Anesthetic Suppression of Memory through disinhibitory circuits in Hippocampus

 描述（由申请人提供）：该研究的长期目标是了解全身麻醉的机制，将特定的分子和细胞水平的目标与其网络和行为水平的后果联系起来。该建议的重点是海马GABAA受体在抑制学习和记忆的全身麻醉依托咪酯的作用。三个具体的目的测试的假设，依托咪酯块突触可塑性和记忆的靶向海马中的中间神经元，中断去抑制电路，这些过程是必不可少的。目的1）以GABAAR β2-N265 M突变小鼠为研究对象，探讨GABAAR β2亚基在依托咪酯抑制突触可塑性和记忆中的作用，并观察依托咪酯对LTP的影响。目的2）使用靶向所有中间神经元（GAD 65）或中间神经元的特定子集（VIP、CR、PV、CCK、SOM、O-LM）的Cre驱动线，确定从特定类别的中间神经元中去除α5-GABAAR是否干扰依托咪酯抑制突触可塑性和记忆的能力。目的3）研究依托咪酯对野生型和转基因小鼠去抑制回路的影响，从特定的中间神经元记录，以确定相关的抑制回路。 过程（即，纳入α5-和β2-GABAAR的那些），将我们的实验集中在那些被发现贡献最强的中间神经元类别上，并直接使用光遗传学方法操纵去抑制回路以再现或抵消 依托咪酯对LTP的影响。我们将学习的信息将有助于改进检测和治疗不良事件的方法，例如有时在麻醉后出现的意识回忆或持续记忆障碍。它还将帮助我们了解控制健康大脑学习和记忆的神经系统，这些系统在某些疾病状态下如何改变，以及如何操纵它们来改善患者的记忆。

 DESCRIPTION (provided by applicant): The long-term objective of the research is to understand the mechanism of general anesthesia, relating specific molecular- and cellular-level targets to their network- and behavioral-level consequences. This proposal focuses on the role of hippocampal GABAA receptors in the suppression of learning and memory by the general anesthetic etomidate. Three specific aims test the hypothesis that etomidate blocks synaptic plasticity and memory by targeting interneurons in the hippocampus, interrupting disinhibitory circuits that are essential to these processes. Aim 1) Test the role of GABAAR β2 subunits in suppression of synaptic plasticity and memory by etomidate, studying mice that carry the β2-N265M mutation and measuring the effects of etomidate on LTP in vitro and memory in vivo. Aim 2) Determine whether removing α5-GABAARs from specific classes of interneurons interferes with the ability of etomidate to suppress synaptic plasticity and memory, using Cre-driver lines targeting all interneurons (GAD65) or specific subsets of interneurons (VIP, CR, PV, CCK, SOM, O-LM). Aim 3) Measure the effects of etomidate on disinhibitory circuits in wild type and genetically modified mice, recording from specific interneurons to identify relevant inhibitory processes (i.e. those that incorporate α5- and β2-GABAARs), focusing our experiments on those classes of interneurons that are found to contribute most strongly, and manipulating disinhibitory circuits directly using optogenetic methods to reproduce or counteract the effects of etomidate on LTP in vitro and learning in vivo. The information that we will learn will aid in the development of improved methods for detecting and treating undesired events such as awareness with recall or persistent memory impairment that sometimes follows anesthesia. It also will help us understand the neural systems that are in place to control learning and memory in the healthy brain, how these systems are altered in certain disease states, and how they might be manipulated to improve memory in patients.