Influence of Periodicity of Eating on the Activity of Various Enzymes in Adipose Tissue, Liver and Muscle of the Rat

Abstract

The activities of various enzymes involved in the conversion of glucose to lipid were compared in tissues of meal-fed (access to food limited to a single daily 2-hour period) and nibbling (fed ad libitum) rats. Activities of hexokinase, pyruvate kinase, α-glycerophosphate dehydrogenase, acetyl CoA carboxylase and pyruvate carboxylase were significantly elevated in adipose tissue of meal-fed, as compared with nibbling rats. Muscle hexokinase activity, liver pyruvate carboxylase, and liver phosphoenolpyruvate carboxykinase activities were also enhanced by meal-feeding. The activities of liver glucokinase, hexokinase, pyruvate kinase, α-glycerophosphate dehydrogenase and acetyl CoA carboxylase, of muscle pyruvate kinase and α-glycerophosphate dehydrogenase, and of adipose tissue phosphoenolpyruvate carboxykinase were similar in meal-fed and nibbling animals. The possible significance of these observations to the metabolic economy of the meal-fed rat is discussed.