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妊娠期 可卡因暴露会改变神经回路的发育过程， 调节认知、情感和奖励系统。静脉注射低剂量可卡因 对怀孕的兔子给药， 皮质投射神经元和Ca ++结合蛋白表达增加 通过interneurons。DA D1受体偶联到 其各自的G蛋白，导致D1受体介导的 应答缺陷主要发生在多巴胺（DA）密集区域 神经支配，如前扣带皮层（ACC）和纹状体。的发作 变化发生在胚胎期，并持续到成年，在许多方面模仿 受体丧失我们在D1受体敲除小鼠中的初步研究显示， ACC神经元发育的类似异常。数据显示， 在D1受体信号传导中启动了级联的改变， 前脑回路的异常发展。因此，产前药物暴露 和遗传模型都提供了独特的机会， 药物滥用对前脑发育影响。研究将探讨 细胞和分子适应的潜在机制。另外我们 将测试这些适应如何改变未来中枢神经系统对可卡因的反应， 特定的应激源，如谷氨酸兴奋毒性。实验三 具体目标将使用生物化学。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传导的变化 子宫内可卡因暴露通过其改变树突生长。我们将 分析蛋白质磷酸化状态的改变，所述蛋白质包括 聚合多巴胺和谷氨酸信号系统。D1受体解偶联可能是 由受体运输的变化引起。实验将检查异常的 DA受体的细胞质隔离。 更具体地将DA受体功能障碍与发育 将在D1-I-小鼠和家兔中检查异常变化 在妊娠期用直接D1激动剂治疗。在Aim 2实验中， 研究子宫内可卡因暴露破坏 中间神经元的发育。神经解剖学分析将确定D1是否 通过特定的中间神经元亚群的受体共表达定义了 对妊娠期可卡因最敏感的细胞细胞内染料标记 interneurons将用于分析树突发育的情况下， 多巴胺受体功能障碍在目标3中，将使用两种实验方法 研究产前首次接触可卡因的中枢神经系统如何对 后来可卡因暴露或兴奋性毒性损伤。首先，使用基因微阵列， 我们将确定不同的转录反应， 正常和实验兔的可卡因攻击。第二，兴奋性毒性 从正常和可卡因暴露的动物中分离的神经元的反应性将 在基于细胞的测定中进行研究。跨学科方法将 定义由于产前发育导致的大脑结构和分子适应的改变， 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.