Calpain inhibitors in models of Parkinson's disease

描述（由申请人提供）：帕金森病是一种神经退行性疾病，特异性影响黑质中的多巴胺能神经元。虽然已经提出了几种假设来解释这种疾病的神经退行性特征的特异性，但这种疾病的确切原因仍有待阐明。我们对帕金森病可能病因的理解取得了重大进展，这是因为我们偶然发现了一种神经毒素，即1-甲基-4-苯基-1，2，3，6-四氢吡啶（MPTP），它能在人类和实验动物中诱发一种与帕金森病患者相同的神经退行性特征。预防帕金森病神经变性的潜在靶点是钙依赖性蛋白酶钙蛋白酶。钙蛋白酶水平在帕金森病患者死后黑质中升高，颗粒细胞培养物中的MPP+神经毒性与钙蛋白酶激活相关并被钙蛋白酶抑制剂阻断，并且钙蛋白酶与几种神经退行性疾病有关。我们最近获得了一系列新的和有效的钙蛋白酶抑制剂，并已证明其在防止NMDA诱导的钙蛋白酶激活培养海马脑片的效力。目前的建议是旨在测试的假设，钙蛋白酶激活在PD的动物模型中起着至关重要的作用，钙蛋白酶抑制剂在这些模型中的神经保护。我们将首先确定钙蛋白酶抑制剂在大鼠中脑培养切片中预防MPTP毒性的效力和功效。然后，我们将使用结构活性关系结合其他测定，以确定在体内模型中测试的最佳抑制剂。最后，我们将测试的假设，钙蛋白酶被激活，钙蛋白酶抑制剂对MPTP介导的神经毒性和行为障碍在体内C57 BI/6小鼠，对鱼藤酮介导的神经毒性大鼠的神经保护。促凋亡因子Bid向其活性截短形式tBid的转化将作为钙蛋白酶激活诱导细胞死亡的机制的一部分进行测试。这些研究将检验钙蛋白酶抑制剂不仅可以预防帕金森病的神经变性，而且可以预防暴露于环境毒素导致的各种疾病的假设。最后，由于钙蛋白酶也与肌萎缩侧索硬化症（ALS）的潜在机制有关，我们的建议也可能导致这种神经退行性疾病的治疗取得重大进展。

DESCRIPTION (provided by applicant): Parkinson' s disease is a neurodegenerative disease that specifically affects dopaminergic neurons in the substantia nigra. Although several hypotheses have been proposed to account for the specificity of the neurodegenerative features of the disease, the exact cause of the disease remains to be elucidated. Significant advances in our understanding of the possible causes of the disease were provided by the serendipitous discovery that a neurotoxin, 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP), elicits a pattern of neurodegenerative features in humans and experimental animals identical to that seen in patients with Parkinson' s disease. A potential target to prevent neurodegeneration in Parkinson' s disease is the calcium-dependent protease calpain. Calpain levels are elevated in post-mortem substantia nigra of patients with Parkinson' s disease, MPP+ neurotoxicity in granule cell cultures is associated with calpain activation and blocked by calpain inhibitors, and calpain has been implicated in several neurodegenerative diseases. We have recently obtained a series of novel and potent calpain inhibitors and have demonstrated their potency in preventing NMDA-induced calpain activation in cultured hippocampal slices. The current proposal is aimed at testing the hypothesis that calpain activation plays a critical role in animal models of PD and that calpain inhibitors are neuroprotective in these models. We will first determine the potency and efficacy of calpain inhibitors to prevent MPTP toxicity in cultured slices from rat mesencephalon. We will then use structure activity relationship in conjunction with additional assays to identify the best inhibitors to be tested in in vivo models. Finally, we will test the hypothesis that calpain is activated and that calpain inhibitors are neuroprotective against MPTP-mediated neurotoxicity and behavioral impairments in vivo in C57BI/6 mice, and against rotenone-mediated neurotoxicity in rats. Conversion of the pro-apoptotic factor Bid to its active, truncated form tBid will be tested as part of the mechanisms by which calpain activation induces cell death. These studies will test the hypothesis that calpain inhibitors might prevent neurodegeneration not only in Parkinson' s disease but also in a variety of conditions resulting from exposure to environmental toxins. Finally, because calpain has also been implicated in the mechanisms underlying Amyotrophic Lateral Sclerosis (ALS), our proposal could lead to significant advances in the treatment of this neurodegenerative disease as well.