Inhibition of SOCS-3 in adipocytes of rats with diet-induced obesity increases leptin-mediated fatty acid oxidation.

Rats with diet-induced obesity (DIO) usually experience hyperleptinemia. Thus, leptin produced by adipocytes does not deplete adipocyte fat, which implying a leptin resistance in adipocytes during overnutrition. Here, we induced hyperleptinemia in rats by feeding them a diet consisting of 45% fat. In epididymal adipose tissues, the mRNA and protein levels of a putative leptin resistant factor, suppressor of cytokine signaling 3 (SOCS-3), were increased. The mRNA levels of SOCS-3 in adipocytes differentiated from adipose-derived stromal cells (ADSCs) were higher in DIO rats than in rats on a 10% fat diet. Using SOCS-3 short hairpin RNA lentivirus interference, we found decreased expression of acetyl-CoA carboxylase mRNA (a marker of de novo lipogenesis) and increased expression of acetyl-CoA oxidase mRNA (a marker of fat oxidation) in SOCS-3-knockdown adipocytes after incubation with 50 nM leptin for 6 h. We conclude that the SOCS-3 knockdown may have increased the leptin-mediated in situ fatty acid oxidation in the DIO adipocytes, and therefore, SOCS-3 might be an excellent target for therapeutic intervention for obesity.