Brain Structure & Function after Fetal Cocaine Exposure

描述(由申请人提供)： 我们研究计划的长期目标是确定孕期 可卡因暴露改变了神经回路的发展历程， 调节认知、情绪和奖励系统。静脉注射小剂量可卡因 给怀孕兔注射可通过以下方式促进树突状细胞生长 皮质投射神经元与钙结合蛋白表达增加 通过中间神经元。DA_1受体偶联显著减少。 其各自的G蛋白，导致D1R介导的永久性丢失 回应。缺陷主要发生在致密的多巴胺(DA)区域 神经支配，如前扣带回和纹状体。的开始 变化在胚胎中发生，并在成年后持续存在，在许多方面模仿 感受器丢失。我们对D1受体基因敲除小鼠的初步研究揭示 在ACC神经元发育中也有类似的异常。数据表明，这种变化 在D1R中，受体信号启动了一系列改变，导致 前脑回路发育异常。因此，产前药物暴露 和遗传模型都提供了独特的机会来理解 物质滥用对前脑发育的影响。研究将探索 细胞和分子适应的潜在机制。此外，我们 将测试这些适应如何改变未来中枢神经系统对可卡因和 特定的应激源，如谷氨酸兴奋性毒性。三个实验 特定的目标将使用生化。神经解剖学和分子生物学方法 解决这些假设。在目标1中，我们将研究细胞信号的变化 通过在子宫内接触可卡因改变树突生长。我们会 分析组成蛋白的磷酸化状态的变化 DA和谷氨酸信号系统的融合。D1R解偶联可能是 由受体交易的变化引起。实验将检查异常情况 多巴胺受体的细胞质隔离。 更具体地说，将DA受体功能障碍与发育 将在d1-i-小鼠和兔身上检查异常变化。 用直接的D1激动剂进行妊娠期治疗。在Aim 2中，实验将 研究子宫内可卡因暴露通过何种机制扰乱 中间神经元的发育。神经解剖学分析将确定d1是否 中间神经元特定亚群的受体共表达定义了 对妊娠可卡因最敏感的细胞。细胞内染料标记的研究 中间神经元将被用来分析在某些情况下树突的发育。 多巴胺受体功能障碍。在目标3中，将使用两种实验方法 为了研究产前首次接触可卡因的中枢神经系统对 后来接触可卡因或兴奋毒性侮辱。首先，利用基因芯片， 我们将确定在转录反应中的差异是由 可卡因对正常和实验兔的挑战。第二，兴奋性毒性 正常和暴露于可卡因的动物分离的神经元的反应性 在基于细胞的分析中进行研究。跨学科的方法将 定义产前引起的大脑结构和分子适应的变化 可卡因暴露，最终目标是设计干预措施， 改善药物暴露的长期行为后果。

DESCRIPTION (Provided by applicant): The long-term goals of our research program are to determine how gestational cocaine exposure changes the course of development of neural circuits that mediate cognitive, emotional and reward systems. Intravenous, low dose cocaine administration to pregnant rabbits results in enhanced dendritic growth by cortical projection neurons and increased expression of a Ca++-binding protein by interneurons. There is a striking reduction in DA D1 receptor coupling to its respective G-protein, resulting in a permanent loss of D1 receptor-mediated responses. Defects occur predominantly in regions of dense dopamine (DA) innervation, such as anterior cingulate cortex (ACC) and striatum. The onset of changes occurs embryonically and persists in the adult, in many ways mimicking receptor loss. Our preliminary studies in the D1 receptor knockout mouse reveal similar abnormalities in ACC neuron development. The data suggest that changes in D1 receptor signaling initiate a cascade of alterations that results in abnormal development of forebrain circuits. Thus, the prenatal drug exposure and genetic models each provide unique opportunities for understanding the impact of substance abuse on forebrain development. Studies will probe mechanisms underlying the cellular and molecular adaptations. In addition, we will test how these adaptations alter future CNS responsiveness to cocaine and specific stressors, such as glutamate excitotoxicity. Experiments in three specific aims will use biochemical. neuroanatomical and molecular approaches to address the hypotheses. In Aim 1, we will investigate changes in cell signaling through which in utero cocaine exposure alters dendritic growth. We will analyze alterations in the phosphorylation state of proteins comprising the converging DA and glutamate signaling systems. D1 receptor uncoupling could be caused by changes in receptor trafficking. Experiments will examine aberrant cytoplasmic sequestration of DA receptors. To more specifically link DA receptor dysfunction to developmental abnormalities changes will be examined in the D1 -I- mouse and in rabbits treated gestationally with a direct D1 agonist. In Aim 2 experiments will investigate the mechanisms through which in utero cocaine exposure disrupts the development of interneurons. Neuroanatomical analysis will establish whether D1 receptor co-expression by specific subpopulations of interneurons defines the cells most susceptible to gestational cocaine. Intracellular dye labeling of interneurons will be used to analyze dendritic development under circumstances of DA receptor dysfunction. In Aim 3, two experimental approaches will be used to investigate how the CNS, first exposed to cocaine prenatally, responds to later cocaine exposure or excitotoxic insults. First, using gene microarrays, we will determine differences in transcriptional responses that are induced by cocaine challenges in normal and experimental rabbits. Second, the excitotoxic responsiveness o isolated neurons from normal and cocaine-exposed animals will be investigated in cell-based assays. The interdisciplinary approaches will define alterations in brain structure and molecular adaptations due to prenatal cocaine exposure, with a goal ultimately to design interventions that may ameliorate the long-term behavioral consequences o drug exposure.