Neuronal ensembles of drug context-induced impulsive decision making

描述（由申请人提供）：高冲动性与可卡因成瘾者对药物依赖、药物复发和治疗失败的脆弱性有关。使用一种新的动物模型，我们的实验室已经证明，值得注意的是，单独暴露于可卡因配对的环境背景下会产生一种增加的冲动状态，表现为更大的延迟折扣行为（即，选择一个小的立即可用的奖励超过一个较大的奖励可用的时间延迟）在可卡因配对的背景下比在未配对的控制背景下[11]。基于额外的令人兴奋的初步数据和现有的冲动性文献，所提出的探索性R21项目将测试总体假设，即外侧眶额皮质（IOFC）内的不同神经元集合促进，而在前边缘皮质（PrL）中反对，药物情境诱导的冲动决策（DCIDM）。此外，DCIDM的双向调节产生于暴露于可卡因配对环境时这些神经元集合内的兴奋性投射神经元和GABA能中间神经元的差异激活。具体目标1将是检验IOFC和PrL中的药物背景激活的神经元集合分别对于促进和抑制DCIDM至关重要的假设。实验将使用Daun 02药物遗传学方法在c-fos-lacZ转基因大鼠中的IOFC或PrL内位点选择性地损伤推定的可卡因上下文激活的神经元系综。我们将评估这些操作对可卡因配对或未配对对照背景下延迟折扣行为的影响。我们预测，可卡因上下文反应性的LOFC神经元集合的病变将抑制，而可卡因上下文反应性的PRL神经元集合的病变将增强DCIDM。具体目标2将是表征在c-fos-lacZ转基因大鼠中调节DCIDM的神经元系综内药物环境激活的神经元亚群的表型。我们将使用双标记免疫组织化学和共聚焦显微镜来定量目标1中大鼠脑中Daun 02保留的Fos/CaMK II和Fos/GAD 67免疫反应（IR）细胞体。我们预测，暴露于可卡因配对的情况下，elevenly优先兴奋性神经元激活的th 1 OFC，和优先GABA能神经元激活的PrL，感兴趣的神经元合奏。这将通过Daun 02诱导的OFC中的优先Fos/CaMKII-IR细胞损失和PrL中的优先Fos/GAD 67-IR细胞损失来反映，在DCIDM测试期间可卡因配对背景暴露后收集的组织中。总的来说，这个R21项目将探索新发现的DCIDM现象的神经生物学基础，使用新的动物模型，最先进的药物遗传学技术和双标记免疫组织化学共聚焦显微镜。这种高风险/高收益的建议有可能启动一个新的调查线，提供原始的洞察可卡因滥用冲动决策的后果，并告知可卡因成瘾治疗的发展。

DESCRIPTION (provided by applicant): High impulsivity is associated with vulnerability to drug dependence, drug relapse, and treatment failure in cocaine addicts. Using a novel animal model, our laboratory has demonstrated that, remarkably, exposure to a cocaine-paired environmental context alone produces a state of increased impulsivity, indicated by greater delay discounting behavior (i.e., choice of a small immediately available reward over a larger reward available with a time delay) in a cocaine-paired context than in an unpaired control context [11]. Based on additional exciting preliminary data and the existing impulsivity literature the proposed exploratory R21 project will test the overarching hypothesis that distinct neuronal ensembles within the lateral orbitofrontal cortex (lOFC) promote, whereas in the prelimbic cortex (PrL) oppose, drug context-induced impulsive decision making (DCIDM). Furthermore, bidirectional regulation of DCIDM arises from the differential activation of excitatory projection neurons and GABAergic interneurons within these neuronal ensembles upon exposure to the cocaine-paired context. Specific Aim 1 will be to test the hypothesis that drug context-activated neuronal ensembles in the lOFC and PrL are critical for promoting and suppressing DCIDM, respectively. Experiments will use the Daun02 pharmacogenetic method to site-selectively lesion putative cocaine context-activated neuronal ensembles within the lOFC or PrL in c-fos-lacZ transgenic rats. We will evaluate the effects of these manipulations on delay discounting behavior in the cocaine-paired or an unpaired control context. We predict that lesion of cocaine context-reactive lOFC neuronal ensembles will inhibit, whereas lesion of cocaine context-reactive PrL neuronal ensembles will potentiate DCIDM. Specific Aim 2 will be to characterize the phenotype of drug context-activated neuronal subpopulations within the neuronal ensembles that regulate DCIDM in c-fos-lacZ transgenic rats. We will use double-label immunohistochemistry with confocal microscopy to quantify Fos/CaMKII- and Fos/GAD67-immunoreactive (IR) cell bodies spared by Daun02 in the brains of rats from Aim 1. We predict that exposure to a cocaine-paired context elicits preferential excitatory neuronal activation in th lOFC, and preferential GABA-ergic neuronal activation in the PrL, neuronal ensembles of interest. This will be reflected by Daun02-induced preferential Fos/CaMKII-IR cell loss in the OFC and preferential Fos/GAD67-IR cell loss in the PrL, in tissue collected after cocaine-paired context exposure during the DCIDM test. Overall, this R21 project will explore the neurobiological underpinnings of the newly discovered DCIDM phenomenon using a novel animal model, state-of-the-art pharmacogenetic techniques, and double-label immunohistochemistry with confocal microscopy. This high risk/high gain proposal has the potential to initiate a new line of investigation, provide original insight into the consequences o cocaine abuse on impulsive decision making, and inform the development of treatments for cocaine addiction.