黑碳和臭氧处理的黑碳对小鼠遗传损伤的比较研究

Comparison of genetic damage in mice exposed to black carbon and ozone-oxidized black carbon

目的:评价大气黑碳(black carbon,BC)与臭氧处理黑碳(ozonized black carbon,O3-BC)对机体的遗传毒性,并从氧化应激的角度探讨其机制。方法:将74只体重为(28.0±1.5)g的雄性ICR小鼠随机分为7组,即磷酸盐缓冲液对照组和两种颗粒物的50μg、100μg、200μg混悬液滴注组(每次每只动物分别滴注50、100、200μg)。最高剂量组(200μg组)为12只,其余组均为10只。染毒为每天气管滴注1次,连续滴注4天,末次染毒24 h后处死动物。测定血清过氧化氢酶(catalase,CAT)活性、肺匀浆丙二醛(malondialdehyde,MDA)含量、血清及随机尿8-羟基脱氧鸟苷(8-hydroxyguanosine,8-OHdG)水平,对骨髓涂片进行微核计数及肺组织病理分析。结果:小鼠一般情况良好,与对照组相比染毒组肝脏器系数降低(P<0.05);100μg和200μg两种颗粒物组血清CAT活性较对照组增加(P<0.05),微核率亦较对照组增加(P<0.05);各组血清及尿中8-OHdG和肺匀浆MDA差异无统计学意义;组织病理观察,暴露于颗粒物后肺组织出现炎症反应。结论:急性暴露于高剂量BC及O3-BC的小鼠体内氧化应激水平升高,并出现遗传损伤,但两种颗粒物毒性无明显差异,O3处理是否增加BC的遗传毒性还有待于进一步探讨。

Objective：To make an assessment on the genotoxicity caused by black carbon （ BC ） and ozonized black carbon （O3-BC）.Methods： In this study, 74 healthy male ICR mice [weighed （28 ± 1.5） g] were randomly divided into 7 groups, including one phosphate buffer solution （ PBS） control group and six particles exposed groups by intratracheal instillation with either BC or O 3-BC at the doses of 50, 100, 200 μg/mouse, respectively.There were 12 mice in the groups of 200μg/mouse and 10 mice in others.The mice were sacrificed 24 h after four intratrachealinstillations .The activities of catalase （ CAT） in serum and the levels of malondialdehyde （ MDA） in lung tissue homogenate were measured . As the DNA damage mark , 8-hydroxyguanosine （ 8-OHdG ） in urine and serum were quantified with ELISA method.Micronucleus test was used for potential genotoxicity of BC and O 3-BC.Hematoxylin and eosin staining was used to stain lung paraffin section .Results：The mice were in good condition during instillation , and the liver coefficient of the test groups was significantly lower than that of the control group （P〈0.05）.The activities of CAT in serum significantly increased in the 100 μg/mouse and 200μg/mouse groups after being exposed to these two kinds of particles .The micronucleus rate in allthe BC and O3-BC exposed groups increased （ P 〈0.05）, but there was no statistically significant difference among the groups in the levels of 8-OHdG in serum and urine and MDA in lung tissue homogenate .In-flammatory response was found in the lung tissue under the microscope after exposure to BC and O 3-BC. Conclusion：Intratracheal instillation of BC and O 3-BC induced increasing of oxidative stress and genetic damage in mice .But there was no significant difference between these two particles in toxicity .Whether the genotoxicity of O 3-BC is higher than that of BC or not is uncertain .Further research is needed .