Extra-nigral Neurodegeneration in Experimental Parkinson's Disease

帕金森病(PD)是一种进行性退行性运动障碍，与多巴胺丢失有关- 黑质(SN)中的GIC神经元导致功能障碍。目前的治疗方法L-多巴并不能阻断糖尿病的发生。 因此，必须开发新的治疗方法。因此，目的是调查炎症性疾病 脑和脊髓(SC)的事件及其在帕金森病中的退变，并表征SC的完整性和 帕金森病中神经元丢失，导致功能障碍。了解损伤的机制可能有助于消除 开发新的治疗策略。虽然帕金森病的病因还不完全清楚，但神经毒素已经被注入。 参与帕金森病的发病机制。有毒的1-甲基-4-苯基-1，2，3，6-四氢吡啶(MPTP)已被广泛应用 用作实验模型。由于1-甲基-4-苯基吡啶离子(MPP)的活性毒性代谢物 MPTP，升高细胞内游离钙水平，促进线粒体功能障碍，是一种钙介导的病理机制。 帕金森病的病史已经被假设了。升高的钙水平会促进钙蛋白酶的激活，增加炎症- 托利反应，并损害脑/SC神经元、轴突和髓鞘，最终导致功能缺陷。我们的 直接检测PD小鼠SC中MPP、星形胶质细胞和小胶质细胞活化的初步结果 神经元中钙蛋白酶活性和表达的增加表明SC也受到影响。这些发现是 初步数据证实，帕金森病患者SC的运动神经元也受到了损害。MPP 腹侧SC运动神经元细胞(VSC4.1)处理后细胞内[Ca~(2+)]和钙蛋白酶活性升高 在钙蛋白酶抑制剂(CalPeptin，SJA6017)保护和恢复时，膜电位丧失和死亡 细胞功能。根据这些发现，我们假设，由于SC协调运动和感觉 对身体来说，除了黑质外，SC神经元、轴突和髓鞘的损伤可能是一个重要因素 在帕金森氏病中，钙蛋白酶通过促进炎症和细胞死亡在这种功能障碍中发挥关键作用 并可能成为治疗的目标。三个具体目标将检验这些假说。特定目标1将调查 MPTP在SC中是否直接转化为MPP，是通过来自大脑的退行性轴突进入，还是通过 观察MPTP(MPP)对急性脑缺血大鼠黑质和SC神经元及脑白质的影响。 和慢性帕金森综合征；评估Calain的表达和活性以及随后的炎症和细胞 并检测帕金森病死后患者SC内神经元、轴突和髓鞘的状态。特定的 目的2探讨MPP对分化的VSC4.1细胞的神经毒性作用及其神经保护作用 电生理技术研究钙蛋白酶抑制剂的体外药效。《特定目标3》将审查 钙蛋白酶抑制剂治疗是否会减轻炎症，防止脑和SC神经元的凋亡， 保护细胞，保护轴突和髓鞘，改善MPTP诱导的PD小鼠的功能。这些研究将 阐明钙蛋白酶在MPTP诱导的帕金森病炎症和神经变性中的作用以及可能的 钙蛋白酶抑制剂治疗帕金森病的神经保护作用。

Parkinson's disease (PD), a progressive degenerative movement disorder associated with loss of dopaminer- gic neurons in substantia nigra (SN), leads to dysfunction. The current therapy, L-dopa, does not block dis- ease progression; therefore, new therapies must be developed. Thus, the aim is to investigate inflammatory events in brain and spinal cord (SC) and their degeneration in PD and characterize whether SC integrity and neurons are lost in PD, contributing to dysfunction. Understanding the mechanisms of damage may help de- velop new therapeutic strategies. While the etiology of PD is not fully understood, neurotoxins have been im- plicated in PD pathogenesis. Toxic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been extensively used as an experimental model. Since 1-methyl-4-phenylpyridinium ion (MPP+), the active toxic metabolite of MPTP, increases intracellular-free Ca2+ level and promotes mitochondrial dysfunction, a Ca2+-mediated pathol- ogy in PD has been hypothesized. Increased Ca2+ levels will promote calpain activation, increase inflamma- tory responses, and damage brain/SC neurons, axons, and myelin, ultimately leading to functional deficit. Our preliminary findings of direct detection of MPP+ in PD mouse SC, activation of astrocytes and microglia, and increased calpain activity and expression in neurons indicate that SC is also affected. These findings were corroborated by preliminary data showing motoneurons from SC of PD patients are also damaged. MPP+ treatment of ventral SC motor neuron cells (VSC4.1) showed increased intracellular [Ca2+] and calpain activity with loss of membrane potential and death while calpain inhibitors (calpeptin, SJA6017) protected and restored cell function. From these findings, we hypothesize that, since SC coordinates movement and sensation of the body, damage to SC neurons, axons, and myelin, in addition to SN, may be an important factor in PD, and calpain plays a crucial role in this dysfunction by promoting inflammation and cell death and may be a target for therapy. Three specific aims will test the hypotheses. Specific Aim 1 will investigate whether MPTP is directly converted into MPP+ in SC, enters through the degenerating axons from brain, or a combination of both; examine the effects of MPTP (MPP+) on SN and SC neurons and white matter in acute and chronic parkinsonism; assess calpain expression and activity and subsequent inflammation and cell damage; and examine the status of neurons, axons, and myelin in SC of postmortem PD patients. Specific Aim 2 will explore the effects of neurotoxic MPP+ in differentiated VSC4.1 cells and test the neuroprotective efficacy of calpain inhibitors in vitro employing electrophysiological technique. Specific Aim 3 will examine whether calpain inhibitor treatment will attenuate inflammation, prevent apoptosis of brain and SC neurons, protect cells, preserve axons and myelin, and improve function in MPTP-induced PD mice. These studies will delineate the role of calpain in inflammation and neurodegeneration in MPTP-induced PD and the probable neuroprotective efficacy of calpain inhibitors in PD as therapeutic agents.