Postprandial modulation of lipoprotein lipase in rats with insulin resistance.

The purpose of this study was to determine whether the postprandial modulation of lipoprotein lipase (LPL) activity was altered in rats with resistance of glucose metabolism to insulin action induced by a high-fat diet. Relationships between serum insulin and tissue LPL activity were established in rats chronically fed a high-carbohydrate or high-fat diet, and the effects of fasting and intake of meals of habitual and alternate composition were contrasted. The feeding paradigm did not result in the development of obesity. Global resistance of glucose metabolism to insulin brought about by chronic high-fat feeding was confirmed by an intravenous glucose tolerance test. Fasting serum glucose and insulin concentrations were similar in both cohorts, as was LPL activity in retroperitoneal and inguinal white adipose tissues (WAT), the heart, and soleus. A high-carbohydrate meal brought about higher postprandial insulinemia in the cohort chronically fed the high-fat diet. This was associated with larger changes in LPL activity, that is, an increase in inguinal WAT and in brown adipose tissue and a decrease in soleus, red vastus lateralis, and the heart. Thus the established postprandial modulation of LPL, presumably by insulin, was potentiated in the presence of hyperinsulinemia induced by chronic high-fat feeding despite the concomitant impairment of glucose metabolism.