Data_Sheet_1_Nicotine-mediated effects in neuronal and mouse models of synucleinopathy.docx

IntroductionAlpha-synuclein (α-Syn) aggregation, transmission, and contribution to neurotoxicity represent central mechanisms underlying Parkinson’s disease. The plant alkaloid “nicotine” was reported to attenuate α-Syn aggregation in different models, but its precise mode of action remains unclear.
MethodsIn this study, we investigated the effect of 2-week chronic nicotine treatment on α-Syn aggregation, neuroinflammation, neurodegeneration, and motor deficits in D-line α-Syn transgenic mice. We also established a novel humanized neuronal model of α-Syn aggregation and toxicity based on treatment of dopaminergic neurons derived from human induced pluripotent stem cells (iPSC) with α-Syn preformed fibrils (PFF) and applied this model to investigate the effects of nicotine and other compounds and their modes of action.
Results and discussionOverall, our results showed that nicotine attenuated α-Syn-provoked neuropathology in both models. Moreover, when investigating the role of nicotinic acetylcholine receptor (nAChR) signaling in nicotine’s neuroprotective effects in iPSC-derived dopaminergic neurons, we observed that while α4-specific antagonists reduced the nicotine-induced calcium response, α4 agonists (e.g., AZD1446 and anatabine) mediated similar neuroprotective responses against α-Syn PFF-provoked neurodegeneration. Our results show that nicotine attenuates α-Syn-provoked neuropathology in vivo and in a humanized neuronal model of synucleinopathy and that activation of α4β2 nicotinic receptors might mediate these neuroprotective effects.

引言
α-突触核蛋白（Alpha-synuclein，α-Syn）的聚集、传播及其介导的神经毒性是帕金森病（Parkinson’s disease）发病的核心机制。已有研究显示，植物生物碱尼古丁可在多种模型中抑制α-Syn聚集，但其确切的作用机制仍未阐明。

方法
本研究探究了为期2周的慢性尼古丁给药对D系α-Syn转基因小鼠体内α-Syn聚集、神经炎症、神经退行性变及运动功能缺陷的影响。此外，我们基于人诱导多能干细胞（human induced pluripotent stem cells，iPSC）来源的多巴胺能神经元经α-Syn预成型纤维（PFF）处理后，构建了一种新型的α-Syn聚集与毒性的人源化神经元模型，并利用该模型探究尼古丁及其他化合物的作用效果与作用机制。

结果与讨论
整体而言，本研究结果表明尼古丁可在两种模型中均抑制α-Syn诱导的神经病理损伤。进一步探究烟碱型乙酰胆碱受体（nicotinic acetylcholine receptor，nAChR）信号通路在iPSC来源多巴胺能神经元中尼古丁神经保护作用的机制时，我们发现：尽管α4亚基特异性拮抗剂可抑制尼古丁诱导的钙信号响应，但α4亚基激动剂（如AZD1446与安纳他品）可介导类似的、针对α-Syn PFF诱导神经退行性变的神经保护效应。本研究结果证实，尼古丁可在体内及突触核蛋白病的人源化神经元模型中抑制α-Syn诱导的神经病理损伤，而α4β2烟碱型受体的激活可能介导了上述神经保护作用。