大气细颗粒物PM2.5对大鼠神经损伤机制的研究

With the rapid development of modern industry, air pollution has been exploding in the past decades, and consequently resulted in more and more damage to the human body. Air pollution especially fine particulate matter (PM2.5）has become the major evaluation of urban air quality. It has been reported that long-term exposure or acute exposure to the pollution matters could directly or indirectly cause a variety of cardiovascular and cerebrovascular damage ,including damage to the central nervous system (CNS) may lead to the occurrence of neurodegenerative diseases, such as Alzheimer’s disease, but the mechanism of the nervous system injury caused by fine particulate matter (PM2.5) in the atmosphere still remain largely elusive. In present study, we will investigate the differences in nature and major components of PM2.5 collected by air sampling in the urban area in Changchun, and analyze the major components which induced nerve cell damage animal and cellular experiments. RTFQ-PCR, Western blot and immunohistochemical technique was taken out to investigate the changes in the expression level of PP2A and Caspase-3 and phosphorylation of Tau,. The results will illustrate the mechanism of rat’s nerve injury induced by PM2.5 and would be helpful to understanding the effects of air Particulate matter on human health.

随着现代社会工业的发展，空气污染日益严重，其对人体的损害也越来越大。空气污染特别是大气中细颗粒物PM2.5，已成为我国各大城市环境空气质量的评价指标。研究表明，长期或急性暴露在空气污染物中可直接或间接导致各种心脑血管损伤，其中对中枢神经系统的损伤可导致阿尔茨海默病的发生，但细颗粒物对神经系统的损伤机制尚未阐明。本研究以空气细颗粒物PM2.5作为切入点，检测长春市区PM2.5中主要成分的含量及种类，通过体外细胞实验和动物实验确定PM2.5中致神经细胞损伤的主要成分，并通过荧光定量PCR、western blot和免疫组化分析这些成分对神经细胞中Tau蛋白磷酸化程度的影响以及对PP-2A和caspase3 等蛋白表达的影响，从分子、细胞和动物体水平对PM2.5致神经损伤的毒理学机制进行分析，从而阐明PM2.5对大鼠神经损伤机制。研究结果将为细颗粒物污染的防治、有效地保护人类健康提供理论依据。

随着现代社会工业的发展，空气污染日益严重，其对人体的损害也越来越大。空气污染别是大气中细颗粒物PM2.5，已成为我国各大城市环境空气质量的评价指标。研究表明，长期或急性暴露在空气污染物中可直接或间接导致各种心脑血管损伤，其中对中枢神经系统的损伤可导致阿尔茨海默病的发生，但细颗粒物对神经系统的损伤机制尚未阐明。本研究检测了长春市区PM2.5中金属离子和有机成分的含量，结果显示各种重金属含量分别为：铜（Cu）0.06%，铁（Fe）28.52%，锰（Mn）1.06%，铅（Pb）0.38%，铬（Cr）0.04%，镉（Cd）0.0087%。PM2.5共检出15种3类化合物，包括苯系物、醛、脂肪烃，PM2.5中脂肪烃(种)相对百分含量为28.48%、苯系物(种)相对百分含量为45.99%、醛类(种)相对百分含量为13.81%，结果表明，PM2.5上吸附有毒性较大的有机组分，能够对机体造成伤害。对其尿液的代谢组学进行了检测，通过超高效液相色谱与四极飞行时间质谱联用（UPLC-Q-TOF-MS）法从大鼠尿样中鉴定出17种潜在生物标记物。主要代谢途径涉及戊糖和葡萄糖醛酸盐相互转化，淀粉和蔗糖代谢，色氨酸代谢，酪氨酸代谢，苯丙氨酸代谢，嘌呤代谢，对乙酰氨基酚代谢途径，视黄醇代谢和丙戊酸代谢途径。采用LC-MS检测大鼠脑内单胺类神经递质及其代谢产物浓度的变化PM2.5处理组大鼠海马区Tau 和Ach 的水平显著降低( P＜0.01), Glu，Asp，Ser，GABA，DA 以及5-HT 水平显著升高( P＜0.01，且随着PM2.5剂量的增加有递增的趋势，具有剂量依赖性。细胞毒理学研究结果表明PM2.5处理后RAW264.7会增加LDH的漏出、引起胞内Ca2+超载，S期细胞比例下降显著，可刺激RAW264.7细胞产生过量的ROS，促进细胞验证因子TNF-α和IL-6的释放，致Bax/Bcl-2比值升高, NF-κB、MyD88蛋白水平明显上升, DAT、TH蛋白表达量显著下降，而α-synuclein蛋白水平显著上升。表明PM2.5致神经损伤的机理可能与NF-κB /TRL4 /MyD88炎症信号通路相关。本研究结果从分子、细胞和动物体水平对PM2.5致神经损伤的毒理学机制进行分析，从而阐明PM2.5对大鼠神经损伤机制。研究结果将为细颗粒物污染的防治、有效地保护人类健康提供理论依据。