Interaction of dietary carbohydrate and fat in the regulation of hepatic and extrahepatic lipogenesis in the rat

Abstract

1. In order to examine the interaction of dietary fat and carbohydrate in the regulation of lipid metabolism, we have studied hepatic and extrahepatic lipogenesis, and adipose tissue lipoprotein lipase (EC3.1.1.34) in rats fed on one of the following diets: a fructose-based diet containing 0 (F0) or 150 g maize oil (F15)/kg, or a glucose based diet containing 0 (G0) or 150 g maize oil (G15)/kg.2. The rats were meal-fed on the diets for 2 weeks after which the activities of a number of hepatic ‘lipogenic’ enzymes were measured and the activity of epididymal-fat-pad lipoprotein lipase. The activities of the lipogenic enzymes were: F0 > G0 > G15 > F15. Lipoprotein lipase activity was F0 = G0 = F15 = G15. The percentage of total body fatty acid synthesis which occurred in the liver was F0 > G0 > F15 > G15.3. We conclude that fructose-induced hypertriglyceridaemia is primarily a result of the increased hepatic synthesis rather than decreased adipose-tissue lipoprotein lipase activity.