基于突触后膜受体调控的开心散改善Aβ所致突触可塑性抑制的机制研究

Aβ plays an important role in pathogenesis of AD. We have found that soluble Aβ injured memory ability seriously early before senile plaque formation. However, it’s still lack of effective medicine in treating AD to date. Recently, our study indicates that the Chinese classic formula KXS could improve LTP inhibition induced by Aβ significantly through the postsynaptic mechanism. And the degree of memory injury is positive related with the LTP inhibition degree. The change of AMPA receptors expression on postsynaptic surface is the neurobiological basis of memory formation. These results suggest that KXS improving memory injury induced by Aβ based on enhancing modulating postsynaptic membrane receptor function. In view of our previous studies, we will combine electrophysiological, histological and molecular biological methods to explore the mechanism of KXS improving memory function. We would detect on the related receptor proteins level of postsynaptic membrane and primary hippocampal neurons in the state of LTP inducing in vivo and vitro. Also, the mice memory function would be observed by behavioral test. We will focus on analyzing the relationship between modulation of postsynaptic membrane receptors and synaptic plasticity formation and these how to act on memory formation, the neurobiological mechanisms of KXS improving synaptic plasticity inhibition induced by Aβ based on postsynaptic membrane receptors modulation would be demonstrated. This study will provide new thoughts for the exploration of treatment medicine in AD. Importantly, it will bring vast development prospect for AD treated by TCM and the clinical apply for KXS.

Aβ是阿尔茨海默病（AD）发病的关键蛋白，课题组早期工作证明在老年斑形成前可溶性Aβ就已损害记忆功能，而我们近期研究表明，中医古典方剂开心散通过突触后膜机制改善Aβ诱发的LTP抑制，且记忆损害程度与LTP抑制程度呈正相关，膜表面AMPA受体表达的改变是记忆形成的神经生物学基础，提示开心散可能通过调节突触后膜表面受体功能改善Aβ诱发的记忆损害，但机制尚不清楚。本课题拟在前期工作基础上，应用电生理学、组织学及分子生物学技术相结合的手段，探索开心散改善记忆功能的机制。将通过在体和离体方法在LTP诱发状态下，检测突触后膜表面受体调控相关蛋白表达及海马神经元AMPA受体动态变化，同时通过行为学手段监测动物记忆功能。分析突触后膜表面受体及其调控与突触可塑性形成的相关性，及与记忆形成的关系，阐明开心散改善Aβ诱发突触可塑性抑制的神经生物学机制。本课题将为AD的中医药治疗及开心散的临床应用提供实验依据。

膜表面AMPA受体在记忆形成中起关键作用，本项目针对开心散可改善AD模型的记忆障碍这一功效，从整体、组织、细胞、分子等方面对其进行了作用靶点和机制的研究。研究结果表明：在体电生理学实验证实开心散可改善Aβ诱发的LTP抑制，而这是开心散改善Aβ诱发记忆障碍的机制之一。利用分子生物学技术揭示了开心散通过①增加GLUR1 Ser845位点的磷酸化，②降低GLUR2 Ser880位点的磷酸化，③增加ABP、GRIP和NSF蛋白的表达以增加膜表面AMPAR的锚定，④增加CaMKⅡ的表达以增加膜表面AMPAR的外插，进而增加突触后膜表面AMPAR蛋白的表达，从而改善Aβ对LTP的抑制。利用RT-PCR技术证实开心散增加GLUR2 mRNA的表达，这可能是GLUR2蛋白表达增加的原因之一。而体外实验证实了开心散的神经元保护作用。本研究揭示了开心散防治AD的作用靶点及机制，有助于为开心散的临床应用提供依据并为经方的研究提供思路。