DOPAMINE REGULATION IN THE SELECTIVE VULNERABILITY OF DOPAMINERGIC NEURONS

本项目将重点研究活性代谢物的作用。 多巴胺(DA)在神经退变过程中的作用我们 假设(A)DA氧化为自由基和 反应性DA对苯二酚的选择性破坏作用 终端，(B)这将发生在外源和内源的情况下 DA，以及‘选择性是由于存在高水平的 在发生氧化的末端，胞质中有DA。我们 已经在大鼠身上表明纹状体内注射DA会导致 DA氧化产物的形成，蛋白质结合的半胱氨酸基- 儿茶酚，并显示对DA有选择性毒性的证据 终点站。在拟议的实验中，我们将检查更多 大鼠多巴胺中毒现象的研究进展 DA氧化生化指标与生化指标的关系模型 和免疫组织化学毒性指标。首先，我们将 严格检查外源性DA是否会产生选择性 丢失DA终端，以及终端丢失是否会导致 随后黑质中DA细胞的丢失。其次，我们 将检查DA终端对DA诱导的脆弱性 在更容易与疾病相关的条件下的毒性 例如老年人，抗氧化剂缺乏，或新陈代谢- 受损的老鼠。此外，我们还将检查神经毒性效应。 纹状体内长期给药的多巴胺及其诱因 内源DA利用率增加后的氧化作用 6-羟基多巴胺损毁大鼠暴露于L-多巴。第三，我们将 研究DA摄取和DA代谢的作用 与DA的选择性脆弱性相关的机制 DA诱导的氧化应激的终末。这组研究 将研究DA相对于其他氧化剂的作用，以及 阻断多巴胺摄取或代谢对选择性脑损伤的影响 对多巴胺终末的毒性。最后，我们将开始检查 DA苯醌与细胞内结合的潜在蛋白质靶点 以及细胞外。胞外反应的特殊作用 关于DA受体结合的代谢物将作为 这项研究。这些研究的结果将有助于澄清 多巴胺的反应性代谢物是否可能对 大鼠脑内DA能神经元缺失的发病机制 帕金森氏症以及识别潜在有用的 治疗性干预。

This project will focus on the role of reactive metabolites of dopamine (DA) in the process of neurodegeneration. We hypothesize that (a) the oxidation of DA to free radicals and reactive DA quinones results in the selective destruction of DA terminals, (b) this will occur with both exogenous and endogenous DA, and ' the selectivity is due to the presence of high levels of cytoplasmic DA within the terminal where oxidation occurs. We have shown in rats that an intrastriatal injection of DA results in the formation of DA oxidation products, proteins-bound cysteinyl- catechols, and show evidence of selective toxicity to DA terminals. In the proposed experiments, we will examine more thoroughly the phenomenon of DA-induced toxicity in the rat model using biochemical indices of DA oxidation and biochemical and immunohistochemical indices of toxicity. First, we will rigorously examine whether exogenous DA produces a selective loss DA terminals, and whether the loss of terminals results in the subsequent loss of DA cells in the substantia nigra. Secondly, we will examine the vulnerability of DA terminals to DA-induced toxicity under conditions more readily associated with the disease such as in the aged, antioxidant-deficient, or metabolically- impaired rat. In addition, we will examine the neurotoxic effects of chronically administered intrastriatal DA and induces of DA oxidation following increased availability of endogenous DA in the 6-OHDA-lesioned rat exposed to L-dOPA. Thirdly, we will examine the role of DA uptake and DA metabolism as the mechanism associated with the selective vulnerability of DA terminals to DA-induced oxidative stress. This group of studies will examine the role of DA as opposed to other oxidants, and the effect of blocking DA uptake or DA metabolism on the selective toxicity to DA terminals. Finally, we will begin to examine potential protein targets of DA quinone binding both intracellularly and extracellularly. Specific effects of extracellular reactive metabolites on DA receptor binding will be examined as part of this study. The results of these studies will help to clarify whether reactive metabolites of DA may be contributing to the pathogenesis associated with the loss of DA neurons in Parkinson's disease as well as identify potentially useful therapeutic interventions.