【作者】 王广鹤；

【导师】 施华宏； 何德富；

【作者基本信息】 华东师范大学 ， 环境科学， 2010， 硕士

【摘要】 作为一种常见神经退行性疾病,帕金森症(parkinson’s disease, PD)的病因与环境因素关系密切。相关研究显示包括农药在内的多种环境毒物在诱发PD中起一定作用。部分研究已经提及农药百草枯(paraquat, PQ)和鱼藤酮(rotenone, R)与PD发病相关联,但大部分的研究报告出自于流行病学调查,而实验室动物暴露的结果也存在很大不一致性。且以往研究工作主要集中在单种农药神经毒性效应的观察,较少涉及百草枯和鱼藤酮的联合作用的相关研究。考虑到PD病人接触环境毒物的多样性和复杂性,且是一个长期的过程,本文工作选择鱼藤酮、百草枯和代森锰(maneb, MB)三种典型农药,在小鼠上进行低剂量长时间的单独或联合暴露,观察其神经毒性效应对动物运动行为表现的影响,并分析对黑质区域DA能神经元和纹状体区域DA的含量的影响。主要结果如下：1.低剂量的PQ (5mg/kg)、MB (15mg/kg)单独暴露16周后,未引起黑质致密部(SNc)多巴胺(DA)能神经元数量和形态上的病理变化、并未使小鼠纹状体脑区DA含量降低和运动行为的改变。但同样剂量的两者联合暴露8周或16周后,黑质致密部DA能神经元分别缺失25%或40%,且SNc神经元表现出进行性损伤形态。2.较高剂量的PQ (8mg/kg)、鱼藤酮(1.0mg/kg)单独暴露12周后均可导致黑质致密部DA能神经元损伤,SNc细胞损失分别达到26%和15%。PQ暴露神经毒性虽未使纹状体DA含量显著降低,但动物在爬杆上所花时间较对照组显著延长,表明动物运动能力出现一定程度下降。鱼藤酮单独暴露后检测到纹状体DA递质显著较少24%,且动物在开阔试验中跨格次数较对照组显著降低,显示其较强的神经毒性效应。3. PQ (8mg/kg)与鱼藤酮(1.0mg/kg)联合暴露12周,可增强对黑质致密部区域的病理损伤,细胞极显著损失33%,且使纹状体内的DA含量减低达35%,动物在开阔试验中跨格次数较对照组显著降低,而且爬杆时间显著延长。以上结果表明：1.鱼藤酮和PQ均具有明显的诱发PD神经毒性作用,鱼藤酮或PQ暴露可导致小鼠黑质DA能神经元损伤和损失、纹状体DA递质含量降低及动物运动能力减弱。2.PQ的神经毒性表现出一定的剂量-效应关系,并在单独和联合暴露均观察到时间-效应关系。提示诱发PD的环境因素作用可能具有时间剂量阈值。3.PQ和MB、PQ和鱼藤酮均具有协同神经毒性效应,联合暴露对小鼠黑质纹状体系统产生更为严重的影响。研究表明环境中两种或以上的毒物共同作用可能是PD发病的重要诱发因素。本论文工作观察了百草枯、鱼藤酮和代森锰慢性暴露的神经毒性效应,从行为学、病理学和神经化学方面探讨了农药百草枯、鱼藤酮及代森锰与帕金森症发病的关系。实验首先发现百草枯和鱼藤酮联合的低剂量慢性暴露均可诱发动物的类PD运动行为异常,并证实黑质纹状体系统的病理化学改变是其神经毒性作用的机制所在。研究结果将为PD的环境病因学提供重要参考,为相关卫生预防提供依据。更多还原

【Abstract】 As a common neurodegeneration disease, the relationship between the etiology of parkinson’s disease (PD) and environmental factors was extremely closed. The related researches had indicated that environmental toxins, including pesticides, had been playing an important role in inducing the onset of PD. Some studies had involved that paraquat and rotenone are related with the emerging of PD, but most of the results were obtained from epidemiology investigation. At the same time, the results coming from the exposure of experimental animals were not always consistent. Moreover, the previous researches had been mainly focusing on the observations of one single pesticide’s neurotoxicity, less on the combinational effects of paraquat and rotenone. The present research investigated the neurotoxicity produced by three typical pesticides (rotenone, paraquat and maneb) in mice after chronic exposure of any kind of the three pesticides or paraquat combined with maneb or rotenone in low dose. These neurotoxicity investigations in mice include animal behaviors, histopathology of substantia nigra compact, and the dopamine concentration in striatum (CPu).The main results are as follows:1. After alone exposure of lower paraquat (5mg/kg) or maneb(15mg/kg) for 16 weeks, the number and morphology of DA-ergic neurons in SNc area of mice did not change compared to the control animals, animal behaviors and DA concentration in CPu did not change either. However, after combinational exposure of paraquat or maneb with same dosage for 8weeks or 16weeks, DA-ergic neurons in animal SNc lost 25% or 40% respectively, the cell in substantial nigra presented progressive degenation.2. After alone exposure of higher paraquat (8mg/kg) or rotenone (1.0mg/kg) for 12 weeks, it was shown significant lesions of DA-ergic neurons in SNc and significant neural loss of 26% or 15% in SNc respectively. Although the DA concentration in CPu of these paraquat exposure mice do not decline obviously, the time of pole test was prolonged significantly compared with control group, which showed that the locomotory capacity of animals had impaired. The DA concentration in CPu of the rotenone-exposure group decreased by 24%, and the times of crossing grids decreased significantly, all of these could indicate obviously strong neurotoxicity of rotenone.3. Combinational exposure with paraquat (8mg/kg) and rotenone for 12 weeks, could induce mice serious impairments in SNc. Very significant cell loss of 33% was observed in SNc. The DA concentration in CPu decreased by 35% in this group. The results were consistant with behavirol tests, which showed that the times of crossing grids decreased significantly, and the time of pole test prolonged significantly.These results above suggested that:1. Both rotenone and paraquat had the neurotoxicity of inducing PD. Exposure of rotenone or paraquat could result in the impairment or loss of DA-ergic neurons in SNc, the declining of DA concentration in CPu, and the impairment of locomotory capacity.2. The neurotoxicity of paraquat presented the certain degree dose-response relationship. The certain time-response effect could be obsvered in both single or united exposure group. These indicated that the environmental factors could have thresholds of time or dose in inducing PD.3. The synergistic neurotoxicity effects could be observed in either combination of paraquat and maneb, or that of paraquat and rotenone. Their combiational exposure could induce more serious impairment of the SNc-CPu system than the single exposure. It indicated that the cooperation effect of two or more than two kinds of toxicants could be the important inducing factors of PD’s pathogenesis.It was observed the effects of chronic neurotoxiticy effect of paraquat, maneb and rotenone in the present study. The neurotoxicity investigation included ethology, pathology and neurochemistry involved with PD. It was found that paraquat combined choronic exposure with rotenone in low-dose could induce parkinsonism-like behaviors in experimental mice. This behavioral symptom was caused by the pathology changes in SNc-CPu pathway. Our results would provide references for environmental etiology of PD, and provide basis for related hygiene precaution.更多还原