Regulation and mechanism of leptin on lipid metabolism in ovarian follicle cells from yellow catfish Pelteobagrus fulvidraco

The present study was conducted to determine the effect of leptin on lipid metabolism in ovarian follicle cells of yellow catfish Pelteobagrus fulvidraco. For that purpose, primary ovarian follicle cells were isolated from yellow catfish, cultured and subjected to different treatments (control, 0.1% DMSO, 500 ng/ml leptin, 500 ng/ml leptin plus 100 μM wortmannin, 500 ng/ml leptin plus 50 nM AG490, respectively) for 48 h. Intracellular triglyceride (TG) content, the activities (CPT I, FAS, G6PD, and 6PGD) and/or expression level of several enzymes (CPT I, FAS, G6PD, 6PGD, ACCa and ACCb), as well as the mRNA expression of transcription factors (PPARα, PPARγ and SREBP-1) involved in lipid metabolism were determined. Recombinant human leptin (rt-hLEP) incubation significantly reduced intracellular TG content, activities and mRNA levels of FAS, G6PD and 6PGD, SREBP-1 and PPARγ, but enhanced activity and mRNA level of CPT I, PPARα and ACCa. Specific inhibitors AG490 and wortmannin of JAK-STAT and IRS-PI3K signaling pathways prevented leptin-induced changes, indicating that JAK-STAT and IRS-PI3K signaling pathways were involved in the process of leptin-induced changes of lipid metabolism. Based on these observations above, for the first time, our study indicated that leptin reduced lipid deposition by activating lipolysis and suppressing lipogenesis in ovarian follicles of yellow catfish, and both JAK-STAT and IRS-PI3K signaling pathways were involved in the changes of leptin-induced lipid metabolism.