Effect of Dietary Fructose on Fatty Acid Synthesis in Adipose Tissue and Liver of the Rat

Publisher Website
Google Scholar
Abstract
Diets containing fructose, sucrose, or glucose as the only source of carbohydrate were fed to weanling rats for 2 to 3 weeks. In vitro lipogenesis from U-14C-glucose, U-14C-fructose or 1-14C-acetate by adipose tissue or liver slices was determined. Glucose was consistently incorporated into fatty acids more rapidly than fructose by adipose tissue, regardless of previous diet. Dietary fructose, fed as the sole carbohydrate or in combination with glucose, depressed adipose tissue lipogenesis from fructose and glucose. The activities of adipose tissue hexokinase, malic enzyme and citrate cleavage enzyme were also reduced by dietary fructose as compared to glucose. Fructose feeding increased the activities of hepatic malic enzyme, citrate cleavage enzyme and fructokinase. Lipogenesis from glucose was more rapid than from fructose in the liver of both the glucose- and fructose-fed animals. This observation is discussed in terms of the importance of substrate concentration in the incubation buffers used for in vitro studies. The data are interpreted to indicate a shift in the site of lipogenesis from the adipose tissue to the liver in fructose-fed animals. The possible role of hexokinase and fructokinase in this adaptive response is also discussed.