瑞香素抑制CaMKK-CaMKIV通路调节突触囊泡再分配改善AD小鼠认知障碍作用机制研究

Cognitive dysfunction is the main clinical manifestation of Alzheimer's disease (AD), and Aβ is a very important initiating factor which triggers synaptic dysfunction leading to cognitive impairment. Reducing the synaptic damage caused by Aβ and repairing the synaptic function have become the research hotspots in the treatment of AD. Our previous studies have found that daphnetin can inhibit CaMKIV phosphorylation, reduce Aβ-induced synaptic transmission damage, improve synaptic plasticity and significantly improve the cognitive function of AD mice, but its mechanism is unclear. In this study, 5xFAD transgenic mice and hippocampal neurons are used as the research objects, particle tracking and living cell imaging techniques are used to detect vesicle circulation process to clarify that daphnetin regulates vesicle redistribution; Genome-wide association study of daphnetin inhibiting phosphorylation of CaMKIV induced by Aβ and blocking synaptic vesicle transmission by transcriptome; RNAscope® and Western-blot techniques are used to elucidate whether daphnetin improves synaptic plasticity and cognitive dysfunction by inhibiting CaMKK-CaMKIV pathway, reducing Aβ-induced synaptic transmission damage and regulating vesicle redistribution. This topic will provide important experimental basis for daphnetin in the treatment of AD, and provide new ideas for exploring AD therapeutic drugs targeting at the repair of synaptic function.

认知功能障碍是阿尔茨海默症（AD）的主要临床表现，Aβ是引发突触功能障碍导致认知障碍极为重要的始动因子。减低Aβ对突触损伤、修复突触功能成为AD治疗的研究热点。我们前期研究发现：瑞香素可抑制CaMKIV磷酸化降低Aβ对突触传递损伤、提高突触可塑性进而显著改善AD小鼠认知功能，但其作用机制未明。本研究拟以5xFAD转基因小鼠及海马神经元为研究对象，运用粒子追踪及活细胞成像法检测囊泡循环过程以阐明瑞香素调节囊泡再分配的方式；运用转录组学对瑞香素抑制Aβ诱发CaMKIV磷酸化导致突触囊泡传递受阻进行全基因组关联研究通路分析；运用RNAscope®和western-blot等技术阐明瑞香素提高突触可塑性而改善认知功能障碍是否与抑制CaMKK-CaMKIV通路降低Aβ对突触传递损伤及调节囊泡再分配有关。本课题将为瑞香素治疗AD提供重要的实验依据，并为探究以突触功能修复为靶点的AD治疗药物提供新思路。

阿尔茨海默病是一种进行性神经退行性疾病，临床上以记忆和认知障碍为特征。大脑中Aβ积累被认为是AD发展的关键过程，它通过损害突触的功能从而损伤。本研究发现瑞香素可以减轻5xFAD转基因小鼠认知障碍。我们发现瑞香素可以通过降低BACE1表达增加ADAM17和ADAM10的表达来减少Aβ 的积累。电生理的实验结果显示瑞香素可以增加突触囊泡的释放以及增强LTP。同时，我们发现瑞香素可以通过激活PI3K-Akt-CREB-BDNF信号来减轻记忆障碍，促进树突分支密度并增加突触蛋白的表达。以上实验结果表明瑞香素可以通过减低Aβ对突触损伤，提高突触可塑性来改善AD小鼠的认知障碍。本课题实验结果为瑞香素治疗AD提供重要的实验依据，并为探究以突触功能修复为靶点的AD治疗药物提供新思路。此结果与预期结果一致。