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）在神经退行性变过程中的作用。 我们 假设（a）DA氧化为自由基， 反应性DA醌导致DA的选择性破坏 末端，（B）这将发生与外源性和内源性 DA，并且选择性是由于存在高水平的 在发生氧化的末端内的细胞质DA。 我们 已经在大鼠中表明，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酰- 儿茶酚，并显示出对DA的选择性毒性的证据 terminals. 在拟议的实验中，我们将研究更多 深入研究DA对大鼠的毒性作用 模型采用生化指标DA氧化和生化 和免疫组化毒性指数。 一是 严格检查外源性DA是否产生选择性的 损失DA终端，以及终端的损失是否导致 黑质中DA细胞的随后损失。 其次我们 将研究DA终端对DA诱导的 在更容易与疾病相关的条件下的毒性 如老年人、抗氧化剂缺乏者或代谢紊乱者， 受损大鼠 此外，我们将研究神经毒性作用 长期给予纹状体内DA和诱导DA 内源性DA的可用性增加后， 暴露于L-dOPA的6-OHDA损伤大鼠。 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 终端DA诱导的氧化应激。这组研究 将研究DA的作用，而不是其他氧化剂，和 阻断DA摄取或DA代谢对选择性 DA末端毒性。 最后，我们将开始检查 DA醌结合的潜在蛋白质靶点， 和细胞外。 细胞外反应的特异性作用 代谢产物对DA受体结合的影响将作为 本研究 这些研究的结果将有助于澄清 DA的反应性代谢产物是否可能有助于 发病机制与DA神经元的损失， 帕金森氏病以及识别潜在有用的 治疗干预。

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.