Incorporation of [ 14C 6]glucose and [9,10- 3H]palmitic acid in vitro into lipids of adipose tissue from essential fatty acid-deficient rats

Abstract

The simultaneous incorporation of labelled glucose and palmitic acid into lipids has been investigated in vitro in epididymal fat pads of rats fed essential fatty acid-deficient diet, in order to obtain information on possible metabolic differences brought about by essential fatty acid-deficiency in adipose tissue. It has been found that the incorporation of both precursors, but especially of glucose, is greater into adipose tissue lipids (mostly triglycerides) in rats fed essential fatty acid-deficient diet than in controls, indicating a greater triglyceride synthesis in these animals. Lipid synthesis in the adipose tissue of essential fatty acid-deficient animals, however, does not seem to differ qualitatively from that of controls. The distribution of radioactivity among the lipid components suggests that no change in the metabolic utilization of essential fatty acids for the synthesis of neutral lipids occurs. Also the incorporation of palmitic acid and glucose into glycerides is similarly affected in control and essential fatty acid-deficient animals during fasting or nicotinic acid or theophylline treatment. It may be concluded that the increased free fatty acid mobilization in essential fatty acid-deficient rats is not a consequence of decreased triglyceride synthesis. On the other hand, the enhanced lipolysis observed is related to the increased synthesis of triglycerides in adipose tissue. The relationship between these observations and the role of prostaglandins, which are synthesized from essential fatty acids in adipose tissue, is discussed.