α-Amylase circadian rhythm of young rat parotid gland: An endogenous rhythm with maternal coordination

Abstract The circadian rhythm of α-amylase, E.C. 3.2.1.1. (α-1,4-glucan-4-glucanohydrolase) in the parotid glands of 25-day-old rats were studied under different experimental designs (fasting, reversed photoperiod, constant lighting conditions and treatment with reserpine and α-methyl- p -tyrosine). The rhythm of fasted rats did not change. There were modifications in the rhythm of rats submitted to a reversed photoperiod or treated with reserpine or α-methyl- p -tyrosine. The rhythm was present, with changes in the acrophase, in parotids of rats kept during their gestation and postnatal life in constant light or dark. Results suggest that the circadian rhythm of α-amylase in parotid gland of young rats is endogenous, synchronized by the photoperiod, and with maternal coordination.