Manganese and basal ganglia dysfunction: role of NO

描述（由申请人提供）：锰（Mn）慢性中毒是一种退行性运动障碍的原因，称为锰中毒，其临床特征类似于帕金森病。最近的研究结果表明，对大脑这一区域的损伤涉及到神经胶质细胞正常支持功能的扰动，导致炎症基因的表达增加，如诱导型一氧化氮合酶（NOS2），随后可产生神经毒性水平的一氧化氮（NO）。类似的有害神经胶质相互作用发生在基底神经节的其他退行性疾病中，如帕金森氏症和亨廷顿氏病，强调需要阐明这些破坏性相互作用的机制。本研究计划的长期目标是更好地了解神经胶质细胞在基底神经节疾病发病机制中的作用。本应用程序的目的是确定在锰的实验模型胶质介导的神经元损伤的机制。核心假设是Mn暴露导致神经胶质激活和NOS2的表达，NOS2通过过量产生NO导致年龄依赖性神经元损伤和基底神经节功能衰弱。这一假设将通过追求两个特定目标来验证：1)确定在星形胶质细胞中引起NOS2诱导的mn依赖信号。这一目标的工作假设是Mn通过激活特定的MAP激酶来增加nf - kappab依赖性NOS2的表达。2)确定基底神经节对锰的年龄依赖性易感性的机制。在这一目的下，假设在发育过程中mn介导的NO的产生导致胶质细胞激活和神经元损伤，从而降低随后暴露后基底神经节功能障碍的阈值。该实验方法利用NF-KappaB通路中特定信号分子的遗传阻断来鉴定星形胶质细胞中NOS2表达的关键上游激活因子。在暴露于Mn的新生、成年野生型和转基因小鼠中，将对鉴定出的因子活性与NF-KappaB活性和NOS2表达的关系进行量化。预计这种创新的方法将通过增加NO的合成来识别Mn促进神经元损伤的重要早期靶点。这项研究具有重要意义，因为它有望促进对基底神经节疾病中神经胶质源性NO的致病作用的理解，从而促进针对神经胶质细胞炎症信号通路的神经保护治疗策略的发展。

DESCRIPTION (provided by applicant): Chronic intoxication with manganese (Mn) is the cause of a degenerative movement disorder, termed manganism, with clinical features that resemble Parkinson's disease. Recent findings suggest that injury to this region of the brain involves perturbation of the normally supportive function of glial cells to an activated state that results in increased expression of inflammatory genes such as inducible nitric oxide synthase (NOS2), that can subsequently produce neurotoxic levels of nitric oxide (NO). Similar deleterious neuro-glial interactions occur in other degenerative disorders of the basal ganglia, such as Parkinson's and Huntington's diseases, highlighting the need to elucidate the mechanisms underlying these damaging interactions. The long-term goal of this research program is to better understand role of glial cells in the pathogenesis of diseases of the basal ganglia. The objective of this application is to identify mechanisms underlying glial-mediated neuronal injury in an experimental model of manganism. The central hypothesis is that Mn exposure results in glial activation and expression of NOS2 that contributes to age-dependent neuronal injury and debilitation of basal ganglia function through overproduction of NO. This hypothesis will be tested by pursuing two specific aims: 1) Determine the Mn-dependent signals that cause induction of NOS2 in astroglial cells. The working hypothesis for this aim is that Mn increases NF-KappaB-dependent expression of NOS2 by activating specific MAP kinases. 2) Identify the mechanisms underlying age-dependent susceptibility of the basal ganglia to manganese. It is postulated under this aim that Mn-mediated production of NO during development results in glial activation and neuronal injury that decreases the threshold for basal ganglia dysfunction upon subsequent exposures. The experimental approach proposed utilizes genetic interdiction of specific signaling molecules in the NF-KappaB pathway to identify critical upstream activators of NOS2 expression in astroglial cells. The activity of the factors identified will be quantified in relation to activity of NF-KappaB and expression of NOS2 in neonatal and adult wildtype and transgenic mice exposed to Mn. It is expected that this innovative approach will identify important early targets of Mn that promote neuronal injury by increased synthesis of NO. The proposed research is significant, because it is expected to advance understanding of the pathogenic role of glial-derived NO in disorders of the basal ganglia and, thereby, to foster the development of neuroprotective therapeutic strategies that target inflammatory signaling pathways in glial cells.