大气污染物SO2、NO2和PM2.5复合暴露诱导大鼠认知功能损伤及其突触标记

Preliminary studies suggest that traffic- and coal industry-related air pollution induced cognitive impairment of exposed population, and the susceptibility varied as function of the age. However, the related data mainly came from epidemiological studies, and evidence supporting the relationship between biomarkers after exposure and cognitive risk in air polluted area was rare. The change of cognitive function not only is the main functional performance of neurological injuries, but also is the early stage of many neurological diseases; whereas synaptic plasticity is attributed to be the biological basis for cognitive activities at cellular level. Therefore, in the present study we will co-expose adult rats to SO2、NO2 via dynamic inhalation and PM2.5 by intratracheal instillation, and will determine the occurrence of cognitive impairment using neurodegeneration assay and behavior test. Following this, we will examine the synaptic responses during cognitive change, by testing electrophysiological function, observing morphology of dendritic spines and applying specific interfering techniques. Based on above results, we will further co-expose rats at differently developmental windows, including descendants at pregnancy and breast-feed stage, young rats, adult rats and senile rats, to SO2、NO2 and PM2.5. Then, we will analyze the difference for inducing cognitive impairment and confine their specific synaptic markers, by determining behavior abnormality, tissue morphology, cellular function and molecular targets. The work is undertaken to set up effective biomarkers for early detection and hazardous assessment of cognition-related neurological diseases in polluted area, and provide experimental evidence for pertinent air pollution control, health risk assesment, as well as prevention and clinical treatment.

交通和煤炭工业源大气污染可能诱导暴露人群的认知功能改变，且存在不同年龄阶段的易感性差异。但相关研究主要集中在流行病学领域，尤其缺乏污染物暴露后生物标志物水平与认知损伤风险相关的证据。认知功能改变是神经系统损伤在功能层面的主要表现，也是多种神经系统疾病的极早期；而突触可塑性则被认为是认知活动在细胞水平的生物学基础。为此，本项目拟通过SO2、NO2动式吸入和PM2.5气管注入建立成年大鼠复合染毒模型，在以神经元退行和学习记忆行为变化为终点确定认知损伤发生的基础上，电生理功能和表观形态检测相结合，辅以特异性干预技术，确立损伤过程的突触响应；进而选择不同生命阶段（孕哺期、幼年、成年和老年）大鼠进行污染物复合暴露，按照整体行为-组织形态-细胞-分子的顺序比较认知损伤差异，并建立相应突触效应标记。本研究旨在建立对污染地区认知损伤进行早期检测和危险度评价的指标，为污染控制、健康风险评估和防护治疗提供依据

大气污染不仅会造成呼吸系统疾病病死率增高，还可能对中枢神经系统产生不良影响，且存在不同年龄阶段的易感性差异。认知功能改变是神经系统损伤在功能层面的主要表现，也是多种神经系统疾病的极早期；而突触可塑性则被认为是认知活动在细胞水平的生物学基础。但相关研究主要集中在流行病学领域，尤其缺乏污染物暴露后生物标志物水平与认知损伤风险相关的证据。为此，本项目拟探讨大气污染物SO2、NO2和PM2.5复合暴露对认知功能的影响，阐明损伤过程的突触响应；在此基础上比较不同生命阶段认知损伤易感性的差异，建立相关分子靶标。主要结果：（1）建立复合暴露体系（C57BL/6J小鼠，SO2、NO2动式吸入6小时/天，PM2.5染毒1次/3天，持续28天），以神经功能变化为终点，结合化学检测和核受体双荧光报告基因、组学等高通量分析，将外暴露污染谱和基于基因组、代谢组等的生物标志物谱有机整合，初步实现关键污染物甄别和毒性通路预测。（2）明确复合暴露剂量依赖性诱导空间学习记忆能力破坏，造成神经元退行性变以及突触结构和功能可塑性变化，主要包括海马区突触密度减少、突触前后膜完整性破坏、突触功能受体表达下调和LTP减少等，在SO2 3.5 mg/m3、NO2 2.5 mg/m3和PM2.5 3.0 g/kg bw浓度组合下与阴性对照组相比出现统计学差异。发现上述效应存在不同生命阶段的易感性差异，幼年小鼠最为敏感，可能与化学组分内暴露特征相关（以金属组分为例分析）。（3）阐明复合暴露诱导空间学习记忆行为变化中BACE1激活参与突触传递的重要作用，揭示神经炎性因子激活NF-κB p65，NF-κB p65与miR-574-5p启动子区的结合下调miR-574-5p表达，miR-574-5p与BACE1 3'UTR区结合反向调控BACE1表达，导致突触可塑性和神经功能损伤的信号过程。通过上述结果，建立对效应进行早期检测和危险度评价的指标，为污染地区污染控制和健康风险评估奠定实验基础；寻求预防和减缓效应发生的最佳时机，为污染地区健康防护和临床治疗提供理论依据。