摘要:
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(50 000 nmol·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-1 PCB118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。
Abstract:
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.
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