The role of GIRK3 in ethanol withdrawal-induced changes in learning and memory

描述(申请人提供)：酒精成瘾是最常见的成瘾障碍之一，在正在康复的酗酒者中复发率很高。戒酒后成瘾的发展和随后的复发与几个有助于学习和记忆的过程和神经结构有关，多项研究表明，酒精成瘾可能是一种不适应学习的形式。酒精戒断的严重程度是成瘾发展的一个指标，也是复发的一个主要因素。我们的实验室最近发现Kcnj9是一个与小鼠酒精戒断有关的数量性状基因(QTG)。Kcnj9编码G蛋白偶联内向整流钾(GIRK)通道家族的GIRK3/Kir3.3亚单位，GIRK3基因敲除(KO)和杂合子(HET)小鼠表现出较不严重的酒精戒断。此外，GIRK通道调节长时程增强，这是一种学习和记忆的细胞机制。本研究的目的是评估GIRK3在恐惧条件性学习和记忆中的作用，并确定GIRK3表达的变化是否会改变戒断诱导的恐惧条件性反应的变化。该项目的长期目标还包括研究GIRK3在个体学习中的作用 相关的大脑区域。在目标1中，GIRK3 KO、HET和野生型(WT)产仔将在急性酒精戒断和对照动物中使用两种恐惧条件反射范式(延迟恐惧条件作用和痕迹恐惧条件作用)进行训练。这两种形式的条件性学习被认为利用不同但重叠的神经底物，使我们能够评估不同学习相关脑区GIRK3表达减少的影响。训练结束后，动物将根据训练环境和条件性刺激进行冰冻评估。在目标2中，将使用这两种恐惧条件反射类型对慢性酒精戒断后的动物进行训练，使我们能够比较不同形式的酒精戒断对学习和记忆的影响。这些目的不仅将决定GIRK3通道在恐惧条件性学习和记忆中的作用，还将表征酒精戒断对学习和记忆的影响，以及GIRK3的学习效应和减少戒断效应之间的重叠程度。第三个目标将使用目标1和目标2的结果来识别特定的大脑区域，这些区域与戒断严重程度的改变和在这些GIRK3基因中观察到的学习/记忆变化有关。我们将使用RNAi来下调WT小鼠单个脑区GIRK3的表达，并评估这种下调对酒精戒断和相关学习和记忆变化的减弱能力。总体而言，这项工作将有助于我们理解乙醇如何改变学习和记忆系统，这是成瘾发展和复发的一个关键方面。 公共卫生相关性：酒精成瘾的发展和戒酒者的高复发率与酒精引起的学习和记忆系统的变化有关。虽然学习/记忆和酒精成瘾都是由多种遗传和环境因素导致的复杂过程，但有几个小组报告说，这两组行为的染色体区域重叠。该项目使用一种新的戒酒遗传模型来研究戒酒引起的基于恐惧的学习和记忆的变化。

DESCRIPTION (provided by applicant): Alcohol addiction is one of the most common addictive disorders with a high rate of relapse among recovering alcoholics. The development of addiction and subsequent relapse following abstinence have been linked to several of the processes and neural structures that contribute to learning and memory, and multiple lines of research suggest that alcohol addiction may be a form of maladaptive learning. Ethanol withdrawal severity is an indicator of addiction development and a major factor in relapse. Our lab recently identified Kcnj9 as a quantitative trait gene (QTG) for ethanol withdrawal in mice. Kcnj9 codes for the GIRK3/Kir3.3 subunit of the G- protein coupled inwardly rectifying potassium (GIRK) channel family, and GIRK3 knockout (KO) and heterozygote (HET) mice show less severe ethanol withdrawal. In addition, GIRK channels modulate long-term potentiation, a cellular mechanism of learning and memory. The goal of the current proposal is to assess the role of GIRK3 in fear-conditioned learning and memory and determine if changes in GIRK3 expression alter the withdrawal-induced changes in fear conditioning responses. The long-term goals of this project also include investigating the role of GIRK3 in individual learning related brain regions. In Aim 1, GIRK3 KO, HET, and wildtype (WT) littermates will be trained using two fear conditioning paradigms (delay fear conditioning and trace fear conditioning) in acute ethanol withdrawn and control animals. These two forms of conditioned learning are thought to utilize distinct but overlapping neural substrates, allowing us to assess the effect of reduced GIRK3 expression in different learning-related brain regions. After training, animals will be assessed for freezing in response to the training context and the conditioned stimulus. In Aim 2, animals will be trained following chronic ethanol withdrawal using these two fear conditioning types, allowing us to compare the effects of GIRK3 expression on learning and memory across multiple forms of ethanol withdrawal. These aims will not only determine the role of GIRK3-containing channels in fear conditioned learning and memory, but also characterize the effect of alcohol withdrawal on learning and memory and the extent of overlap between the learning effects and the withdrawal-reducing effects of GIRK3. The third aim will use the results from Aims 1 and 2 to identify specific brain regions that contribute to the altered withdrawal severity and the learning/memory changes observed in these GIRK3 genotypes. We will use RNAi to knock-down GIRK3 expression in individual brain regions of WT mice and assess the ability of the knock-down to attenuate ethanol withdrawal and related changes in learning and memory. Overall, this work will contribute to our understanding of how ethanol alters learning and memory systems, a key aspect of addiction development and relapse. PUBLIC HEALTH RELEVANCE: The development of alcohol addiction and the high rate of relapse in recovering alcoholics have been linked to alcohol-induced changes in learning and memory systems. While both learning/memory and alcohol addiction are complex processes that result from multiple genetic and environmental factors, several groups have reported overlapping contributing chromosomal regions for these two groups of behaviors. This project uses a novel genetic model of alcohol withdrawal to investigate withdrawal-induced changes in fear-based learning and memory.