In vivo Fatty Acid Synthesis in Adipose Tissue and Liver of Meal-Fed Rats.

Abstract

The effect of meal-feeding (access to food for a single daily 2-hr. period) on lipogenesis has been determined in intact rats. As previously observed with adipose tissue and liver in vitro, meal-fed rats had a markedly enhanced capacity to convert glucose-U-14C to fatty acids. The incorporation of glucoes-l4C into fatty acids was 200-fold higher in epididymal adipose tissue and 9-fold higher in liver of meal-fed as compared to nibbling (ad libitum-fed) rats. The radioactivity in adipose tissue, liver and serum fatty acids re-mained unchanged between 3 and 6 hr. after the initiation of the meal but increased between 6 and 9 hr. A possible explanation for this increase in fatty acid radioactivity is suggested. The probable contribution of liver and adipose tissue to total fatty acid synthesis under these experimental conditions was calculated from the observed incorporation of glucose-U-l4C. It was estimated that in the nibbling rat adipose tissue synthesized between50 and 90% of the fatty acids, and when lipogenesis was stimulated by meal-feeding, adipose tissue accounted for at least 95% of the total fatty acids synthesized. Serum glucose was similar for meal-fed and nibbling rats as were serum and liver total lipids and cholesterol.