Comparison of α-linolenate and oleate in lowering activity of lipogenic enzymes in rat liver: Evidence for a greater effect of dietary linolenate independent of food and carbohydrate intake

Abstract

The role of polyunsaturated fatty acids in the regulation of lipogenesis has been the subject of considerable speculation. To determine whether a polyunsaturated fatty acid has a greater effect than a monounsaturated fatty acid in reducing activities of lipogenic enzymes in rats fed a high-carbohydrate, fat-free diet (Muto, Y. and Gibson, D. M. (1970) Biochem. Biophys. Res. Commun. 38, 9–15) or whether the effect of polyunsaturated fatty acids is only indirect (Gozukara, E. M., Frohlich, M. and Holten, D. (1972) Biochim. Biophys. Acta 286, 155–163) through reduction of food and carbohydrate intake, the effects of α-linolenate or oleate supplementation on the activities of lipogenic enzymes in liver were compared under conditions of equalized food intake (pair-feeding). In comparison with oleate supplementation, linolenate supplementation significantly reduced the activities of liver glucose-6-phosphate and 6-phosphogluconate dehydrogenases, fatty acid synthetase, malic enzyme and citrate lyase in fasted-refed rats or in essential fatty acid-deficient rats pair-fed during the supplementation period. These results provide firm evidence for the hypothesis that polyunsaturated fatty acids are more effective than monoenoic or saturated fatty acids in reducing the activity of lipogenic enzymes in liver.