4-溴联苯醚对大鼠睾丸γH2AX表达的影响

Impact of 4-bromobiphenyl ether on the expression ofγH2AX in the rat testis

目的:分析4-溴联苯醚(4-BDE)对大鼠睾丸组织γH2AX表达的影响,进而探索4-BDE对雄性大鼠生殖功能影响及可能的机制。方法:SD雄性大鼠24只,随机分为4组:对照组,50、100、200mg/kg 4-BDE染毒组;对照组灌胃同等量的橄榄油,每天灌胃1次,连续30 d。大鼠处死后取睾丸进行HE染色,TUNEL法检测细胞凋亡,qPCR检测H2AX、Western印迹检测γH2AX表达情况。结果:与对照组相比,100、200mg/kg染毒组光镜下偶见生精小管内精原细胞、支持细胞减少或缺失。TUNEL结果显示与对照组相比,各染毒组大鼠睾丸组织凋亡指数明显增高,且随染毒剂量的增高凋亡指数呈上升趋势,差异有统计学意义(P<0.05);与50 mg/kg染毒组相比,100、200 mg/kg染毒组凋亡指数明显增高,差异有统计学意义(P<0.05),存在剂量-效应关系,但100 mg/kg染毒组与200 mg/kg染毒组相比差异无统计学意义(P>0.05)。与对照组相比,各染毒组H2AX mRNA表达水平差异无统计学意义(P>0.05);各染毒组之间比较差异也无统计学意义(P>0.05)。Western印迹结果显示,与对照组相比,染毒组γH2AX蛋白表达量明显升高,差异有统计学意义(P<0.05),各染毒组间比较差异无统计学意义(P>0.05)。结论:100、200 mg/kg 4-BDE染毒组大鼠睾丸组织内生精小管结构受损,染毒组睾丸组织内细胞凋亡均增加,γH2AX蛋白表达明显升高,DNA双链断裂(DSB)增多,细胞的凋亡可能与DSB有关。

Objective:To investigate the effects of monobromobiphenyl ether(4-BDE)on the expression ofγH2AX in the rat testis,and the possible mechanism of 4-BDE affecting the reproductive function of the male rats.Methods:Twenty-four SD male rats were randomly divided into 4 groups:control and low-,medium-and high-dose 4-BDE,the control rats treated intragastrically with olive oil,and the animals in the latter three groups with 4-BDE at 50,100 and 200 mg/kg/d,respectively,all for 30 consecutive days.Then all the rats were killed and the testis tissues harvested for HE staining,examination of the apoptosis of the cells by TUNEL and determination of the expressions of H2 AX mRNA andγH2AX by q-PCR and Western blot.Results:HE staining manifested occasional reduction or absence of spermatogonial and Sertoli cells in the seminiferous tubules in the medium-and high-dose 4-BDE groups.Compared with the controls,the rats exposed to 4-BDE showed a significant dose-dependent increase in the apoptosis of the testis tissue(P<0.05),even more significant in the medium-and high-dose 4-BDE groups than in the low-dose group(P<0.05).There was a dose-effect relationship in the apoptosis index,but with no statistically significant difference between the medium-and high-dose 4-BDE groups(P>0.05).The results of q-PCR exhibited no statistically significant difference in the expression level of H2 AX mRNA either between the control and 4-BDE-exposed rats(P>0.05)or among the three 4-BDE groups(P>0.05).The expression of theγH2AX protein was remarkably higher in the 4-BDE groups than in the control(P<0.05),but not significantly different among the 4-BDE groups(P>0.05).Conclusion:Exposure to 4-BDE at 100 or 200 mg/kg/d damages the structure of seminiferous tubules,increases the apoptosis of testicular cells,significantly up-regulates the expression of theγH2AX protein,and consequently increases DNA double-strand breaks(DSB)in the rat testis.The apoptosis of testicular cells may be related to DSB.