FASTING AND POSTPRANDIAL CHANGES IN DETERMINANTS OF TRIACYLGLYCEROL METABOLISM IN RATS GIVEN MEALS HIGH IN STARCH OR SUCROSE

Some of the determinants of triacylglycerol metabolism were evaluated in the fasted state as well as postprandially in animals fed a meal high in either starch or sucrose, after having fed ad libitum for four weeks diets that had the same composition as the test meal. The postprandial rise in serum insulin and triacylglycerol levels were maximal 30 min and two hours after meal intake, respectively, regardless of the nature of the dietary carbohydrate. The high sucrose diet elicited postprandial hypertriacylglycerolemia, as well as fasting and postprandial hyperinsulinemia, compared to the high starch diet. Serum cholesterol concentrations were not altered after meal intake. Although serum total cholesterol levels were similar in both dietary groups, chronic consumption of the high sucrose diet increased the proportion of unesterified to esterified cholesterol in lipoproteins of lower densities. Fasting hepatic triacylglycerol secretion rate was 36% higher in the sucrose than in the starch cohort. Fasting postheparin plasma lipoprotein lipase activity was 19% lower in the animals fed the high sucrose meal, compared to those receiving the high starch meal, whereas hepatic triacylglycerol lipase was unaltered by diet. These results suggest that intake of a high sucrose meal following chronic ingestion of the same diet elicited the secretion of particles by the liver that were richer in triacylglycerols and unesterified cholesterol. Higher fasting rates of secretion of triacylglycerols by the liver of sucrose fed animals without hypertriacylglycerolemia suggests that the decrease in lipoprotein lipase activity did not impair the overall capacity for triacylglycerol hydrolysis in the fasting state. © 1990 Pergamon Press plc.