柴油尾气颗粒对秀丽隐杆线虫慢性毒性效应的初步研究

Preliminary Study on the Chronic Toxicity of Diesel Exhaust Particles on Caenorhabditis elegans

柴油机尾气颗粒(diesel exhaust particles,DEP)对PM2.5有重要贡献,已有研究发现其与暴露人群的肺癌、慢性支气管疾病、心血管疾病等密切相关。以DEP为研究对象,以秀丽隐杆线虫(Caenorhabditis elegans)为模式生物,观察了柴油机尾气颗粒在线虫体内的分布情况,并以线虫头部摆动频率、体长体宽、活性氧自由基(ROS)水平、细胞凋亡水平、脂褐素水平为评价指标探究了DEP暴露对线虫的慢性毒性效应。结果表明,经过10 d的慢性暴露,1 mg·L^−1的DEP明显富集在线虫的咽部和肠道,中低浓度的(0.001、0.01、0.1 mg·L^−1)DEP未出现明显的体内富集现象。随着浓度的增加,线虫的头部摆动频率、体长和体宽均呈先上升后降低的趋势,差异具有统计学意义(P<0.01)。中浓度组(0.1 mg·L^−1)线虫体内ROS水平和细胞凋亡水平较对照组均有所降低,而高浓度(1 mg·L^−1)的DEP显著提高了线虫体内的ROS水平和细胞凋亡水平(P<0.05)。中高浓度的DEP均能使线虫肠道脂褐素积累升高(P<0.05)。研究揭示了DEP具有在生物组织体内富集的特点,长期积累会影响其运动行为,抑制其生长发育,导致其体内ROS水平和细胞凋亡升高并使肠道老化,具有潜在的神经和发育毒性效应。研究结果可为DEP的人群暴露的慢性毒性评价提供理论参考。

Diesel exhaust particles(DEP),the main contributor of PM2.5,has been confirmed to be closely related to lung cancer,chronic bronchial diseases and cardiovascular diseases.In the present study,the chronic toxicology of DEP in environmental concentrations was explored by using biochemical indicators of Caenorhabditis elegans,including the distribution of DEP in vivo,head thrash frequency,developmental conditions,reactive oxygen substance(ROS)level,apoptosis level and lipofuscin level.The results showed that DEP at the dose of 1 mg·L^−1 was significantly enriched in the pharynx and intestine of nematodes after 10 days of chronic exposure,while DEP at low medium concentrations(0.001,0.01,0.1 mg·L^−1)did not displayed such significant enrichment.Additionally,the head thrash frequency,body length and body width of the nematode increased significantly at the concentrations of DEP ranging from 0.001 to 0.1 mg·L^−1,and decreased at the maximum concentration using in this study(P<0.01).Furthermore,the ROS level and apoptosis level were reduced compared with that of the control group in the concentration of 0.1 mg·L^−1,while high concentration of DEP(1 mg·L^−1)significantly increased the ROS level and apoptosis level(P<0.05).Simultaneously,medium and high concentration of DEP could increase the accumulation of lipofuscin in the intestine of C.elegans(P<0.05).This study revealed that high concentration of DEP possessed the characteristics of enrichment in biological tissue.Long-term accumulation of DEP could affect worm’s movement and development,increase the level of ROS and cell apoptosis in vivo,and accelerate intestinal aging,which indicated that DEP had potential to influence neurogenic and developmental toxicity effects.This result can provide a theoretical reference for the evaluation of chronic toxicity of DEP.