Differential effects of diets that provide different lipid sources on hepatic lipogenic activities in rats under ad libitum or restricted feeding

This work was designed to study the effect of different lipid sources on he patic lipogenic enzyme activity in rats fed ad libitum or energy-controlled diets. Male Wistar rats were fed diets: containing 40% of energy as fat (o live oil, sunflower oil, palm oil, or beef tallow) for 4 wk. In experiment 1 rats had free access to food, and in experiment 2 rats were fed a control led amount of food. In both experiments, rats fed the olive oil diets had h igher activities of glucose-6-phosphate dehydrogenase, malic enzyme, fatty acid synthase, and acetyl-CoA carboxylase (P < 0.05) than rats fed the othe r fats. It is unlikely that this effect could be attributed to the stimulat ion by insulin or triiodothyronine because serum values did not differ amon g the groups. Enzymatic activities were positively and significantly correl ated with liver triacylglycerol content, but not with serum triacylglycerol levels. No interaction between lipid source and feeding protocol was found . Oleic acid and components in olive oil other than fatty acids, such as ph ytosterols, may account for the effects of dietary fat on lipogenic enzyme activity. (C) Elsevier Science Inc. 2001.