类叶升麻苷抗Aβ神经毒性的作用机制及其与NGF信号通路的关系

One of the APP-derived metabolites, Aβ, is believed to play a key role in AD pathogenesis. Our previous works have found that acteoside has a potent neuroprotective effect against Aβ42-induced neurotoxicity, and the mechanisms Involved increasing the levels of both NGF and its receptor proteins, but we didn’t know the mechanism between them. A lot of evidence suggests these two membrane protein’s functions are strictly interconnected and that the NGF signaling pathway involved in the de-regulation of APP processing that causes AD and be used as a therapeutic target to correct such a deregulation. Accordingly, in this study, we investigated the effcts of acteoside on beta-amyloid-induced PC12 cells and APP/PS1 double transgenic mouse models of AD, and to verification that acteoside could protect nerve injury induced by Aβ, and the mechanism associated with the regulation of NGF signaling. To further, we applied the inhibitors of NGF signaling treated the beta-amyloid-induced PC12 cells to study that Interrelated mechanisms between beta-amyloid induced neurotoxicity and NGF signaling, and to find that actoside treated AD whether effect on Interrelated between beta-amyloid induced neurotoxicity and NGF signaling or with NGF mimic activity. Moreover, acteoside may provide a novel therapeutic strategy for the treatment in AD.

Aβ神经毒性是阿尔茨海默症发病的重要因素，我们前期研究发现类叶升麻苷（AS）具有抗Aβ神经毒性作用且机制涉及NGF及其受体表达的调节作用，但两者之间的作用机制不清楚。大量研究表明，在AD的发生、发展过程中，NGF信号通路和Aβ的生成过程是密切相连的，两者之间的相互作用成为AD药物研究的新靶点。据此，本项目通过Aβ诱导PC12损伤细胞和APP/PS1转基因动物实验，验证AS抗Aβ神经毒性作用，明确NGF信号通路介导AS抗Aβ神经毒性作用；利用抑制剂特异性阻断Aβ诱导PC12损伤细胞的NGF信号通路及其下游通路关键途径，明确AS抗Aβ神经毒性与NGF通路相互作用机制，揭示AS防治AD的作用是由其调节Aβ神经毒性作用与NGF信号通路之间的相互作用产生，亦或是AS具有拟NGF活性引发，进一步明晰AS防治AD的作用机制，为其应用研究提供理论依据，为AD药物研究提供新的研究策略和思路。

通过本次研究，明确了类叶升麻苷（AS，AE）对APP/PS1转基因痴呆小鼠认知功能障碍的影响，明确了NGF信号通路介导AS抗Aβ神经毒性作用，明确了AS抗Aβ神经毒性与NGF通路相互作用机制。实验中，采用Aβ1-42孵育PC12细胞模型以及APP/PS1转基因小鼠（雌雄各半）模型考察了AS对Aβ1-42损伤后PC12细胞的存活率、对Aβ1-42损伤后PC12细胞的凋亡、对模型小鼠新物体识别、筑巢评分、Morris水迷宫及跳台实验的作用，以及对血清、海马及皮层中Aβ1-40、Aβ1-42、Aβ寡聚体、Aβ沉积的影响；通过western-blot检测小鼠皮层和海马区TrkA/p75NTR 信号途径、MAPK信号途径和PI3K/Akt/mTOR信号途径的调节作用，并通过蛋白组学研究AS改善APP/PS1双转基因小鼠认知功能的靶标和途径差异表达基因的鉴定。结果发现，AS能够改善模型细胞的存活率和细胞凋亡现象，改善模型小鼠的空间学习记忆和非空间学习记忆以及Aβ寡聚体的生成，减少脑部Aβ沉淀，调节Aβ代谢过程的相关蛋白和神经营养因子及受体的表达、以及调节NGF介导的TrkA/p75NTR 信号途径和PI3K/Akt/mTOR信号途径相关蛋白的表达，但不影响NGF介导的MAPK信号途径的表达。蛋白组学研究AS改善APP/PS1双转基因小鼠认知功能的靶标和途径差异表达基因的鉴定研究结果显示，AS能够明显调节基因的表达，并对与神经相关的基因尤其是神经突触的影响明显。