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

直到最近，还没有帕金森病（PD）的动物模型充分地结合了广泛的 α-突触核蛋白（α-syn）病理学和持久的显著黑质纹状体变性。在2012年， 他的同事描述了纹状体内注射合成的α-syn预形成的纤维（PFF）如何进入野生型（WT） 小鼠接种路易体（LB）样细胞内α-syn包涵体的内源性积累， 黑质纹状体变性鉴于大鼠模型系统相对于小鼠具有明显的优势， (fine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适合神经外科干预和样本收集），我们最近 表征了将小鼠α-syn PFF单侧注射到大鼠纹状体中的结果。类似于 小鼠，我们观察到磷酸化的α-syn神经元内的积累在几个领域，支配 纹状体，最显著的是额叶和岛叶皮质，杏仁核和黑质部 （SNPC）.α-Syn积聚与泛素、p62共定位，并且是硫磺素-S阳性， 蛋白酶-K抗性。尽管SNpc中的α-syn包涵体仍然与纹状体注射同侧，我们 在α-syn PFF注射后6个月观察到黑质多巴胺神经元的双侧减少。此外，PFF 注射的大鼠表现出纹状体多巴胺能神经支配减少以及纹状体多巴胺 和代谢物。这项初步研究表明，α-syn PFF足以接种病理性 内源性α-syn的转化和增殖，以诱导α-syn的进行性神经退行性模型。 大鼠的突触核蛋白病。在本IGNITE申请中，我们试图识别哪些α-syn物种（人类， 小鼠，大鼠）在4个月的过程中导致60%的黑质多巴胺神经元的一致损失， 大鼠纹状体内注射（目的1）。一旦确定，我们将进行内部验证研究， 系统地表征α-syn病理学、纹状体多巴胺和 代谢物损失，纹状体多巴胺能神经支配（酪氨酸羟化酶，囊泡单胺 转运蛋白和多巴胺转运蛋白）和运动行为缺陷（目标2）。最后，我们将进行PD相关 外部验证研究包括：1）调查PFF诱导的运动缺陷是否 左旋多巴可逆和2）进行黑质纹状体DA合成的非侵入性纵向体内成像， 储存和周转使用正电子发射断层扫描（PET）（目标3）。我们建议优化， 进行性大鼠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，并促进新疾病修饰的开发 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.