Insulin induced lipogenesis and enhanced mRNA level of sterol regulatory element binding protein-1c in primary porcine adipocyte

Abstract

Little is known about the development and metabolism of the pig adipocyte, and even less is known about regulation of lipogenesis in the pig adipocyte. The objective of this study was to test the effects of insulin on the morphology of cells, the content of triacylglycerols (TG), the activity of fatty acid synthase (FAS) and the mRNA level of sterol regulatory element binding protein-1c (SREBP-1c) in porcine adipocytes in vitro. Morphologically, larger lipid droplets appeared in the presence of insulin for 48 h. Insulin-induced lipogenesis of primary porcine adipocytes was correlated with the TG content and FAS activity. There was a significant difference in the TG content and FAS activity between the insulin-treated cells and the control cells (P < 0.05); insulin increased the content of TG and FAS activity in a dose-dependent manner and the maximum activity occurred at 150 nmol L-1. The TG content and FAS activity were increased in a dose-dependent manner and maximal values were obtained when adipocytes were incubated with 150 nmol L-1 insulin. The mRNA levels of SREBP-1c were also increased by insulin. In summary, lipogenesis of porcine adipocyte could be induced by insulin in a dose-dependent manner and the induced hypertrophy of porcine adipocytes partially due to the increase of TG content, FAS activity and SREBP-1c mRNA level. Key words: Lipogenesis, porcine, adipocyte, insulin, SREBP-1c