Investigating the mechanistic contribution of Cav1.2 channels in extinction of cocaine-associated memories

项目摘要 可卡因成瘾给社会和个人带来了高昂的代价，到目前为止还没有药物疗法。 行为疗法在预防复发方面并不有效；事实上，70%-80%的可卡因吸毒者将经历 治疗后复发。预防再次吸食可卡因是存在的主要挑战 对可卡因依赖者的治疗。导致复发的众多因素之一是 滥用毒品，如可卡因，在环境背景之间产生的异常强烈的联系 以及这种药物的有益特性。因此，了解负责的神经机制 这些与药物相关的联系以及我们可以超越它们的方式，对于发展 改进了治疗方案。背侧海马体(DHPC)，以其在学习和记忆中的作用而闻名， 是一个与可卡因相关的重要解剖区域。尽管知道了这一点，但 关于可卡因成瘾的这一大脑区域的研究还很少。我们实验室的工作确定了一个新的角色 对于可卡因相关语境记忆消退的dHPC中的CAV1.2 L型钙通道， 与它们在某些形式的海马神经元依赖的突触可塑性中所起的众所周知的作用一致 学习/记忆。灭绝学习涉及一种新的学习形式，它能够超越原始 记忆，尤其是不适应的记忆。因此，Cav1.2通道是一个很有希望的候选通道 凌驾于毒品背景关联之上。使用可卡因条件性位置偏爱(CPP)，一个临床前模型 用来研究与可卡因相关的背景记忆，我们发现可卡因CPP的消退增加 CAV1.2及其磷酸化形式在海马背齿状回的突触表达 亚区，以多巴胺D1受体细胞类型依赖的方式。这与越来越多的证据表明 DHPC多巴胺在学习/记忆机制中的作用，包括可卡因背景记忆。我们的 分子研究已经证实，灭绝会增加DDG中的关键信号分子。这些措施包括 AKAP150锚定蛋白、PKA、NFATc3和AMPA受体的GluA1亚基。因此，在此应用程序中 我们的目标是利用这些知识来进一步探索DDG Cav1.2在灭绝中的渠道机制 与可卡因相关的记忆。我们将验证这样一个中心假设，即情境消亡学习会招募 Cav1.2通过招募多巴胺D1R信号在DDG突触上的通道机制。我们将使用组合 遗传学、药理学、电生理学和活体钙成像技术与行为测试 进行拟议的研究。AIM 1将测试AKAP-PKA-Cav1.2信号的参与情况。目标2将解决 AKAP-CAN-NFAT信号和AIM 3的参与将检验D1R信号在可卡因中的作用 CPP消退和DDG细胞活性。

Project Summary Cocaine addiction exerts a high cost on society and individuals and to date no pharmacotherapies exist. Behavioral therapies are not effective at preventing relapse; indeed, 70-80% of cocaine users will experience relapse following therapy. Preventing relapse to cocaine use represents the primary challenge that exists for the treatment of cocaine dependent individuals. One of the many factors that contribute to relapse is the exceptionally strong associations that drugs of abuse, such as cocaine make between environmental contexts and the rewarding properties of the drug. Thus, understanding the neural mechanisms that are responsible for these drug-context associations and ways in which we can override them, is critical for the development of improved treatment options. The dorsal hippocampus (dHPC), well known for its role in learning and memory, is an important anatomical region involved in cocaine-context associations. Despite this knowledge, the role of this brain region in cocaine addiction remains understudied. Work from our laboratory has identified a novel role for the Cav1.2 L-type Ca2+ channel (LTCC) in the dHPC in extinction of cocaine-associated contextual memories, consistent with their well-known role in hippocampal-dependent synaptic plasticity underlying certain forms of learning/memory. Extinction learning involves a new form of learning that is capable of overriding original memories, particularly maladaptive memories. Thus Cav1.2 channels serve as a promising candidate for overriding drug-context associations. Using the cocaine conditioned place preference (CPP), a preclinical model used to study cocaine-associated contextual memories, we find that extinction of cocaine CPP increases synaptic levels of Cav1.2 and its phosphorylated form in the dorsal dentate gyrus (dDG), a hippocampal subregion, in a dopamine D1 receptor cell type-dependent manner. This is consistent with growing evidence for a role of dHPC dopamine for learning/memory mechanisms including cocaine contextual memories. Our molecular studies have identified that extinction increases key signaling molecules in the dDG. These include AKAP150 anchoring protein, PKA, NFATc3 and the GluA1 subunit of AMPA receptors. Thus, in this application we aim to capitalize on this knowledge to further explore dDG Cav1.2 channel mechanisms in extinction of cocaine-associated memories. We will test the central hypothesis that contextual extinction learning recruits Cav1.2 channel mechanisms at dDG synapses via recruiting dopamine D1R signaling. We will use a combination of genetic, pharmacological, electrophysiological, and in vivo calcium imaging techniques with behavioral testing for the proposed studies. Aim 1 will test the involvement of AKAP-PKA-Cav1.2 signaling. Aim 2 will address the involvement of AKAP-CaN-NFAT signaling and Aim 3 will examine the contribution of D1R signaling, in cocaine CPP extinction and dDG cell activity.