Dietary carbohydrates and synthesis and secretion of apolipoprotein B-containing lipoproteins in rat hepatocytes.

The influence of glucose-, sucrose- and starch-containing diets on the synthesis and secretion of lipoprotein in the density range of very-low-density lipoproteins (VLDLs) and low-density lipoproteins (LDLs) was studied via primary cultures of rat hepatocytes. Apolipoprotein B secreted by hepatocytes from rats fed a sucrose diet was significantly more than in rats fed starch or glucose. This was further confirmed by pulse labeling with [3H]leucine and chase study. Increased synthesis and secretion of cholesterol in lipoproteins of the VLDL and LDL density range and decreased synthesis and secretion of triglyceride in the VLDL fraction were observed in hepatocytes from sucrose-fed animals compared with those fed glucose. This indicates that the VLDL secreted by hepatocytes from sucrose-fed animals was richer in cholesterol but poorer in triglycerides than from glucose/starch- and glucose-fed animals. These findings also suggest an increase in the synthesis and secretion of apolipoprotein B by hepatocytes on sucrose feeding, indicating an association with an increase in cholesterogenesis.