IN-VIVO EFFECTS OF HYPERINSULINEMIA ON LIPOGENIC ENZYMES AND GLUCOSE-TRANSPORTER EXPRESSION IN RAT-LIVER AND ADIPOSE TISSUES

Chronic hyperinsulinemia with maintenance of euglycemia was imposed on normal rats for 4 days. In white adipose tissue, hyperinsulinemia res ulted in a twofold increase in GLUT4 protein and mRNA and a sixfold to 15-fold increase in fatty acid synthase (FAS) and acetyl coenzyme A ( CoA) carboxylase (ACC) activity, respectively. Lipogenic enzyme mRNA w as also markedly increased (20 to 30-fold). This was specific for whit e adipose tissue and was not observed in brown adipose tissue. In the liver, hyperinsulinemia was accompanied by a threefold increase in glu cokinase (GK) activity and mRNA and by a threefold to fivefold increas e in lipogenic enzyme activities and mRNA. In agreement with the chang es in lipogenic activities, lipogenesis was markedly increased in whit e adipose tissue and liver of hyperinsulinemic rats. The data strongly suggest that in the rat, insulin is a driving force leading to increa sed lipid synthesis in liver and white adipose tissue. Copyright (C) 1 995 by W.B. Saunders Company