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

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(0.05～50 000 nmol·L-1)分别作用GT1-7细胞6、12、24和48 h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(50 000nmol·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6 h后,5、500和50 000 nmol·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24 h,500和50 000 nmol·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。

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

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, decreased 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.