Effect of a high fructose diet on lipogenic enzyme activities of meal-fed rats.

The effect of a high fructose diet on lipogenic enzyme activities in liver, intestine and adipose tissue, and serum immunoreactive insulin level was studied in meal-fed rats. Male and female rats were meal-fed for 5 days with stock diet. After a 45-hour fast, they were meal-fed a high carbohydrate diet composed of fructose, glucose or cornstarch diet for 4 days. The daily food intake was similar within each sex (females 9-11 g/day and males 10-13 g/day). Only males fed glucose consumed significantly more food than any other group (12.9 g/day). Rats fed fructose had the greatest liver weight and total lipid content. The hepatic malic enzyme activity of both sexes was significantly higher in rats fed fructose than in those fed cornstarch. Small intestinal malic enzyme activity was largely unaffected by diet. The serum immunoreactive insulin level of rats fed fructose was the lowest, and the level in females was higher than in males fed fructose or glucose. The above results lead to the conclusion that the effect of feeding fructose compared to glucose is attributable to fructose itself and not differences in food intake.