Role of inflammation in manganese-induced neurotoxicity

描述（由申请人提供） 研究表明，环境污染物，包括锰（Mn），可能有助于特发性帕金森？的疾病（IPD），但这种疾病的病因仍然难以捉摸。在美国，锰污染的两个主要来源是燃料添加剂甲基三羰基锰的重新引入和 含锰杀菌剂（代森锰）。最近，研究人员获得的证据表明，锰，一种神经因子引起帕金森？疾病样症状，通过体外激活的小胶质细胞增加促炎细胞因子和一氧化氮的产生。这些发现表明：（i）炎症在Mn诱导的神经毒性中起作用，（ii）Mn暴露可能是IPD的促成因素（通过增加炎症介质的产生）。这里提出的研究将利用体外和体内方法探索这些可能性。其他研究将开始以描述Mn增强脑中炎症反应的机制。据推测，暴露于Mn增强了小胶质细胞的活化， 不成比例地分布在脑中，结果，发生促炎细胞因子和一氧化氮的过度产生，最终结果是基底神经节中的选择性神经元损失。此外，在炎症刺激的背景下暴露于Mn将增强PD的1-甲基-4-苯基-1，2，3，4-四氢吡啶（MPTP）小鼠模型中的多巴胺能神经元损伤。小胶质细胞系（N9）以及原代小胶质细胞将用于确定Mn形态是否在增加的炎症反应中发挥作用。将在体外研究中使用小胶质细胞（N9）-多巴胺能（PC 12）细胞系共培养物以及中脑原代培养物，并评估在存在小胶质细胞活化剂（内毒素，LPS）的情况下Mn对神经元细胞死亡的影响。此外，将评价Mn对相同体外条件下多巴胺能神经元对MPTP的敏感性的影响。C57 BL/6（MPTP敏感）和CD-1（MPTP抗性）小鼠将用于体内研究，并且动物将与体内研究中的细胞培养物类似地处理。 体外研究。在短时间（14天）暴露于Mn后，将用MPTP激发一些动物，并评估基底神经节损伤的程度以及小胶质细胞活化。成功完成拟议的研究将有助于揭示炎症在锰神经毒性中的作用，更重要的是，建立一种机制，环境污染物可能有助于IPD的病因。拟议的长期目标 研究的目的是了解小胶质细胞和环境污染物在神经退行性疾病中的作用。

DESCRIPTION (provided by applicant) Studies suggest that environmental contaminants, include manganese (Mn), may contribute to Idiopathic Parkinson?s Disease (IPD), but the etiology of this disease still remains elusive. Two major sources of Mn pollution in the United States arise from the reintroduction of the fuel additive methylcyclopentadienyl manganese tricarbonyl and the widespread use of Mn-containing fungicides (maneb). Recently, the investigators obtained evidence that Mn, a neurotokicant causing Parkinson?s Disease-like symptoms, increases proinflammatory cytokines and nitric oxide production by activated microglia in vitro. These findings suggest that (i) inflammation plays a role in Mn-induced neurotoxicity, and (ii) Mn exposure may be a contributing factor (via enhanced production of inflammatory mediators) to IPD. The research proposed here will explore these possibilities utilizing both in vitro and in vivo approaches. Additional studies will begin to delineate the mechanism(s) by, which Mn enhances the inflammatory response in the brain. It is hypothesized that exposure to Mn, enhances activation of microglia which are disproportionately distributed in the brain and as a result, over-production of proinflammatory cytokines and nitric oxide occurs with the final outcome being selective neuronal loss in the basal ganglia. Furthermore, exposure to Mn in the context of an inflammatory stimulus would potentiate the dopaminergic neuronal damage in the 1-methyl-4-phenyl-1,2,3,4- tetrahydropyridline (MPTP) mouse model of PD. Microglial cell line (N9), as well as primary microglia, will be used to determine whether Mn speciation plays a role in the increased inflammatory response. Microglial (N9)-dopaminergic (PC 12) cell line co-cultures, as well as mesencephalic primary cultures will be used in vitro studies and the effects of Mn in the presence of a microglial activator (endotoxin, LPS) on neuronal cell death will be assessed. Additionally, Mn influence on the sensitivity of the dopaminergic neurons to MPTP under the same in vitro conditions will be evaluated. C57BL/6 (MPTP-sensitive) and CD-1 (MPTP-resistant) mice will be used for in vivo studies and animals will be treated similarly to the cell cultures in the in vitro studies. After short (14 days) exposure to Mn, some animals will be challenged with MPTP, and the degree of basal ganglia damage, as well as microglial activation will be assessed. Successful completion of the proposed research will help revealing the role of inflammation in Mn neurotoxicity and, more importantly, establish a mechanism by which environmental contaminants may contribute to the etiology of IPD. The long-term goal of the proposed studies is to understand the role of microglia and environmental contaminants in neurodegenerative diseases.