基于内嗅皮层-海马CA1神经环路探讨电针改善AD模型小鼠空间记忆功能的作用及其机制

The entorhinal cortex-hippocampal CA1 neural circuit dysfunction plays a key role in spatial memory after Alzheimer's disease (AD). Thus, to improve the function of neural circuit is a crucial target to prevent and treat AD. Our previous studies have demonstrated that electroacupuncture (EA) at Baihui and Shenting acupoints can ameliorate neuronal activity from entorhinal cortex and hippocampus CA1 regions in a rat model of cerebral ischemia. Therefore, we speculate that EA at Baihui and Shenting acupoints may strengthen spatial memory ability in AD model mice via regulating the entorhinal cortex-hippocampal CA1 neural circuit. In this study, an AD induced spatial memory deficit mice model will be established. Optogenetic and chemogenetic strategies will be conducted to activate and suppress the neuronal activity of entorhinal cortex and hippocampus CA1. Observation and analysis of animal behavioral test, animal MRI and PET will be used to uncover the role of entorhinal cortex-hippocampal CA1 neural circuit in EA ameliorating spatial memory deficit of AD model mice. As well as the structure of circuits will be revealed by using neurotropic trans-synaptic virus tracers. Furthermore, plasticity changes on glutamate synapse detected by LTP/LTD and underlying molecular mechanism mediated by NMDA/AMPA receptors in entorhinal cortex-hippocampal CA1 neural circuit will be illuminated by using electrophysiology and molecular biology technologies. The expected results of this study will help to further understand the mechanism of EA in treating AD, as well as to provide sound experiment evidence for clinical acupuncture practice.

内嗅皮层-海马CA1神经环路异常是影响阿尔茨海默病（AD）空间记忆功能障碍的关键因素，如何改善其功能成为防治AD的靶标。前期我们证实电针百会、神庭穴可激活脑缺血模型大鼠内嗅皮层、海马CA1区神经细胞活动。因此，我们推测电针百会、神庭穴可以调控AD模型小鼠内嗅皮层-海马CA1神经环路功能进而改善空间记忆功能。本课题拟从AD模型小鼠空间记忆功能损伤的角度，通过光/化学遗传学技术激活、抑制内嗅皮层或海马CA1，结合动物行为学测试、小动物MRI和PET的观察探讨内嗅皮层-海马CA1神经环路在电针改善空间记忆功能中的关键作用，并利用跨突触嗜神经病毒示踪揭示其环路结构完整性。进一步利用电生理和分子生物学技术阐明内嗅皮层-海马CA1神经环路突触发生LTP/LTD的可塑性变化及其NMDA/AMPA受体介导的可能分子机制，所获得的结果有助于更深入了解电针治疗AD的作用机制，为临床针刺应用提供可靠的实验依据。

空间记忆障碍是阿尔茨海默病早期常见症状之一，内嗅皮层与海马之间存在纤维投射，构成内嗅皮层-海马神经环路，对于空间学习记忆和空间定位起着重要作用。已有大量文献证实针刺可有效改善阿尔茨海默病早期认知功能障碍，但其作用机制尚未明确。本课题利用新物体识别、水迷宫测试揭示了电针百会、神庭可以延缓AD模型小鼠的空间学习记忆功能；利用小动物静息态功能磁共振成像发现电针后AD模型小鼠脑区包括双侧海马、右侧内嗅皮层、右侧感觉皮层、双侧海马下托、右侧颞叶皮层局部一致性升高，进一步弥散张量扫描观察发现电针干预增加了内嗅皮层和海马脑区之间的纤维连接；利用化学遗传系统与电生理系统验证了内嗅皮层-海马神经环路兴奋性活动在电针百会、神庭穴改善AD小鼠空间记忆功能中的作用；阐明了电针可提高AD小鼠内嗅皮层-海马神经环路兴奋性活动，可能通过降低了tau蛋白磷酸化水平(主要包括AT8、S422和S262)，以及增强NMDA受体表达、CaMKⅡ与CREB磷酸化诱导的突触可塑性，促进内嗅皮层和海马树突棘形态的修复、易化内嗅皮层-海马CA1的LTP反应。所获得研究结果为电针治疗阿尔茨海默病早期空间记忆功能提供重要的实验依据。本课题已发表SCI论文3篇，中文核心期刊4篇，在投SCI论文1篇。培养了博士研究生1名、硕士研究生2名，课题负责人入选国际欧亚科学院院士与国家中医药传承与创新“百千万”人才工程“岐黄学者”。