二氧化硫诱导学习记忆损伤的分子机制及阻断MAGL的保护作用研究

发布时间：2018-06-06 14:29

本文选题：二氧化硫(SO_2) + 空间学习记忆能力　；参考：《山西大学》2015年博士论文

【摘要】：SO2是一种典型的大气污染物,其排放的最大来源是发电厂等工业的化石燃料的燃烧和居民采暖固体燃料的燃烧,主要是煤炭的燃烧。目前,煤炭在我国能源消费中的比例近70%之多。据报道,燃煤大气污染物排放占中国主要能源大气污染物排放总量的七成以上,其中SO2的排放依旧超过烟尘、氮氧化物等其他大气污染物,由此造成的全国城市、工矿区以及居民集区大气SO2污染普遍存在,因此长期接触低浓度SO2所引发的公众健康问题应该受到广泛关注。传统的研究往往更多关注在SO2对呼吸系统的危害；而近年来本课题组的研究发现SO2是一种全身性有毒大气污染物,可通过其衍生物引起多种脏器氧化损伤和DNA损伤。流行病学研究结果显示大气SO2污染和多种神经退行性疾病引起的住院和死亡风险增加具有相关性,比如周期性偏头痛、中风和脑肿瘤等,提示SO2除了能引起我们熟知的呼吸道疾病之外,极有可能是神经系统疾病发病的一个重要诱因。而前期的动物实验研究尚缺乏在神经元突触水平阐释SO2诱导中枢神经损伤的证据；而且众所周知,个体暴露于空气污染的最显著的特征是低浓度终身暴露,而前期的相关研究多集中于流行病学资料或是高浓度SO2吸入暴露,在相对低浓度或低浓度的研究未见报道；尚缺乏直接证据证明人群接触意义低浓度的SO2暴露诱导认知功能损伤。因此本论文通过SO2动式吸入染毒,使用Morris水迷宫检测空间学习记忆能力,通过透射电子显微镜(TEM)观察突触超微结构变化,利用RT-PCR和、Western blot技术检测突触可塑性相关指标在mRNA和蛋白水平的表达改变,使用免疫组织化学切片观察胶质细胞的活化反应,采用酶联免疫技术测定炎症细胞因子的表达,从整体动物行为学、大脑组织病理学和细胞分子生物学多个层面研究了人群接触意义低浓度的SO2污染大气在不同浓度/时程的暴露模型下对大鼠中枢神经系统认知功能和突触信号途径的影响；在此基础上,阐明了MAGL特异性阻断剂JZL184对SO2诱导小鼠神经损伤的影响。研究结果发现,高浓度SO2急性(1 week)暴露可引起大鼠海马组织神经元突轴突末梢小泡密度的增加和突触后密度区的增厚或扩展；上调突触结构标志蛋白SYP和PSD-95的表达,显著下调即早基因Arc和突触受体亚型(GRIA1、GRIA2、 GRIN1、GRIN2A、GRIN2B)的转录水平和相关蛋白激酶(PKA、PKC、p-CaMKIIa)的表达,影响突触信号传递和突触可塑性。低浓度SO2亚慢性(4week)暴露诱导大鼠海马组织和皮层组织神经退行性变和胶质细胞活化反应增加,引起神经炎症反应,导致炎性因子IL-1β、TNF-α和促炎因子COX-2、iNOS的表达显著升高；并能通过引起海马神经元突触前小泡密度减少和突触后密度区变薄以及谷氨酸突触受体亚型和蛋白激酶表达显著降低,改变突触可塑性,最终导致大鼠在Morris水迷宫空间记忆任务中穿越平台区域的次数和在目标象限的时间下降,造成大鼠空间记忆能力损伤。低浓度SO2慢性(90 d)暴露可引起和亚慢性(4 week)暴露相似的结果,通过炎症反应诱导突触可塑性变化并造成空间学习记忆能力损伤。在此基础上,我们发现MAGL特异性阻断剂JZL184预处理能显著减少SO2亚慢性暴露小鼠海马组织和皮层组织神经退行性变和胶质细胞活化反应,维持炎症因子平衡；并能减少神经元突触受体亚型和蛋白激酶表达的下降,保护突触可塑性的完整；提高SO2暴露小鼠的空间记忆能力,显著增加SO2亚慢性暴露小鼠在Morris水迷宫空间记忆任务中穿越平台区域的次数和在目标象限的时间,表明阻断MAGL对SO2诱导小鼠空间记忆损伤和炎症反应具有抑制作用,具有神经保护作用。本课题实验结果系统地揭示了SO2高浓度急性暴露、低浓度亚慢性暴露和低浓度慢性暴露对大鼠大脑中枢神经系统的损伤效应,其分子机制与大脑组织的炎症反应有关,SO2可通过刺激炎症反应改变突触结构和信号传递最终导致学习记忆能力损伤,引发认知功能障碍。这些结果为大气SO2长期低浓度接触和急性污染事件所引发的大脑中枢神经系统损伤提供了实验基础；为大气SO2暴露的健康风险评价提供理论依据。本课题进一步揭示了阻断MAGL在SO2暴露过程中对小鼠的神经保护作用,为SO2污染地区人群神经系统的健康防护提供新思路,并为污染事件发生时的临床治疗提供理论依据。
[Abstract]:SO2 is a typical atmospheric pollutant , the largest source of emission is the combustion of fossil fuels such as power plants and the combustion of the inhabitants ' heating solid fuels , which is mainly the combustion of coal . At present , the emission of coal in China accounts for more than 70 % of the total emission of major energy air pollutants in China .
In recent years , it has been found that SO2 is a kind of systemic toxic atmospheric pollutant , and can cause multiple organ oxidative damage and DNA damage through its derivatives . The epidemiological study shows that the risk of hospitalization and death caused by the pollution of SO 2 and various neurodegenerative diseases is related , such as periodic migraine , stroke and brain tumor .
It is well known that the most significant feature of individual exposure to air pollution is low - concentration lifetime exposure , whereas earlier - related studies focus on epidemiological data or high concentrations of SO2 inhalation exposure , which are not reported at relatively low concentrations or low concentrations ;
The effects of SO 2 on cognitive function and synaptic signal pathway in the central nervous system of rats were studied by means of RT - PCR and Western blot . The effects of SO 2 on the cognitive function and synaptic signal pathway in the central nervous system of rats were studied by means of RT - PCR and Western blot .
On the basis of this , the effects of MAGL specific blocking agent JZL184 on the nerve injury of mice induced by SO2 were elucidated .
Up - regulation of the expression of SYP and PSD - 95 in the synaptic structure indicated that the transcriptional level of early gene Arc and synaptic receptor subtype , and the expression of related protein kinase , protein kinase , PKC , p - CaMKIIa , influenced synaptic transmission and synaptic plasticity . The neuroinflammatory response was induced by low concentration of SO 2 subchronic ( 4week ) exposure , which resulted in increased expression of inflammatory cytokines IL - 1尾 , TNF - 伪 and pro - inflammatory factors COX - 2 and iNOS .
In addition , we found that MAGL - specific blocker JZL184 pretreatment can significantly reduce neurodegeneration and glial activation reaction in hippocampus and cortical tissue of mice with SO2 sub - chronic exposure , and maintain the balance of inflammatory factors .
and can reduce the decrease of neuronal synaptic receptor subtype and protein kinase expression and protect the integrity of synaptic plasticity ;
The results of this study systematically reveal the effects of high concentration of SO _ 2 exposure , low concentration of sub - chronic exposure and low - concentration chronic exposure on the brain central nervous system of rats .
In order to provide a theoretical basis for the assessment of the health risks of SO2 exposure in the atmosphere , this paper further reveals the protective effect of the blocking MAGL on the mice during the process of SO2 exposure , provides a new idea for the health protection of the nervous system of the population in the area of SO2 pollution , and provides a theoretical basis for the clinical treatment when the pollution event occurs .
【学位授予单位】：山西大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：R114

【共引文献】