多氯联苯暴露对着床期子宫内膜组织中组蛋白甲基化转移酶的影响

Effect of Chronic Exposure to Polychlorinated Biphenyls on the Expression of Histone Methylation Transferase During Implantation Period in CD-1 Mice

目的:探讨多氯联苯(PCB118)慢性暴露对胚胎着床期子宫内膜组织中组蛋白甲基化转移酶的表达影响。方法:将40只CD-1小鼠随机分为4组:空白对照组,1μg/kg PCB118剂量组,10μg/kg PCB118剂量组,100μg/kg PCB118剂量组。灌胃1个月后,促排卵,行雌雄2∶1合笼,次日清晨检查到阴栓记为妊娠第0.5天。于妊娠第4.5天清晨行麻醉,台盼蓝染色观察着床点数量,子宫内膜组织行实时定量RT-qPCR及Western blot检测组蛋白EZH2及MLL1表达量。结果:PCB118慢性暴露后小剂量组和大剂量组小鼠着床个数明显下降(F=32.7,P<0.05)。实时定量PCR结果显示MLL1mRNA表达量在小剂量组及大剂量组明显上调,EZH2的mRNA表达水平未见明显变化。Western blot结果显示,MLL1蛋白表达水平与mRNA水平一致,以小剂量组表达上调最明显。其蛋白表达灰度值依次为120.45±9.87,98.66±6.32,92.33±4.56(F=150.48,P<0.01)。EZH2的蛋白表达水平未见明显变化。蛋白表达灰度值依次为92.73±5.98,96.32±7.34,90.92±5.76(F=1.32,P>0.05)。结论:孕前PCB118慢性暴露可干扰早期妊娠进行,影响胚胎着床,着床期组蛋白甲基化转移酶MLL1的表达也受到影响。

Objective：To study the effect of polychlorinated biphenyls on the expression of histone methylation transferases.Methods：Virgin CD-1female mice（3-week old）were housed and orally treated with PCB 118（0,1,10,100μg/kg）for a month.After mating with fertile males,the pregnant mice were sacrificed on gestation D4.5.Trypan blue was used to detect the implantation sites.Real-time PCR and Western blot were conducted to measure the expression of histone methylation transferase EZH2 and MLL1.Results：Compared with the control group,implantation failures were observed in 1μg/kg PCB118 and 100μg/kg PCB118 treated groups（F=32.7,P〈0.05）.Real-time QPCR detected no change in the mRNA level of EZH2,but showed high mRNA expression level of MLL1.The grey value of EZH2 was 92.73±5.98,96.32±7.34,and 90.92±5.76 in turn.The grey value of MLL1 was 120.45±9.87,98.66±6.32,and 92.33±4.56 in turn.Conclusion：Chronic PCB118 exposure has a bad effect on embryo implantation,and may affect histone modification through regulating the expression of histone methylation transferase MLL1.