Environmental Toxicants and Neurodegeneration

环境毒物和神经退行性疾病

基本信息

批准号：
7418175
负责人：
KIM TIEU
金额：
$ 0.89万
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/7418175
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环境神经毒物引起的神经变性的机制。提交该提案是为了研究星形胶质细胞在调节环境神经毒性阳离子水平从而调节神经退行性中的积极作用。根据我们的初步数据，我们假设 MPP+（1-甲基-4-苯基吡啶鎓）和百草枯 (PQ) 等阳离子通过有机阳离子转运蛋白 3 (OCT3) 双向转运穿过星形胶质细胞质膜，并通过这种机制, OCT3 调节神经毒性。因此，OCT3 的组织和细胞分布对于确定不同区域对阳离子神经毒素的敏感性至关重要。将使用代表具有不同毒代动力学的两种不同类别的环境神经毒物的阳离子。 1-甲基-4-苯基-1,2,3,6-四氢吡啶 (MPTP) 是一种亲脂性化合物，将用于在星形胶质细胞内部生成 MPP+。目标是评估 MPP+ 从星形胶质细胞 (v/a OCT3) 释放到细胞外空间随后如何诱导黑质多巴胺能神经元选择性死亡。 PQ 是一种广泛使用的阳离子除草剂，与帕金森症有关，将用于评估星形胶质细胞如何通过吸收（通过 OCT3）并从而从细胞外空间去除有毒阳离子来影响神经变性。值得注意的是，MPP+ 和 PQ 还会增加内源性阳离子多巴胺 (DA) 的流出，而内源性阳离子多巴胺 (DA) 氧化后具有神经毒性。为了测试我们的假设，将使用缺乏 OCT3 和 OCT3 抑制剂的突变小鼠。在第一个具体目标中，我们将使用细胞培养和动物模型确定 OCT3 对这些阳离子的摄取和反向转运动力学，从而评估 OCT3 如何调节 MPP+、PQ 和 DA 的水平。在第二个具体目标中，我们将评估 OCT3 如何通过 MPP+ 和 PQ 的双向转运来调节神经毒性。我们假设 OCT3 消融通过隔离星形胶质细胞中的 MPP+ 来减轻 MPTP 治疗后的多巴胺能神经元死亡。相反，OCT3 消融通过阻止星形胶质细胞摄取 MPP+、PQ 和 DA，增强了 MPP+ 和 PQ 治疗后的多巴胺能神经元死亡。因此，我们的计划是评估 OCT3 突变小鼠以及用 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中多巴胺能神经毒性的程度。我们还将评估在缺乏这种转运蛋白的星形胶质细胞中重新表达 OCT3 是否会逆转神经毒性作用。拟议的研究有可能揭示一条尚未被认识的途径，大脑中不同类型的细胞通过该途径相互作用来调节环境毒物引起的神经退行性变。此外，这些研究可能为导致细胞死亡模式的新机制提供重要见解，如散发性帕金森病等神经退行性疾病中所见。