A Diurnal Rhythmicity in Incorporation of Lysine into Rat Brain Regions

A number of studies in recent years have attempted to elucidate the effects of learning and environmental change on brain biochemistry, especially protein synthesis¹. There has also been much interest in the circadian rhythms exhibited by animals, at both the behavioural and biochemical levels (for a review see ref. 2). It therefore seemed of interest to determine whether or not such cyclical responses are reflected in intrinsic rates of protein synthesis. We describe here a diurnal rhythmicity in the incorporation of tritiated lysine into various brain regions and the liver.