生理刺激条件下活体内AMPA受体动态变化和突触可塑性分子机制研究

In the central nervous system, ionotropic AMPA receptors (AMPARs) mediate the majority of the fast excitatory synaptic transmission, trafficking of AMPARs into and out of synapses is a highly dynamic process, which plays a critical role in synaptic plasticity and learning and memory. Thus understanding AMPAR trafficking and regulation is of utmost importance for understanding animal behavior and higher brain function. Previous in vitro studies have greatly advanced our knowledge in AMPAR trafficking and regulation, especially at the molecular level, however, how does AMPAR traffic and behave in live animals remains elusive. Utilizing in vivo two photon imaging, we were able to observe real time AMPAR dynamics in vivo for the very first time, our approach opens up a totally new way to study synaptic plasticity in vivo. Passive whisker stimulation and active whisking leads to very different sensory input, although our results showed passive stimulation leads to an increase in spine surface AMPARs, it is still not clear how does this relate to synaptic plasticity under physiological conditions. Therefore, elucidating the molecular mechanism underlying active whisking will improve our understanding of sensory perception. Here we plan to monitor in vivo AMPAR dynamics under multiple whisker stimulation paradigms, in the meantime, investigate neuronal activity using genetically encoded calcium indicators such as GCamp6. Our results will provide novel information for AMPAR trafficking and regulation and dramatically advance our understanding of higher brain functions such as sensory perception.

AMPA受体介导中枢神经系统中绝大部分的快速兴奋性突触传递，受体插入和离开突触的转运过程高度动态化，该过程的调节在突触可塑性以及学习和记忆中发挥关键作用。因此阐明AMPA受体转运和功能的调控对于理解大脑功能至关重要。大量体外研究已经在分子层面对AMPA受体的转运和调节有很好的诠释，然而动物活体内AMPA受体如何被转运仍未被阐明。利用双光子活体成像系统，申请人发现强烈的被动胡须刺激能引起 AMPA受体的动态变化，从而为突触可塑性的研究开辟了新途径。而被动胡须刺激与主动胡须应用所引起的信息输入大不相同，所以研究主动胡须移动的分子机制对于理解感官知觉更为重要。本课题将运用双光子成像监测主动胡须应用模式下活体内AMPA受体的动态变化，并利用遗传编码的钙指示剂研究神经元活性的变化。研究结果将明确活体内多种胡须刺激模式下AMPA受体转运规律和调控的分子机制从而使我们更深入地理解动物感觉认知等大脑功能。

AMPA受体介导中枢神经系统中绝大部分的快速兴奋性突触传递，受体插入和离开突触的转 运过程高度动态化，该过程的调节在突触可塑性以及学习和记忆中发挥关键作用。因此阐明AM PA受体转运和功能的调控对于理解大脑功能至关重要。利用双光子活体成像系统，申请人发现被动胡须刺激能引起 AMPA受体的动态变化，为突触可塑性的研究开辟了新途径。而主动胡须移动对AMPA受体的作用尚不清楚。我们研究发现丰富环境探索和胡须修剪对树突棘表面AMPA受体和树突棘大小有不同的影响，提示结构和功能可塑性在不同刺激条件下可以很好的分离。我们进一步揭示运动学习能引起运动皮层、视觉皮层等较为广泛的AMPA 受体上膜介导的突触增强，动物的学习行为需要多个脑区之间相互协同、相互作用。