GLYCERONEOGENESIS IN ADIPOSE TISSUE OF FASTED DIABETIC AND TRIAMCINOLONE TREATED RATS

Incorporation of [2‐14C]pyruvate into adipose tissue triglycerides was measured in fasted, diabetic and triamcinolone treated rats and related to the activity of enzymes active in the elaboration of glyceride glycerol. Incorporation of pyruvate into glyceride glycerol was increased in fasting and diabetes. The activity of phosphoenolpyruvate carboxykinase increased in parallel with the enhanced glyceroneogenesis, whereas the activity of pyruvate carboxylase changed in the opposite direction. After triamcinolone treatment, the activity of both enzymes was decreased as was the incorporation of [2‐14C]pyruvate into glyceride glycerol. In all experimental animals glutamate‐pyruvate transaminase activity in adipose tissue decreased, whereas the activity of glutamate‐oxaloacetate transaminase increased slightly. These results were interpreted as implying that the enhanced glyceroneogenesis in diabetes and fasting is related to the increase in phosphoenolpyruvate carboxykinase activity, whereas pyruvate carboxylase activity seems associated with changes in fatty acid synthesis. In contrast to adipose tissue, in the liver the activity of both enzymes of the dicarboxylic acid shuttle and of transaminases increased in the situations associated with enhanced gluconeogenesis. This finding is discussed in the light of possible differences in the availability of precursors for gluco‐ and glyceroneogenesis in the respective tissues. The role of glyceroneogenesis is pointed out, as one of the factors maintaining the balance between synthesis and breakdown of triglycerides in adipose tissue, particularly in conditions associated with rapid lipolysis. Copyright © 1969, Wiley Blackwell. All rights reserved