ALTERATIONS IN POSTPRANDIAL GLYCOGEN AND LIPID-SYNTHESIS IN CACHECTICTUMOR-BEARING RATS

Alterations in the postprandial metabolism of glucose were investigate d in groups of tumor-bearing rats and freely fed controls and in group s of normal rals whose food intake had been restricted to match that o f the tumor-bearing rats. A standard mixed meal was administered by ga vage, and the rate of incorporation of H-3 from (H2O)-H-3 into hepatic glycogen and into saponifiable lipids in the liver and adipose tissue was measured at intervals up to three hours after the meal. In tumor- bearing rals, the rate of glycogen synthesis rose by more than twice a s much as normal after the meal, while the normal rise in rates of fat ty acid synthesis was suppressed In contrast, in the rats whose food i ntake had been restricted, the postprandial rise in hepatic glycogenes is was suppressed and the rates of postprandial lipogenesis in liver a nd adipose tissue were increased. Thus the changes that were observed in the tumor-bearing animals did not represent a normal response to re duced food intake. Increased postprandial glycogenesis in tumor-bearin g rats is likely to be associated with increased gluconeogenesis, ther eby increasing energy expenditure. The prolonged high rate of hepatic glycogen synthesis may also delay the initiation of the next meal and thus contribute to the decrease in food intake in cancer cachexia.