Palmitic Acid Affects Lipid Accumulation In Ovarian Granulosa Cells Via PPAR? Regulation Of SR-BI

Background:Polycystic ovary syndrome?PCOS?is among the most common metabolic disease in women of reproductive age,which features consist of oligo/anovulation,hyperandrogenism with clinical or biochemical symptoms and presence of polycystic ovaries.According to studies,approximately 80%of PCOS patients exhibit abnormal serum lipid levels.A high level of palmitic acid?PA?is found in the blood and follicular fluid of patients with PCOS,and PA is associated with granulosa cell lipid toxicity,but whether it promotes granulosa cell lipid accumulation is not clear.Scavenger receptor BI?SR-BI?is a membrane receptor on cell membrane and is mainly involved in lipid transport.The study found that the change of SR-BI expression contributed to the female infertility.Moreover,studies have shown that PPAR?regulates SR-BI expression in hepatocytes,however,the effect of SR-BI/PPAR?in KGN cells abnormal lipid metabolism is not clear.Objective:The aim of this study is to explore the mechanism of palmitic acid regulating the expression of SR-BI via PPAR?in lipid accumulation of KGN cells.Method:KGN cells were grown in DMEM medium supplemented with 10%fetal bovine serum at 37°C,5%CO₂.1)The cells were incubated with palmitic acid?0,100,200,300 umol/ml?for 24 hours.Cellular lipid droplet was measured by Oil Red O staining,intracellular lipid content was detected by NBD-Cholesterol fluorescence labeling.The expression of SR-BI and peroxisome proliferators-activated receptor??PPAR??was examined by immunocytochemistry,immunofluorescence and western blotting;2)Cellular lipid droplet was measured by Oil Red O staining,intracellular lipid content was detected by NBD-Cholesterol fluorescence labeling after intervening the expression of SR-BI in KGN cells.3)Oil Red O staining was performed to analyze the lipid content in KGN cells,and immunocytochemistry,immunofluorescence and western blotting were performed to analyze the expression of SR-BI after intervening the expression of PPAR?.Results:1)After treating with different concentrations of palmitic acid,a increase of the lipid content was appeared with concentration-dependent manner in KGN cells compared to the control group;Compared to the control group,the expression of SR-BI was significantly up-regulated with concentration-dependent manner?P<0.05?;Compared to the control group,the expression of PPAR?was significantly up-regulated in 200,300?mol/L palmitic acid group?P<0.05?.2)After treating with BLT-1?a SR-BI inhibitor?,compared to the control group,a increase of the lipid content in palmitic acid group,compared to palmitic acid group,a decrease of the lipid content in palmitic acid co-incubated with BLT-1 group.3)After treating with GW6471?a PPAR?inhibitor?,a increased of the lipid content in palmitic acid group compared with the control group,compared to palmitic acid group,a decrease of the lipid content in palmitic acid co-incubated with GW6471;Compared to the control group,the expression of SR-BI was up-regulated?P<0.05?in palmitic acid group,compared to palmitic acid group,the expression of SR-BI was down-regulated in palmitic acid co-incubated with GW6471?P<0.05?.Conclusion:1.Palmitic acid promotes lipid accumulation in human ovarian granulosa cells.2.Palmitic acid regulates the expression of SR-BI by PPAR?to affect lipid accumulation in human ovarian granulosa cells.