Nutritional regulation of adipose tissue lipoprotein lipase is blunted in insulin resistant rats

Background: Hypertriglyceridemia is a common lipid abnormality accompanying insulin resistance. This study was designed to assess the contribution of dysregulation of adipose tissue lipoprotein lipase (LPL) activity to the hypertriglyceridemia in a rat model of insulin resistance. Methodology: Hereditary hypertriglyceridemic (HHTg) rats were challenged for two weeks on a high sucrose diet and LPL activity, angptl-4 expression and FFA utilisation in vitro were determined in adipose tissue. Results: Compared to control rats (Wistar), HHTg rats exhibited hyperinsulinemia, impaired fatty acid storage in adipose tissue and elevated LPL activity both in fasting and after refeeding. The expression of angiopoietin-like protein 4 (angptl4), a fasting-induced control protein for LPL activity, was not increased in adipose tissue of fasted HHTg rats as it was in the control rats. Conclusion: We conclude that LPL remains in its active form to a higher extent in HHTg rat adipose tissue due to the low expression of angptl4 on fasting. This is a possible consequence of the hyperinsulinemia. In combination with the impaired storage of fatty acids as triglycerides in adipose tissue in HHTg rats, the inflexibility of angptl4 expression may contribute to the establishment of hypertriglyceridemia in the insulin-resistant animals.