METABOLISM AND NEUROTOXICITY STUDIES OF MPTP ANALOGS

我们建议研究的代谢命运和神经毒理学 一系列化合物的性质，这些化合物在结构上与 帕金森病诱导神经毒素1-甲基-4- 苯基-1，2，3，6-四氢吡啶（MPTP），并显示神经毒性 对猴的影响（苯氧基四氢吡啶1和吡咯 取代的4-哌啶醇4），在人[4-对氯苯基取代的 4-哌啶醇氟哌啶醇（5）]或小鼠（1-甲基吡咯-2-基 MPTP的模拟物3）。根据MPTP的记录作用机制， 这些研究将集中在代谢的形成和中枢神经系统的访问， 相应的吡啶盐物种，潜在的终极神经毒素。所有 的测试化合物是部分氧化的哌啶衍生物， 预计中间体亚胺离子代谢物将经历 自发氧化成相应的吡啶鎓物质。的 测试化合物的神经毒性特性将通过经典的 小鼠中的神经递质消耗和组织病理学研究。在 除了标准的染色技术，我们将使用免疫细胞化学 染色以识别可能涉及特定 神经递质系统这些研究将不仅限于 多巴胺能系统，因为吡啶衍生物似乎通常 依赖于转运蛋白的特异性神经毒性 本地化预期的吡啶代谢物的毒性将 在直接脑内注射或脑内注射后进行评估 通过微透析进行灌注。研究了这些吡啶盐的抗氧化能力， 化合物抑制线粒体呼吸，这是一个明显的强制性步骤， 在通过其吡啶代谢物介导MPTP的神经毒性中， 将在细胞培养中借助于基于超活性染料的 使用荧光分光检测器的测定， 随着时间的推移，单个细胞或一组细胞中的线粒体功能。这 多学科计划将受益于几个输入 顾问的主要研究活动依赖于拟议的 技术.氟哌啶醇的初步结果， 四氢吡啶衍生物和相应的吡啶鎓衍生物 支持这一建议的主要论点，即部分 氧化的1，4-二取代的哌啶衍生物将被生物转化为 神经毒性吡啶代谢物，可进入中枢神经系统 系统

We propose to investigate the metabolic fate and neurotoxicological properties of a series of compounds that are structurally related to the Parkinsonian inducing neurotoxin 1-methyl-4-- phenyl-1,2,3,6-tetrahydropyridine (MPTP) and which display neurotoxic effects in the monkey (the phenoxytetrahydropyridine 1 and pyrrole substituted 4-piperidinol 4), in man [the 4-pchlorophenyl substituted 4-piperidinol haloperidol (5)] or in the mouse (the 1-methylpyrrol-2-yl analog 3 of MPTP). Based on the documented mechanism of action of MPTP, these studies will focus on the metabolic formation and CNS access of the corresponding pyridinium species, the potential ultimate neurotoxins. All of the test compounds are partially oxidized piperidine derivatives and it is anticipated that the intermediate iminium ion metabolites will undergo spontaneous oxidation to the corresponding pyridinium species. The neurotoxic properties of the test compounds will be evaluated by classical neurotransmitter depletion and histopathology studies in the mouse. In addition to standard staining techniques, we will use immunocytochemical stains to identify specific lesions that may involve a particular neurotransmitter system. These studies will not be limited to the dopaminergic system since pyridinium derivatives appear to be generally neurotoxic with specificity being dependent on transporter based localization. The toxicity of the anticipated pyridinium metabolites will be assessed following direct intracerebral injection or intracerebral perfusion by microdialysis. Studies on the ability of these pyridinium compounds to inhibit mitochondrial respiration, an apparent obligatory step in the mediation of the neurotoxicity of MPTP by its pyridinium metabolite, will be investigated in cell culture with the aid of a supravital dye based assay which employs a spectrofluorometric detector that can estimate mitochondrial function in a single cell or group of cells over time. This multidisciplinary program will benefit from the input of several consultants whose principal research activities rely on the proposed techniques. Preliminary results obtained with haloperidol, its tetrahydropyridine derivative and the corresponding pyridinium derivative support the principal thesis of this proposal, namely that partially oxidized 1,4-disubstituted piperidine derivatives will be biotransformed to neurotoxic pyridinium metabolites that have access to the central nervous system.