The Rat Pre-Formed Alpha-Synuclein Fibril Model of Parkinson's Disease

直到最近，还没有一种帕金森氏病(PD)的动物模型充分结合了这两种广泛存在的疾病 α-突触核蛋白(α-SYN)病理和旷日持久的显著黑质纹状体变性。2012年陆炳泉和 同事们描述了纹状体内注射合成的α-SYN如何在野生型(WT)中形成纤维(PFF)。 接种的小鼠细胞内路易体(LB样)样α-SYN包涵体的内源性积累和最终 黑质纹状体变性。鉴于大鼠模型系统比小鼠具有明显的优势 (精细的运动行为，更大的突触复杂性，遗传学和药代动力学更类似于人类， 更大的大脑和身体尺寸更容易接受神经外科手术和样本收集)，我们最近 表征小鼠α-syn pff单侧纹状体内注射的结果。类似于 小鼠，我们观察到磷酸化的α-SYN在神经细胞内的几个区域聚集，这些区域支配着 纹状体，最突出的是额叶和岛叶皮质、杏仁核和黑质。 康培达(SNPC)。α-syn堆积与泛素、p62共定位，且硫代黄素-S阳性。 耐蛋白水解酶K。尽管SNPC内的α-SYN包涵体仍然是纹状体注射的同侧，我们 观察到注射α-syn PFF 6个月后双侧黑质多巴胺神经元的减少。此外，PFF 注射后的大鼠纹状体多巴胺能神经支配减少，纹状体多巴胺缺乏 和代谢物。这项初步研究表明，α-syn pff足以在病理上播种。 内源性α-SYN的转化和增殖诱导α-SYN进行性神经退行性变模型 大鼠的突触核病。在本IGNITE应用中，我们试图识别哪些α-SYN物种(人类， 小鼠、大鼠)导致60%的黑质多巴胺神经元在4个月后的过程中持续丢失 纹状体内注射(目标1)。一旦确定，我们将进行内部验证研究，以 系统地表征α-SYN病理、纹状体多巴胺和 代谢物丢失，纹状体多巴胺能神经支配水平(酪氨酸羟基酶，囊泡单胺 运动行为缺陷(目标2)。最后，我们将进行与PD相关的 外部验证研究包括：1)调查PFF导致的运动障碍是否 用左旋多巴可逆，2)进行黑质纹状体DA合成的无创性纵向体内成像， 使用正电子发射断层扫描(PET)进行储存和周转(目标3)。我们提出了优化， 进展性大鼠α-SYN PFF PD模型的内部验证和外部验证研究将允许 直接与PD患者的临床指标进行比较，促进新的疾病改良剂的开发 治疗。

Until recently no animal model of Parkinson’s disease (PD) has adequately incorporated both widespread alpha-synuclein (α-syn) pathology and protracted significant nigrostriatal degeneration. In 2012 Luk and colleagues described how intrastriatal injection of synthetic α-syn preformed fibrils (PFFs) into wildtype (WT) mice seeded endogenous accumulation of Lewy Body (LB)-like intracellular α-syn inclusions and ultimate nigrostriatal degeneration. In light of the fact that the rat model system offers distinct advantages over mice (fine motor behaviors, greater synaptic complexity, genetics and pharmacokinetics more similar to humans, larger brain and body size more amenable to neurosurgical interventions and sample collection), we recently characterized the results of unilateral injection of mouse α-syn PFFs into the striatum of rats. Similar to the mouse, we observed phosphorylated α-syn intraneuronal accumulations in several areas that innervate the striatum, most prominently the frontal and insular cortices, the amygdala, and the substantia nigra pars compacta (SNpc). α-Syn accumulations co-localized with ubiquitin, p62, and were thioflavin-S-positive and proteinase-k resistant. Although α-syn inclusions within the SNpc remained ipsilateral to striatal injection, we observed bilateral reductions in nigral dopamine neurons 6 months following α-syn PFF injection. Further, PFF injected rats exhibited reductions in striatal dopaminergic innervation as well as deficits in striatal dopamine and metabolites. This initial study demonstrates that α-syn PFFs are sufficient to seed the pathological conversion and propagation of endogenous α-syn to induce a progressive, neurodegenerative model of α- synucleinopathy in rats. In the present IGNITE application we seek to identify which α-syn species (human, mouse, rat) results in consistent loss of 60% nigral dopamine neurons over the course of 4 months after intrastriatal injection into rats (Aim 1). Once identified, we will conduct internal validation studies to systematically characterize the time course and magnitude of α-syn pathology, striatal dopamine and metabolite loss, levels of striatal dopaminergic innervation (tyrosine hydroxylase, vesicular monoamine transporter, and dopamine transporter) and deficits in motor behaviors (Aim 2). Lastly, we will conduct PD-relevant external validation studies including: 1) investigating whether PFF-induced motor deficits are reversible with levodopa and 2) conduct non-invasive longitudinal in vivo imaging of nigrostriatal DA synthesis, storage and turnover using positron emission tomography (PET) (Aim 3). We propose that optimization, internal validation and external validation studies in the progressive rat α-syn PFF PD model will allow for direct comparison to clinical metrics in PD patients and facilitate the development of novel disease modifying therapies.