Dopamine Homeostasis, Vesicles & Neurodegeneration

描述：(摘自申请者的摘要)帕金森氏症是一种 由于黑质多巴胺神经元的丧失而导致的衰弱运动障碍。 帕金森病患者线粒体缺陷与能量损伤和代谢有关 压力是其病因中的潜在因素。此外，DA氧化产物 可能会增加DA神经元内的氧化负担，再加上 持续的代谢应激，可能会导致神经变性。流行病学 研究将帕金森病与环境中农药等物质的暴露联系起来。- 许多杀虫剂都是线粒体抑制剂。一种潜在的保护形式 抗线粒体毒素(即MPP+)可能是将它们固存到 DA神经元的突触小泡。这个项目的目标是获得一个 理解囊泡的作用，囊泡的单胺转运体 (VMAT2)和DA在调控线粒体引起的神经退行性变中的作用 毒素。一种假设是线粒体毒素的作用可以是 根据毒素是否被隔离而以不同的方式进行调节 变成囊泡。如果被隔离，毒素暴露可能会被取消。相比之下， 囊泡功能毒素的破坏可能导致DA动态平衡紊乱 以及增强的毒性，因为它会从与 线粒体。在目标1中，将检测几种线粒体毒素 干扰囊泡功能的能力(即抑制DA摄取到 分离的大鼠膜囊泡)。在目标2中，大鼠中脑培养物或大鼠 纹状体将暴露在VMAT2抑制后的线粒体毒素中 确定毒性是否被修改。来检验扰乱DA的假说 动态平衡导致新陈代谢应激产生的退化，两个 将使用各种方法。首先，DA将在暴露之前耗尽 培养或大鼠纹状体转化为线粒体抑制物。第二，囊泡内容物 (DA)暴露于线粒体后将被释放到胞浆中 毒素检查代谢过程中DA动态平衡是否被放大破坏 压力会增加毒性。此外，假设物质是 不是线粒体抑制剂本身，而是可以扰乱小泡中DA的存储 在新陈代谢应激期间可能放大损伤将在AIM中进行检查 3.在目标4中，假设氧化应激等早期事件会导致 小泡功能丧失，DA动态平衡紊乱，并加重 将对毒素引起的神经退行性变进行调查。离体囊泡 将测试其对氧化和还原条件的敏感性。 这些研究的结果将提供关于以下方面的新的相关信息 VMAT2囊泡在神经保护中的作用 代谢性应激过程中DA神经元的神经变性。

DESCRIPTION: (Verbatim from the Applicant's Abstract) Parkinson's disease is a debilitating motor impairment disorder due to loss of nigral dopamine neurons. Mitochondrial defects in PD patients implicate energy impairment and metabolic stress as potential factors in its etiology. Moreover, DA oxidation products may add to the oxidative burden within DA neurons which, coupled with a persistent metabolic stress, may lead to neurodegeneration. Epidemiological studies link PD with environmental exposure to substances such as pesticides. - Many pesticides are mitochondrial inhibitors. A potential form of protection against mitochondrial toxins (i.e., MPP+) may be their sequestration into synaptic vesicles of DA neurons. The goal of this project is to gain an understanding of the role of vesicles, the vesicular monoamine transporter (VMAT2) and DA in modulating neurodegeneration produced by mitochondrial toxins. One hypothesis is that the actions of mitochondrial toxins can be modulated in contrasting ways depending on whether the toxins are sequestered into vesicles. If sequestered, toxin exposure could be abrogated. In contrast, disruption of vesicular function toxin could lead to disturbed DA homeostasis and enhanced toxicity since it would remove the toxin from interaction with mitochondria. In Aim 1 several mitochondrial toxins will be examined for their ability to interfere with vesicle function (i.e. to inhibit DA uptake into isolated rat membrane vesicles). In aim 2, rat mesencephalic cultures or rat striata will be exposed to mitochondrial toxins following VMAT2 inhibition to determine if toxicity is modified. To examine the hypothesis that disturbed DA homeostasis contributes to degeneration produced by metabolic stress, two approaches will be used. First, DA will be depleted prior to exposure of culture or rat striata to a mitochondrial inhibitor. Second, vesicle contents (DA) will be released into the cytosol after exposure to the mitochondrial toxin to examine if augmented disruption of DA homeostasis during the metabolic stress enhances toxicity. Additionally, the hypothesis that substances that are not themselves mitochondrial inhibitors, but can disrupt DA storage in vesicles may amplify damage during episodes of metabolic stress will be examined in Aim 3. In aim 4 the hypothesis that early events such as oxidative stress leads to loss of vesicle function, disruption of DA homeostasis and exacerbation of neurodegeneration produced by toxins will be investigated. Isolated vesicles will be tested for their sensitivity to oxidizing and reducing conditions. Results from these studies will provide novel and relevant information as to the contribution of VMAT2 containing vesicles in neuroprotection as well as in neurodegeneration of DA neurons during metabolic stress.