Effects of high-fructose diet on lipogenic enzymes and their substrate and effector levels in diabetic rats.

When rats adapted to a stock diet were fed on various high-carbohydrate diets, the hepatic activities of glucose-6-phosphate dehydrogenase, malic enzyme and acetyl-CoA carboxylase were more greatly increased by fructose than by any other carbohydrate. Even in the diabetic state, the enzyme activities were somewhat increased by fructose feeding. After feeding on the diets for 9 days, the hepatic concentrations of intermediates of carbohydrate metabolism were generally lower in the diabetics than in the normals. Moreover, in both the normal and diabetic rats, the concentrations of fructose-1-phosphate, acetyl-CoA, citrate and malate were increased by fructose as were the enzyme activities. These results suggest that the metabolic pathway of fructose is predominant with respect to that of glucose and consequently lipogenesis may be able to be increased in the fructose-fed rats.