Changes in Very Low Density Lipoprotein Particle Size and Production in Response to Sucrose Feeding and Hyperinsulinemia*

Publisher Website
Google Scholar
Abstract
The effects of chronic (2 wk) hyperinsulinemia on the production of very low dentisy lipoprotein (VLDL) triglyceride and VLDL particle size were examined. Hyperinsulinemia was induced by a constant s.c. infusion of 6 U porcine insulin/day from an osmotic minipump. To avoid profound hypoglycemia, these rats received chow plus 10% sucrose in their drinking water. Therefore, 2 control groups were examined; one receiving chow plus the same amount of sucrose (high carbohydrate control) and the other receiving chow only (chow control). The constant infusion model was compared to a previously reported model of hyperinsulinemia. In that model, NPH insulin was injected for 2 wk twice daily in incrementally increasing doses (final dose, 6 U/day) into rats that were also fed chow and given 10% sucrose drinking water. Results with the injection model were similar to those preciously reported: an increase in triglyceride production in face of a decrease in FFA [free fatty acid], a minimal decrease in serum triglyceride, and some decrease in serum glucose. The infusion model produced the same increase in triglyceride production and decrease in fatty acid concentration. However, it differed in producing an increase in serum triglyceride and no change in serum glucose. Since there was no hypoglycemia in the infusion model, it was unlikely that VLDL changes were caused by an increase in counter regulatory hormones. VLDL particle size was increased in the high carbohydrate controls. Changes in sucrose supplementation led to the production of more triglyceride-filled VLDL particles. Hyperinsulinemia was not accompanied by any further increase in particle size. Thus, the hyperinsulinemia-induced increase in VLDL-triglyceride production was accompanied by an equivalent increase in VLDL particle production.