Mechanism of carbohydrate-induced hypertriglyceridemia: plasma lipid metabolism in mice

A group of mice were fed on a basal diet for 2 wk and thereafter maintained on a fat free high sucrose or starch diet for 5-6 wk. Hypertriglyceridemia was induced in the mice on feeding the high carbohydrate diets. The triglyceride levels reached maximum in 12 and 14-18 days on high sucrose and starch diets, respectively. This was associated with increased pre-beta-lipoproteins in plasma. Though males had higher levels of triglycerides than females on both the diets, this attained statistical significance only in the sucrose-fed group. Cholesterol and phospholipids recorded a significant increase only towards the end of the experimental period. The plasma lipid levels correlated with their secretion rates from the liver following an injection of Triton WR 1339. Furthermore, the hypertriglyceridemia appeared to be due to defective plasma triglyceride removal as seen by the reduced postheparin lipolytic activity (PHLA) of plasma and decreased triglyceride removal (intravenous fat tolerance test) in these animals. The triglycerides returned to almost normal levels when feeding was continued on the diets. During this adaptation, PHLA and fat tolerance of animals increased significantly. Higher triglycerides in the sucrose group seem to be due to a higher rate of secretion as well as slower removal of triglycerides in this group. The sex difference noticed in the plasma triglycerides at peak hypertriglyceridemia appeared to be mainly due to sex difference in removal rates. Blood sugar raised significantly in the animals maintained on both the diets.