Effects of Leptin on Porcine Primary Adipocytes Lipolysis and mRNA Expression of Key Lipolytic Enzymes

Leptin as a cytokine predominantly secreted by fat tissue plays an important role in regulating organism energy balance. Leptin can stimulate lipolysis, but the mechanism is not clear. In order to research the molecular mechanism of Leptin stimulating lipolysis, the present study systematically investigates the mRNA expression of key lipolytic enzymes. Morphological observation, Oil Red O staining, and RT-PCR were used to identify the pig primary adipocytes; commercial kits were used to measure the glycerol and FFA release; Semiquantitative RT-PCR was used to detect the mRNA expression of key lipolytic enzymes. The results showed that 100 nM Leptin up-regulates the mRNA expression of ATGL, TGH-2, HSL, MGL, and LPL (P < 0.01), whereas it down-regulates the Perilipin mRNA expression (P < 0.01); at the same time, Leptin promotes the glycerol release in a dose dependent manner (P < 0.01) but has no effect on the FFA release (P > 0.05). These indicate that Leptin may mainly stimulate lipolysis in pig primary adipocytes by up-regulating the expression of ATGL, MGL, LPL, and down-regulating the expression of Perilipin; and the unchanged FFA release may be resulted from Leptin promoting UCPs mRNA expression and increasing FFA expenditure.