The function of porcine PPARγ and dietary fish oil effect on the expression of lipid and glucose metabolism related genes

Peroxisome-proliferator-activated receptor gamma (PPAR gamma) plays a critical role in regulation of adipocyte differentiation and insulin sensitivity. To become functional, PPAR gamma must be activated by binding an appropriate ligand. Polyunsaturated fatty acids (PUFA) are potential ligands for PPAR gamma. The current experiment was designed to determine the potential for PUFA, particularly eicosapentaenoic acid and docosahexaenoic acid, to activate the function of porcine PPAR gamma in vivo. Transgenic mice, expressing porcine PPAR gamma in skeletal muscle were generated and fed with a high-saturated fat (beef tallow) or high-unsaturated fat (fish oil) diet for 4 months. When transgenic mice were fed a fish oil supplemented diet, the expression of adipogenic and glucose uptake genes was increased, leading to reduced plasma glucose concentration. The PPAR gamma transgene increased the expression of Glut4 in the muscle. This result suggests that there was increased glucose utilization and, therefore, a reduced blood glucose concentration in the transgenic mice. Also, the plasma adiponectin was elevated by fish oil treatment, suggesting a role of adiponectin in mediating the PUFA effect These results suggest that PUFA may serve as a natural regulator of glucose uptake in vivo and these effects are mainly through PPAR gamma function. (C) 2011 Elsevier Inc. All rights reserved.