Activités enzymatiques du foie et du tissu adipeux pendant le jeûne total ou le jeûne protéique et la réalimentation équilibrée ultérieure

Abstract

Activities of enzymes involved in glucose phosphorylation, glucokinase (EC 2.7.1.2.), hexokinase (EC 2.7.1.1.), glucose 6-phosphatase (EC 3.1.3.9.), and in NADPH production, glucose-6-phosphate dehydrogenase (EC 1.1.1.49), 6-phospho-gluconate dehydrogenase (EC 1.1.1.44), NADP Malate-dehydrogenase (EC 1.1.1.40), were studied in rat liver and adipose tissue during fasting-refeeding and protein depletion-repletion. Fasting induced an increased activity of glucose-6-phosphatase and a sharp decrease in all other activities in both liver and adipose tissue hexokinase, dehydrogenases of the pentose shunt and NADP-Malate dehydrogenase. These activities have long been associated with adaptative hyperlipogenesis. In our experiments adaptation was more evident in liver than adipose tissue. On the other hand, protein-depletion alone did not change glucose availability or glucose 6-phosphatase activity. Protein repletion did not induce any hyperactivity of glucokinase, adipose tissue hexokinase, nor dehydrogenases, evidencing a lack of hyper-lipogenesis.