汽油尾气对大鼠睾丸组织的氧化损伤和遗传毒性作用

Effects of the extracts of condensate,particulates and semivolatile organic compounds from gasoline exhaust on oxidative damage and genotoxicity in testicles of rats

目的探讨汽油尾气对大鼠睾丸的遗传毒性及氧化损伤作用。方法将汽油尾气的颗粒物、冷凝物和半挥发性有机物的二氯甲烷提取物以0、5.6、16.7和50.0L/kg的剂量经气管滴注染毒SD大鼠,每周一次,共4次。末次染毒24h后处死动物,测定睾丸脏器系数、睾丸组织内丙二醛(MDA)和羰基蛋白(CP)含量以及超氧化物岐化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)活性;并用彗星实验检测睾丸组织细胞中DNA的单链断裂水平。结果各剂量组体重增重和睾丸脏脏器系数与对照组相比差异无显著性(P>0.05);中、高剂量染毒组睾丸组织中MDA和CP含量显著升高;各剂量组SOD酶活力明显降低(P<0.05),而GSH-Px活性的下降仅在高剂量组具有显著性。在16.7L/kg和50.0L/kg组,睾丸组织细胞的拖尾率较对照组明显增加(P<0.05),但尾长的增加仅在50.0L/kg组具有统计学意义。结论汽油尾气可诱导大鼠睾丸组织生物大分子的氧化损伤和DNA单链断裂。

Objective To determine the effects of the extracts of condensate, particulates and semivolatile organic compounds from gasoline engine exhaust （EGE） on oxidative damage and DNA single strand break in testicles of rats. Methods Rats were exposed to the organic extracts of EGE at the concentrations of 0,5.6,16.7, and 50.0L/ kg body weight via intratracheal instillation, once a week for a month. The body weight and testicle weight were measured, and the contents of malondialdehyde （ MDA ） and carbonyl protein （CP）, and the activities of superoxide dismutase （SOD） and glutathione peroxidase （GSH-Px） in testicles tissue were determined. In addition, the DNA single strand break was examined by comet assay. Results The body weight increment and the absolute and relative weight of the testicles in the group rats treated with various concentrations of EGE were not significant in comparison with those of control group rats. In comparison with the solvent group, the contents of MDA and CP significantly increased at the concentrations of 16.7 and 50.0L/kg EGE（ P 〈 0.05）. On the contrary, the activities of SOD decreased at tested groups （ P 〈 0.05）. But for GSH - Px, the activity reductions were significant only at the concentration of 50.0L/kg EGE（ P 〈 0.05）. In comet assay, at dosesof 16.7 and 50.0L/kg EGE, the rates of tailed cells were （50.06% ± 7.62%） and （83.25%± 8.97%） respectively, the differences were significant in comparison with the solvent group （ P 〈 0.05 ）. However, statistical differences in tail lengths were observed only at the dose of 50.0L/kg EGE in comparison with the controls （ P 〈 0.05）. Conclusion Gasoline engine exhaust could enhance oxidative damage and induce DNA single strand break in testicles of rats.