中国科学院昆明动物研究所机构知识库

帕金森病（Parkinson’s disease, PD）是全球第二大神经退行性疾病。虽然到目前为止并没有有效的手段可以根治PD，但是我们可以从两个方面来尝试延缓PD的发病进程，延长PD病人的寿命。一方面是寻找早期的诊断指标，旨在在PD出现临床明显的运动症状之前对其进行诊断与检测，从而进行早期的干预、治疗及多巴胺神经元的保护；另一方面是继续致力于PD的病因与机制的研究，从根本上对于PD进行防治和治疗。从寻找PD的早期诊断指标这方面来讲，扫视异常，作为PD一个常见、相对早期出现的症状，而且其参数比较容易精确测定，有作为PD早期诊断标志的潜力。PD病人在快速扫视任务中存在扫视幅值不足（Hypometria）的问题，表现为幅度下降，临床上存在多步样（Multiple step pattern, MSP）扫视行为。然而，扫视幅值不足在PD的病程发展中出现的有多早并不清楚，而这恰恰是衡量一个早期诊断指标的关键因素。在本实验中，我们利用侧脑室注射1-甲基-4-苯基-1,2,3,6-四氢吡啶（1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine，MPTP）的方法在猴子上建立PD模型，并在建模过程中观察并分析反应时（Latency）、峰值速度（Peak velocity）以及存在多步样扫视行为的比例（%MSP）等眼动参数的变化，以此来评估扫视幅值不足的问题出现在PD病程的哪个阶段。研究结果发现%MSP的增加出现在临床运动症状之前，而且随着建模过程的发展而持续增加。此外，垂直方向扫视中的MSP出现要早于水平方向，这表明在建模的过程中，垂直方向扫视不足的问题出现要早于水平方向。而扫视异常的出现要早于运动症状这点不仅表明在PD的病程发展中扫视系统比运动系统更早也更容易受到影响，而且提示我们扫视的异常，尤其是垂直方向的扫视幅值不足可以做PD早期诊断的一个指标。从探索PD的病因和致病机制的角度来讲，我们首先应该对于PD的病理变化有一个全面而深入的了解。磷酸化的α-突触核蛋白（Phosphorylation of α-syn at serine 129，P-Ser 129 α-syn）被认为参与到了PD发病机理和路易小体（Lewy body, LB）的形成过程。然而，没有资料对于PD病程发展中P-Ser 129 α-syn聚集与多巴胺神经元丢失之间的关系、路易小体的病理变化以及P-Ser 129 α-syn聚集的分布模式进行过清晰的阐述。本实验中，我们利用建模-恢复-再建模的策略，用MPTP在老龄猴子上建立PD模型，并检测建模猴子脑内黑质（Substantial nigra, SN）以及与PD相关的脑区内的病理变化情况。结果表明，与正常年龄匹配的对照组相比，MPTP建模的猴子黑质内的出现了显著的酪氨酸羟化酶（Tyrosine hydroxylase, TH）阳性神经元的减少和P-Ser 129 α-syn阳性聚集的增加。利用免疫荧光对于TH和P-Ser 129 α-syn进行共染的结果发现P-Ser129 α-syn的聚集和黑质内的一些TH阳性神经元是共定位的，这提示我们P-Ser 129 α-syn的聚集和多巴胺神经元的丢失存在着负相关的关系，而且它们在黑质内的相互作用可能参与到了模型猴子PD症状的发展过程中。此外，我们在新皮层（neocortex）和除SN以外的中脑的其他区域也发现了P-Ser 129 α-syn阳性染色。尤其是在动眼神经核（Oculomotor nucleus, CN III）、颞叶皮层（Temportal cortex, TC）、前额叶皮层（Prefrontal cortex, PFC）以及第三脑室（the third ventricle）周围的细胞内发现了P-Ser 129 α-syn阳性染色。值得指出的是，枕叶皮层（occipital cortex, OC）P-Ser 129 α-syn的染色是阴性的。本实验中发现的路易小体样病理变化、多巴胺神经元丢失与P-Ser 129 α-syn 聚集之间的关系以及稳定的PD症状不仅提示我们这种建模-恢复-再建模的策略在老年猴子上建立的模型也许可以为PD病因的生物学调查以及治疗手段的发展提供一个新的平台，而且也从PD相关病理变化分布形式上为PD的发病机理的研究提供了线索。

Parkinson’s disease (PD) is the second most common neurodegenerative disorder of the world. Though until now, there has been no radical treatment of PD, we can try finding a solution to delay the procession of PD, and prolong the survival time of PD patients from two aspects below. On the one hand, we can find an early biomarker to diagnosis PD before clinical motor symptoms appear, therefore intervening the process, treating PD symptoms, and protecting dopaminergic neurons from a relative earlier period; on the other hand, we can keep focusing on exploring the pathogenesis of PD, therefore fundamentally preventing and curing PD.From the aspect of finding an early biomarker of PD diagnosis, saccadic abnormality, as a common and relatively early onset symptom of PD that can be easily and precisely measured, has the potential to serve as a biomarker in early PD diagnosis. PD patients demonstrate a hypometria problem in saccadic tasks that correlate to reduced saccadic amplitude, with multiple step pattern (MSP) as its main clinical manifestations. However, it is not clear how early the hypometria problem appears in the PD development process, which is a key factor in evaluating earlier diagnostic tools. In this study, PD was modeled with intracerebroventricular 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration in monkeys and changes in saccadic data were analyzed for saccade latency, peak velocity (PV) and the percentage of saccades that display an MSP (%MSP) in order to evaluate which stage hypometria develops in the PD modeling process. It was found that an increased %MSP appeared before the onset of classic diagnostic motor symptoms, and this increase continued throughout the modeling process. Moreover, saccades with MSP appeared earlier in a vertical orientation than in the horizontal orientation, indicating that vertical saccadic hypometria appeared earlier than horizontal saccadic hypometria during modeling process. The early development of saccade abnormalities suggested that the saccadic system was more susceptible than the somatic motor system and that the saccade abnormalities, especially vertical saccadic hypometria might serve as an early biomarker in PD diagnosis. From the aspect of exploring the pathogenesis of PD, we should first get a comprehensive understanding of the pathology that involved in PD. Phosphorylation of α-syn at serine 129 (P-Ser 129 α-syn) is involved in the pathogenesis of PD and Lewy body (LB) formation. However, there is no data to date that clearly illustrates the relationship between P-Ser 129 α-syn accumulation and dopaminergic cell loss, LB pathology and the distribution pattern of P-Ser 129 α-syn in PD development. Here, pathological changes in the substantia nigra (SN) and PD related brain areas were measured in aged monkeys treated with 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) utilizing a modeling-recovery-remodeling strategy. Compared to age-matched controls, the MPTP treated monkeys showed significantly reduced tyrosine hydroxylase (TH) positive neurons and increased P-Ser 129 α-syn positive aggregations in the SN. Double labelling Immunofluorescence found some TH positive neurons to be co-localized with P-Ser129 α-syn in the SN, suggesting the inverse correlation between P-Ser 129 α-syn aggregations and dopaminergic cell loss in the SN may represent an interactive association related to the progression of the PD symptoms in the model. P-Ser 129 α-syn positive staining was also found in the the neocortex and midbrain area besides SN, specifically in the oculomotor nucleus (CN III), temporal cortex (TC), prefrontal cortex (PFC) and in cells surrounding the third ventricle. Notably, the occipital cortex (OC) was P-Ser 129 α-syn negative. The findings of LB-like pathologies, the relationship between dopaminergic cell loss and P-Ser 129 α-syn aggregation, and the stability of the PD symptoms in this model suggest that the modeling-recovery-remodeling strategy in aged monkeys may provide a new platform for biomedical investigations into the etiology of PD and therapeutic development and provide a hint of the pathogenesis of PD from the aspect of PD related pathology distribution pattern.