Molecular and circuit-level synergies in decision-making after early-life cocaine

描述（由申请人提供）：青春期是一个神经生物学上独特的发育时期，其特征是高比例的实验性药物使用和易受药物滥用的影响。青少年药物滥用增加了发展终身成瘾的可能性，可卡因成瘾的出现特别明显，例如，15-16%的青少年可卡因使用者将在第一次接触可卡因后的10年内产生依赖性。因此，确定可卡因脆弱性的机制是一项至关重要的研究任务。 可卡因和其他安非他明类精神兴奋剂有效地调节前额叶皮层的树突棘形态。可卡因暴露对神经结构的长期影响是否与青少年的脆弱性有因果关系，这在该领域引起了激烈的争论，但支持任何单一立场的直接证据是有限的。这部分是因为很少有实验室配备有工具来模拟动物系统中的成瘾，捕捉和计数树突棘结构，并操纵树突棘结构的分子调节器以分离因果关系。我们将开发和完善工具，以确定可卡因诱导的树突棘重组对决策和可卡因脆弱性的影响，目的是扭转早期可卡因暴露的不良后果。 在整个过程中，我们将重点放在1-整合素系统。1-整联蛋白是细胞外基质蛋白的受体，它与人类的可卡因成瘾有关。由于在整个中枢神经系统中广泛表达，1-整合素在开发成瘾治疗中是一个不切实际的目标;然而，其在皮质神经元中的下游效应子p190 RhoGAP提供了一个有希望的干预目标。p190 RhoGAP通过抑制肌动球蛋白收缩直接稳定前额叶皮质细胞结构，并通过增加脑源性神经营养因子（BDNF）的mRNA表达间接稳定前额叶皮质细胞结构。因此，我们建议开发工具来：1）使用病毒载体方法在体内抑制p190 RhoGAP功能。这比现有的工具（p190 rhogap杂合小鼠）有了重大的进步，现有的工具缺乏解剖学和时间选择性。 2)选择性操纵高亲和力BDNF受体trkB。这是必不可少的，因为尽管BDNF与成瘾病因学有关，但其受体靶点仍然未知。尽管最近开发了一种脑渗透trkB激动剂，在其他精神健康领域具有类似治疗的益处。 3)逆转早期接触可卡因的不良后果。我们将开发作用于肌动蛋白细胞骨架（如BDNF-trkB系统）而不是传统神经递质靶点的药理学干预措施。我们将这些工具应用于青春期服用可卡因的小鼠，目的是阻止成年后的适应不良决策。我们将使用高分辨率共聚焦显微镜来确定棘结构和行为结果之间的相关关系，并通过改进技术来直接操纵体内树突棘结构来确定因果关系。

DESCRIPTION (provided by applicant): Adolescence is a neurobiologically distinct developmental period characterized by high rates of experimental drug use and vulnerability to the development of substance abuse. Adolescent substance abuse increases the likelihood of developing lifelong addiction, and cocaine addiction emerges with particular virulence-for example, 15-16% of adolescent cocaine users will develop dependence within 10 years of first exposure. Thus, identifying mechanisms of cocaine vulnerability is a critical research imperative. Cocaine and other amphetamine-like psychostimulants potently regulate dendritic spine morphology in the prefrontal cortex. Whether the long-term consequences of cocaine exposure on neural structure are causally related to adolescent vulnerabilities represents a lively debate in field, however direct evidence supporting any single position is limited. This is in part becaus few labs are equipped with the tools to model addiction in animal systems, to capture and enumerate dendritic spine structure, and to manipulate the molecular regulators of dendritic spine structure to isolate causal relationships. We will develop and refine tools by which to identify the impact of cocaine-induced dendritic spine reorganization on decision-making and cocaine vulnerability with the goal of reversing the adverse consequences of early-life cocaine exposure. Throughout, we will focus on ¿1-integrin systems. ¿1-integrin is a receptor for extracellular matrix proteins, and it is implicated in cocaine addiction in humans. Because of widespread expression throughout the CNS, ¿1-integrin is an unrealistic target in developing treatments for addiction; however its downstream effector in cortical neurons, p190RhoGAP, offers a promising target for intervention. p190RhoGAP stabilizes prefrontal cortical cell structure directly by inhibiting actomyosin contraction and indirectly by increasing mRNA expression of Brain-derived neurotrophic factor (Bdnf). Therefore, we propose to develop tools to: 1) inhibit p190RhoGAP function in vivo using viral vector approaches. This presents a significant advance beyond existing tools (the p190rhogap heterozygous mouse), which lack anatomical and temporal selectivity. 2) selectively manipulate the high-affinity BDNF receptor, trkB. This is essential because although BDNF is implicated in addiction etiology, its receptor target in this context remains unknown. This is despite the recent development of a brain-penetrant trkB agonist with therapeutic-like benefits in other mental health domains. 3) pharmacologically reverse the adverse consequences of early-life cocaine exposure. We will develop pharmacological interventions that act on regulators of the actin cytoskeleton (such as BDNF-trkB systems) rather than traditional neurotransmitter targets. We will apply these tools to mice administered cocaine in adolescence with the goal of blocking maladaptive decision-making in adulthood. We will identify correlative relationships between spine structure and behavioral outcomes using high-resolution confocal microscopy, and causal relationships by refining techniques by which to directly manipulate dendritic spine structure in vivo.