Environmental Toxicants and Neurodegeneration

环境毒物和神经退行性疾病

• 批准号: 7629108
• 负责人: KIM TIEU
• 金额: $ 31.73万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 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/7629108
• 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 Culture Techniques; Cell Death; Cell membrane; Cells; Cessation of life; Chemicals; Coculture Techniques; Corpus striatum structure; 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; 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; overexpression; oxidation; pars compacta; prevent; programs; toxicant; uptake

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素诱导的神经退行性变的机制。这个建议是提交调查的积极作用，星形胶质细胞在调节环境神经毒性阳离子的水平，因此，在调制神经退行性变。基于我们的初步数据，我们假设阳离子如MPP+（1-甲基-4-苯基吡啶）和百草枯（PQ）通过有机阳离子转运蛋白3（OCT 3）双向转运穿过星形胶质细胞质膜，并且通过该机制，OCT 3调节神经毒性。因此，OCT 3的组织和细胞分布在确定不同区域对阳离子神经毒素的敏感性方面至关重要。将使用代表两种不同类别的环境神经毒物的阳离子，具有不同的毒性。1-甲基-4-苯基-1，2，3，6-四氢吡啶（MPTP）是一种亲脂化合物，可用于在星形胶质细胞内产生MPP+。目的是评估MPP+从星形胶质细胞（v/a OCT 3）释放到细胞外空间如何随后诱导黑质多巴胺能神经元的选择性死亡。PQ是一种广泛使用的与帕金森病有关的阳离子除草剂，将用于评估星形胶质细胞如何通过摄取（通过OCT 3）从而从细胞外空间中去除有毒阳离子来影响神经变性。值得注意的是，MPP+和PQ还增加了内源性阳离子多巴胺（DA）的流出，多巴胺在氧化后具有神经毒性。为了测试我们的假设，将使用OCT 3和OCT 3抑制剂缺陷的突变小鼠。在第一个具体目标中，我们将评估OCT 3如何通过使用细胞培养和动物模型确定其对这些阳离子的摄取和反向转运动力学来调节MPP+、PQ和DA的水平。在第二个具体目标中，我们将评估OCT 3如何通过MPP+和PQ的双向转运调节神经毒性。我们假设OCT 3消融通过隔离星形胶质细胞中的MPP+，减弱MPTP治疗后多巴胺能神经元的死亡。相反，OCT 3消融通过阻止MPP+、PQ和DA摄取到星形胶质细胞中，增强MPP+和PQ处理后的多巴胺能神经元死亡。因此，我们的计划是评估用MPTP、MPP+或PQ处理的OCT 3突变小鼠以及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OCT 3在缺乏这种转运蛋白的星形胶质细胞中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一种尚未被认识的途径，通过这种途径，大脑中不同类型的细胞相互作用，以调节环境毒物诱导的神经退行性变。此外，这些研究可能会提供一个新的机制，有助于细胞死亡的模式，如在神经退行性疾病，如散发性帕金森氏病的重要见解。