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

Summary

The results of these studies show that lipogenesis is enhanced in liver and adipose tissue of intact rats as a consequence of meal-feeding. Fatty acid synthesis was approximately 200-fold higher in adipose tissue and 9-fold higher in liver of meal-fed as compared to nibbling rats. Increases in fatty acid radioactivity in adipose tissue, liver and serum were observed between 6 and 9 hours after the initiation of the meal. A possible explanation for these changes is proposed. Serum glucose and serum liver total lipid and cholesterol levels were also determined and no significant alterations due to meal-feeding were noted. From the observed rates of glucose-U-¹⁴C incorporation into liver and adipose tissue fatty acids an estimate was made of the relative importance of these tissues as sites of fatty acid synthesis. These calculations suggest that in the nibbling rat 50-90% of the fatty acids are synthesized in adipose tissue whereas when fatty acid synthesis is stimulated by meal-feeding, adipose tissue apparently accounts for about 95% of the total fatty acids synthesized.