyltransferase