Effects of Dietary Cholesterol on the Activity of Some Carbohydrate Metabolism Enzymes in the Liver of Rats

The effect of cholesterol-cholic acid feeding on the activity of several carbohydrate metabolism enzymes in the liver of rats was studied. Glu- cose-6-phosphate dehydrogenase, NADP-malic enzyme, hexokinase, glucokinase and pyruvate kinase activities were determined in the hepatic tissue from rats which were fed the following: a) sucrose diets containing 0 or 1% cholesterol + 0.5% cholic acid for 12 weeks and then killed while being fed ad libitum or refed after a period of starvation; b) sucrose or starch diets with or without cholesterol-cholic acid supplementation for 12 weeks and then killed in a fed state; and c) sucrose diets with or without cholesterolâ€"cholic acid supplementa tion for 12 days and killed in a fed state. The results show that liver glucokinase, glucose-6-phosphate dehydrogenase and NADP-malic enzyme activities were sig nificantly reduced by cholesterol-cholic acid feeding under all of the conditions tested. Hexokinase and pyruvate kinase were not significantly changed except when the rats were refed after a period of starvation. A dietary regimen of fast ing and refeeding elevated the activity of these two enzymes. The alterations in enzyme activities are interpreted as regulatory effects exerted by dietary choles terol-cholic acid supplementation. J. Nutr. 102: 1039-1044, 1972.