The existent pre-clinical models of Parkinson's disease do not simultaneously recapitulate severe degeneration of dopamine neurons and the occurrence of alpha-synuclein (aSyn) aggregation in one study system. In this study, we injected aSyn pre-formed fibrils (PFF) and 6-hydroxydopamine (6-OHDA) unilaterally into the striatum of C57BL/6 wild-type male mice at an interval of 2 weeks to induce aggregation of aSyn protein and trigger the loss of dopamine neurons simultaneously in one model and studied the behavioural effects of the combination in these mice. 6-OHDA was tested at three different doses, and 2 μg of 6-OHDA combined with PFF-induced aSyn aggregation was found to produce the most optimal disease phenotype. At 14 weeks timepoint, mice injected with a combination of PFF and 6-OHDA sustained significant damage to the nigrostriatal pathway and exhibited aSyn-positive aggregation. Our data suggest that the neurons that formed large aSyn aggregates were particularly vulnerable to 6-OHDA-induced degeneration. We also demonstrate the manifestation of a relatively aggressive pathology in 2- to 4-month-old mice, as compared to younger 7- to 9-week-old ones. Furthermore, cerebral dopamine neurotrophic factor (CDNF) administered intrastriatally rescued dopamine neurons and motor behaviour of the animals to some extent from 6-OHDA toxicity. However, no such effect could be seen in the novel 6-OHDA + PFFs combination model. For the first time, we demonstrate the combined effect of PFF and 6-OHDA simultaneously in one model. We further discuss the scope for further optimizing this combination model to develop it as a promising pre-clinical platform for drug screening and development.

中文翻译：

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在帕金森病小鼠模型中结合原纤维诱导的α-突触核蛋白聚集和6-羟基多巴胺以及脑多巴胺神经营养因子对诱导的神经变性的影响

现有的帕金森病临床前模型并不能在一个研究系统中同时重现多巴胺神经元的严重退化和α-突触核蛋白（aSyn）聚集的发生。在本研究中，我们将aSyn预形成原纤维（PFF）和6-羟基多巴胺（6-OHDA）单侧注射到C57BL/6野生型雄性小鼠的纹状体中，间隔2周诱导aSyn蛋白聚集并触发在一个模型中同时损失多巴胺神经元，并研究了该组合对这些小鼠的行为影响。在三种不同剂量下测试了 6-OHDA，发现 2 μg 6-OHDA 与 PFF 诱导的 aSyn 聚集相结合可产生最佳的疾病表型。在第 14 周的时间点，注射 PFF 和 6-OHDA 组合的小鼠的黑质纹状体通路受到显着损伤，并表现出 aSyn 阳性聚集。我们的数据表明，形成大型 aSyn 聚集体的神经元特别容易受到 6-OHDA 诱导的退化的影响。我们还证明了与 7 至 9 周大的小鼠相比，2 至 4 个月大的小鼠表现出相对侵袭性的病理学表现。此外，纹状体内施用脑多巴胺神经营养因子（CDNF）在一定程度上可以挽救动物的多巴胺神经元和运动行为，使其免受6-OHDA毒性的影响。然而，在新颖的 6-OHDA + PFFs 组合模型中看不到这种效果。我们首次在一个模型中同时证明了 PFF 和 6-OHDA 的综合作用。我们进一步讨论了进一步优化该组合模型的范围，以将其开发为有前景的药物筛选和开发临床前平台。