Diurnal variations in response of rat liver tyrosine aminotransferase activity to food intake

Abstract

Effects of fasting and refeeding on the hepatic tyrosine aminostransferase activity were examined in rats that had been fed during the might. The tyrosine aminotransferase activity showed clear diurnal variations, with a maximal activity after the feeding time. The tyrosine aminotransferase rhythm persisted even under starvation, though the amplitude decreased remarkably. When the starved rats were refed at night, the tyrosine aminotransferase activity increased rapidly to a high level, but it increased slowly to a rather lower level when they were refed in daytime.