Environmental Toxicants and Neurodegeneration

环境毒物和神经退行性疾病

基本信息

批准号：
7270655
负责人：
KIM TIEU
金额：
$ 32.38万
依托单位：
UNIVERSITY OF ROCHESTER
依托单位国家：
美国
项目类别：
财政年份：
2006
资助国家：
美国
起止时间：
2006-08-01 至 2011-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7270655
关键词：
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine 1-Methyl-4-phenylpyridinium Ablation Affect Animal Model Astrocytes Attenuated Biomedical Research Brain Categories Cations Cell Death Cell membrane Cells Cessation of life Chemicals Coculture Techniques Corpus striatum structure Cultured Cells Data Dopamine Drug Kinetics Extracellular Space Goals Herbicides Injection of therapeutic agent Investigation Kinetics Learning Link Microdialysis Midbrain structure Modeling Molecular Mus Mutant Strains Mice Nerve Degeneration Neurodegenerative Disorders Neurons Neurotoxins Organic Cation Transporter Paraquat Parkinson Disease Parkinsonian Disorders Pathway interactions Pattern Predisposition Protein Overexpression Research Personnel Role Site Substantia nigra structure Testing Time Tissues Toxic Environmental Substances Toxic effect Toxicokinetics base cell type density design dopaminergic neuron extracellular inhibitor/antagonist insight neurotoxic neurotoxicity novel oxidation pars compacta prevent programs toxicant uptake

项目摘要

DESCRIPTION (provided by applicant): Our long term goal is to study the mechanism of neurodegeneration induced by environmental neurotoxicants. This proposal is submitted to investigate the active role of astrocytes in regulating the levels of environmental neurotoxic cations and hence, in modulating neurodegeneration. Based on our preliminary data we hypothesize that cations such as MPP+ (1-methyl-4-phenylpyridinium) and paraquat (PQ) are bi- directionally transported across the astrocytic plasma membrane by the organic cation transporter 3 (OCT3) and, through this mechanism, OCT3 modulates neurotoxicity. Thus, the tissue and cellular distribution of OCT3 should be critical in defining the differential regional susceptibility to cationic neurotoxins. Cations representing two different categories of environmental neurotoxicants with different toxicokinetics will be used. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a lipophillic compound that will be used to generate MPP+ inside of astrocytes. The goal is to assess how the release of MPP+ from astrocytes (v/a OCT3) into the extracellular space would subsequently induce selective death in the nigral dopaminergic neurons. PQ, a widely used cationic herbicide that has been linked to parkinsonism, will be used to assess how astrocytes affect neurodegeneration by taking up (via OCT3) and thus removing toxic cations from the extracellular space. Of note, both MPP+ and PQ also increase the outflow of the endogenous cation dopamine (DA), which is neurotoxic upon oxidation To test our hypotheses, mutant mice deficient in OCT3 and an OCT3 inhibitor will be used. In the first specific aim, we will assess how OCT3 regulates the levels of MPP+, PQ and DA by determining its uptake and reverse transport kinetics for these cations using both cell culture and animal models. In the second specific aim, we will evaluate how OCT3 modulates neurotoxicity through its bi-directional transport of MPP+ and PQ. We hypothesize that OCT3 ablation, by sequestrating MPP+ in astrocytes, attenuates dopaminergic neuronal death after MPTP treatment. Conversely, OCT3 ablation, by preventing the uptake of MPP+, PQ, and DA into astrocytes, enhances dopaminergic neuronal death after MPP+ and PQ treatments. Thus, our plan is to assess the magnitude of dopaminergic neurotoxicity in OCT3 mutant mice as well as co-culture models of astrocytes and dopaminergic neurons, treated with MPTP, MPP+ or PQ. We will also assess whether re-expression of OCT3 in astrocytes deficient in this transporter would reverse the neurotoxic effects. The proposed studies have potential to unravel a still unrecognized pathway by which different cell types in the brain interact with each other to modulate neurodegeneration induced by environmental toxicants. In addition, these studies may provide significant insights into a novel mechanism that contributes to the pattern of cell death as seen in neurodegenerative disorders such as sporadic Parkinson's disease.

描述（由申请人提供）：我们的长期目标是研究由环境神经毒性引起的神经变性机制。该提案提交以研究星形胶质细胞在调节环境神经毒性阳离子水平，因此在调节神经变性方面的积极作用。根据我们的初步数据，我们假设阳离子（例如MPP+（1-甲基-4-苯基吡啶丁））和Paraquat（PQ）通过有机阳离子阳离子3（OCT3）以及通过这种机械机制通过有机阳离子阳离子3（OCT3）跨星形胶质细胞膜膜进行双向转运。因此，OCT3的组织和细胞分布对于确定阳离子神经毒素的差异敏感性至关重要。将使用代表两种不同类别的具有不同毒性动力学的环境神经毒性的阳离子。 1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）是一种脂肪化合物，可用于在星形胶质细胞内生成MPP+。目的是评估从星形胶质细胞（V/A OCT3）中释放MPP+如何在细胞外空间中释放，随后会诱导ni骨多巴胺能神经元的选择性死亡。 PQ是一种与帕金森氏症相关的广泛使用的阳离子除草剂，将用于评估星形胶质细胞如何通过摄取（通过OCT3）来影响神经变性，从而从细胞外空间中去除有毒阳离子。值得注意的是，MPP+和PQ都增加了内源性阳离子多巴胺（DA）的流出，该多巴胺（DA）在氧化后具有神经毒性以检验我们的假设，将使用OCT3中的突变小鼠，并且将使用OCT3抑制剂。在第一个特定目标中，我们将通过使用细胞培养和动物模型来确定这些阳离子的摄取和反向转运动力学来评估OCT3如何调节MPP+，PQ和DA的水平。在第二个特定目标中，我们将通过其MPP+和PQ的双向转运来评估OCT3如何调节神经毒性。我们假设通过螯合星形胶质细胞中的MPP+，oct3消融会减弱MPTP治疗后多巴胺能神经元死亡。相反，通过防止MPP+，PQ和DA进入星形胶质细胞的摄取，可以增强MPP+和PQ处理后的多巴胺能神经元死亡，从而消融。因此，我们的计划是评估OCT3突变小鼠中多巴胺能神经毒性的大小，以及用MPTP，MPP+或PQ处理的星形胶质细胞和多巴胺能神经元的共培养模型。我们还将评估在该转运蛋白缺乏的星形胶质细胞中对OCT3的重新表达是否会逆转神经毒性作用。拟议的研究有可能揭示仍然无法识别的途径，通过该途径，大脑中的不同细胞类型相互相互作用以调节由环境有毒物质诱导的神经变性。此外，这些研究可能会提供对一种新型机制的重大见解，该机制有助于细胞死亡的模式，如神经退行性疾病（如散发性帕金森氏病）所见。