Mechanisms of pathway-specific plasticity in the incubation of craving

摘要 可卡因成瘾包括对吸毒失去控制，从而使个人随着时间的推移服用更多的药物和 即使在长期戒毒之后，也可能长期易再次吸毒。这个 这些变化背后的中枢神经系统神经元的进行性分子和突触适应并不是 很好理解，但可以使用基于扩展可卡因自我给药的动物模型进行研究 然后是大鼠的禁欲。这些模型已经表明，伏隔核核心(NACC)，一个小的 但腹侧纹状体的关键脑区与强迫性吸食可卡因和复吸可卡因有关 寻求长期禁欲。NACC接收和整合来自许多不同类型的传入信息 大脑区域，有两个主要的输出投射，直接和间接路径；这些路径倾向于 相互对立的功能，我们预测这些神经元内信号过程中的适应 是影响吸毒复发的关键决定因素。通过了解细胞中的适应 在广泛的可卡因暴露和戒断后，这些NACC输出神经元中的信号，我们希望 有助于制定新的治疗策略，以减少吸毒复发的可能性。 我们建议调查戒毒期间寻求药物的时间依赖性增加，称为 “渴望的孵化”。我们将使用几个创新工具。首先，我们将使用交叉型病毒载体 DREADDS等转基因蛋白的导入扰动及直接和间接研究方法 在孵化过程中选择性地传递神经元。通过向AAV载体注射丛生和倒置转基因 在NACC中，我们可以通过以下方式选择性地激活直接或间接途径神经元中的转基因表达 向腹侧被盖区或腹侧苍白球注射CAV2-CRE，该CAV2-CRE逆行输送到 NACC内的胞体。其次，我们将使用经过改造的“DREADD”受体，这是一项我们帮助 为在复杂的行为实验中用于大鼠大脑而建立。DREADD将允许我们激活Gs或 GI信号通路在直接或间接通路神经元中选择性地在 吸食可卡因或在早期或晚期强制戒断，从而评估这些典型的第二 信使通路调节升级或孵化过程中的可塑性。第三，我们将利用RiboTag 从直接或间接途径神经元中选择性免疫纯化多聚核糖体的技术研究 戒断和渴求孕育过程中这两条相反途径中RNA翻译的变化 在细胞体和突触中，局部蛋白质翻译的活性依赖变化 描述。通过干扰和测量特定神经元中的信号通路，我们希望开发出新的 改善与强迫性药物使用和复发寻求相关的适应的策略。

Abstract Cocaine addiction involves the loss of control over drug taking so that individuals take more drug over time and can have prolonged vulnerability to relapsing to drug seeking, even after extended periods of abstinence. The progressive molecular and synaptic adaptations in neurons in the CNS that underlie these changes are not well understood, but can be studied using animal models based on extended cocaine self-administration followed by abstinence in rats. These models have shown that the nucleus accumbens core (NAcC), a small but critical brain region in ventral striatum, is implicated in compulsive cocaine taking and relapse to cocaine seeking after extended abstinence. The NAcC receives and integrates afferent information from many different brain regions and has two main output projections, the direct and indirect pathways; these pathways tend to oppose one another functional, and we predict that adaptations in signaling processes within these neurons are critical determinants affecting the relapse to drug seeking. By understanding the adaptations in cell signaling in these NAcC output neurons following extensive cocaine exposure and abstinence, we hope to contribute to novel treatment strategies for reducing the potential for relapse to drug seeking. We propose to investigate the time-dependent increase in drug seeking during abstinence known as the “incubation of craving”. We will use several innovative tools. First, we will use an intersectional viral vector approach to introduce DREADDs and other transgenic proteins to perturb and study direct and indirect pathway neurons selectively during incubation. By injecting AAV vectors with floxed and inverted transgenes into NAcC, we can activate transgene expression selectively in the direct or indirect pathway neurons by injecting the ventral tegmental area or ventral pallidum with CAV2-Cre, which is retrogradely transported to the cell bodies in NAcC. Second, we will use engineered “DREADD” receptors, a technology that we helped to establish for use in rat brain during complex behavioral experiments. DREADDs will allow us to activate Gs or Gi signaling pathways selectively in either direct or indirect pathway neurons during either repeatedly during cocaine taking or during early or late forced abstinence, thereby assessing how these canonical second messenger pathways modulate the plasticity involved in escalation or incubation. Third, we will utilize RiboTag technology to immunopurify polyribosomes selectively from direct or indirect pathway neurons and investigate the changes in RNA translation in these opposing pathways during abstinence and incubation of craving, both in cell bodies and in the synapses where activity dependent changes in local protein translation has been described. By perturbing and measuring signaling pathways in specified neurons, we hope to develop new strategies for ameliorating the adaptations associated with compulsive drug use and relapse to seeking.