Thymidine incorporation by cultured chick pineal glands is not subject to adrenergic regulation.

Norepinephrine is known to play a role in regulating the circadian rhythms of serotonin N-acetyltransferase activity and melatonin formation in the chick pineal gland. We have recently demonstrated that the cultured chick pineal exhibits a circadian rhythm in the incorporation of thymidine. In this study we show that this latter rhythm is not subject to adrenergic control.