Anesthetic Suppression of Memory through disinhibitory circuits in Hippocampus

 描述(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靶点与其网络和行为水平的后果联系起来。这项建议侧重于海马区GABAA受体在全麻药依托咪酯抑制学习和记忆中的作用。三个特定的目标测试了依托咪酯通过靶向海马区的中间神经元，中断对这些过程至关重要的去抑制电路来阻止突触可塑性和记忆的假设。目的1)检测β2亚单位在依托咪酯抑制突触可塑性和记忆中的作用，以携带β2-N265M突变的小鼠为研究对象，检测依托咪酯对突触可塑性和体内记忆的影响。目的2)使用针对所有中间神经元(GAD65)或中间神经元特定亚群(α、CR、PV、CCK、SOM、O-LM)的CRE驱动器线，确定从特定类别的中间神经元去除CCK5-GABAARs是否干扰依托咪酯抑制突触可塑性和记忆的能力。目的3)检测依托咪酯对野生型和转基因小鼠去抑制环路的影响，从特定的中间神经元记录以确定相关的抑制 过程(即那些包含α5-和β2-GABAARs的过程)，我们的实验集中在那些被发现贡献最大的一类中间神经元上，并直接使用光遗传学方法操纵去抑制电路，以再现或抵消 依托咪酯对LTP的体外和体内学习作用。我们将学到的信息将有助于开发改进的方法来检测和治疗不良事件，如意识与回忆或有时伴随麻醉的持久性记忆障碍。它还将帮助我们了解控制健康大脑中学习和记忆的神经系统，这些系统在某些疾病状态下是如何改变的，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.