PCB118对GT1-7细胞GnRH分泌及Kisspeptin/GPR54信号通路蛋白表达的影响

Effects of PCB118 on GnRH Secretion and Proteins Expression of Kisspeptin/GPR54 Signaling Pathway in GT1-7 Cells

为研究多氯联苯118(polychlorinated biphenyl 118,PCB118)对GT1-7细胞的毒性作用,探讨其对促性腺激素释放激素(gonadotropin-releasing hormone,GnRH)分泌的影响及相关机制,在PCB118作用GT1-7细胞后,分析了细胞存活率、GnRH分泌水平以及Kisspeptin/GPR54信号通路中关键蛋白的表达水平。结果表明,PCB118(0.05~50000nmol·L^-1)分别作用GT1-7细胞6、12、24和48h后,细胞存活率随PCB118浓度的增加和作用时间的延长而显著降低。但只有在高浓度(50000nmol·L^-1)条件下,PCB118才能显著促进GT1-7细胞释放乳酸脱氢酶(lactate dehydrogenase,LDH)。PCB118作用GT1-7细胞6h后,5、500和50000nmol·L^-1组能显著抑制GnRH的分泌,并降低Kisspeptin/GPR54信号通路中GnRH、G蛋白偶联受体54(G-protein-coupled receptor 54,GPR54)、磷脂酶C(phospholipase C,PLC)和蛋白激酶C(protein kinase C,PKC)等关键蛋白的表达水平;作用24h,500和50000nmol·L^-1PCB118能显著抑制GnRH的分泌,并降低GnRH、GPR54、PLC和PKC等关键蛋白的表达水平。研究表明:PCB118对GT1-7细胞具有细胞增殖毒性作用,呈现一定的剂量和时间效应;PCB118能在一定程度上抑制GT1-7细胞GnRH的合成与分泌,并下调Kisspeptin/GPR54信号通路中GnRH、GPR54、PLC和PKC等关键蛋白的表达水平,推测Kisspeptin/GPR54信号通路可能参与介导了PCB118对GT1-7细胞GnRH分泌的抑制作用。

To explore the underlying mechanism of dioxin-like polychlorinated biphenyl 118 (PCB118) on the secretion of gonadotropin-releasing hormone (GnRH),GT1-7 cells were exposed to different concentrations of PCB118.Cell viability,release of GnRH and expression of associated proteins in Kisspeptin/GPR54 signaling pathway were investigated.The results showed that PCB118 (0.05-50 000 nmol·L^-1 ) significantly reduced cell viability of GT1-7 cells in dose- and time-dependent manners after exposure for 6 h,12 h,24 h and 48 h.Interestingly,de creased release of lactate dehydrogenase (LDH) was only observed under the treatment of 50 000 nmol·L^-1 PCB118.Exposure to 5,500 and 50 000 nmol·L^-1 PCB118 for 6 h significantly decreased the levels of GnRH in the culture media with significant down expression of proteins in Kisspeptin/GPR54 signaling pathway,including GnRH,GPR54,PLC and PKC in GT1-7 cells.Similarly,significantly-decreased GnRH levels and down regulation of such proteins were observed after exposure to 500 or 50 000 nmol·L^-1 PCB118 for 24 h.Taken together, PCB118 shows cytotoxic effects on GT1-7 cells in dose- and time-dependent manners.These results indicate that PCB118 might affect the secretion of GnRH through inhibiting the expression of associated proteins in Kisspeptin/ GPR54 signaling pathway.