Effect of a high-fat diet on pancreatic insulin release, glucose tolerance and hepatic gluconeogenesis in male rats.

Abstract

Male rats were fed a high-fat diet (B) and compared with age and sex paired controls fed a standard diet (A). After an 18 hr fast, the plasma levels of glucose and insulin were lower in B than in A and the oral glucose tolerance were less in the B group. Insulin release in vitro by the pancreas of the rats on the high-fat diet was lower than in the controls. The formation of glucose-C14 from alanine-C11 (IO-' M) by liver slices was higher and that of lactic acid-C14, pyruvic acid-C14 and C14O2 was lower in B vs A when the animals were fed. After a 48 hr fast the A group shows higher gluconeogenesis than when fed, while B remains at the fed rate, in such a way that the formation of glucose-C14 in A vs B is not different when the animals were fasted. The decreased pancreatic insulin release in B could result in such an activation of hepatic gluconeogenesis, that a further increase with fasting is no longer possible.