INVOLVEMENT OF LIPOGENESIS IN THE LOWER VLDL SECRETION INDUCED BY OLIGOFRUCTOSE IN RATS

Dietary supplementation with oligofructose (OFS; 100 g/kg), a non-dige stible oligomer of beta-D-fructose, decreases serum triacylglycerols i n serum and VLDL of rats. In order to investigate the role of hepatic metabolism in the hypolipidaemic effect of OPS, male Wistar rats were fed on a standard diet with or without 100 g Raftilose(R) P-95/kg as O FS source for 30 d. OFS feeding (1) significantly decreased triacylgly cerol and phospholipid concentrations in both blood and liver, (2) inc reased the glycerol-3-phosphate liver content but decreased the hepati c activity of glycerol-3-phosphate acyltransferase (EC 2.3.1.15), sugg esting a decrease in acylglycerol synthesis, (3) did not affect the bl ood non-esterified fatty acid concentrations, but (4) reduced by 54% t he capacity of isolated hepatocytes to synthesize and secrete triacylg lycerols from labelled acetate; the activity of fatty acid synthase, a key lipogenic enzyme was also significantly decreased. These findings suggest that OPS decreases serum triacylglycerols by reducing de novo fatty acid synthesis in the liver; the lower insulin level in the ser um of OPS-fed rats could explain, at least partly, the metabolic effec t induced by such non-digestible carbohydrates.