Cocaine and Brain Development

描述(由申请人提供)：该项目的长期目标是确定母亲滥用可卡因对胎儿大脑发育的影响是否通过多巴胺受体信号机制受损来调节。目前这项提议的具体目标是检查可卡因诱导的多巴胺受体信号转导障碍是否导致小鼠胚胎神经元迁移的缺陷。出生前接触可卡因似乎减少了小鼠胚胎大脑中GABA神经元从神经节隆起到脑壁的迁移。多巴胺受体的激活也会影响这种迁移。孕期接触可卡因会损害多巴胺受体信号。因此，我们假设孕期接触可卡因通过损害多巴胺受体信号机制来干扰GABA神经元从神经节隆起到脑壁的迁移。我们提出了三个具体目标来检验我们的假设。具体目标1将通过定量分析受体mRNA、蛋白、结合位点、激动剂诱导的环磷酸腺苷合成、CREB和DARPP 32的磷酸化来研究可卡因诱导的多巴胺受体信号的变化。具体目标2将确定可卡因暴露所产生的GABA神经元迁移缺陷是否可以通过将多巴胺受体结构电穿孔到神经节隆起的神经元中来恢复。专门的目标3将使用多巴胺受体基因敲除的小鼠和功能丧失和获得相结合的分析来确认这些受体在神经元迁移中的作用。从神经节隆起迁移到脑壁的GABA神经元在整个大脑皮层建立抑制回路。临床研究表明，产前接触可卡因会导致GABA中介功能的持久缺陷，如注意力、语言发展和学习。发育中的大脑多巴胺能系统的失衡也会导致类似的损伤。因此，拟开展的重点实验对GABA神经元迁移、孕期可卡因暴露和多巴胺受体信号转导具有重要的临床意义。孕妇滥用可卡因仍然是一个重大的公共卫生和社会经济问题。然而，可卡因对发育中的大脑的作用的细胞和分子机制还不完全清楚。这项拟议的研究通过研究可卡因、多巴胺和GABA回路发育之间的联系，有望对可卡因对胎儿大脑发育的作用机制提供新的见解。

DESCRIPTION (provided by applicant): The long term goals of the project are to determine if the effects of maternal cocaine abuse on fetal brain development are mediated by impairment of dopamine receptor signaling mechanisms. The specific goal of the current proposal is to examine if cocaine-induced impairment of dopamine receptor signaling contributes to deficits in neuronal migration in mouse embryos. Prenatal cocaine exposure appears to decrease GABA neuron migration from the ganglionic eminence to the cerebral wall in the embryonic mouse brain. Dopamine receptor activation also influences this migration. Prenatal cocaine exposure impairs dopamine receptor signaling. Therefore, we hypothesize that prenatal cocaine exposure interferes with GABA neuron migration from the ganglionic eminence to the cerebral wall by impairing dopamine receptor signaling mechanisms. We propose 3 Specific Aims to test our hypothesis. Specific Aim 1 will examine cocaine-induced changes in dopamine receptor signaling by quantitative analysis of receptor mRNA, protein, binding sites, agonist- induced cyclic AMP synthesis, phosphorylation of CREB and DARPP 32. Specific Aim 2 will determine if the deficits in GABA neuron migration produced by the cocaine exposure can be restored by electroporation of dopamine receptor constructs into neurons of the ganglionic eminence. Specific Aim 3 will use dopamine receptor knockout mice and a combination of loss and gain of function assays to confirm the role of these receptors in neuronal migration. The GABA neurons that migrate from the ganglionic eminence to the cerebral wall establish inhibitory circuits throughout the cerebral cortex. Clinical studies show that prenatal cocaine exposure causes lasting deficits in GABA-mediated functions, such as attention, language development and learning. Imbalance in the dopaminergic system of the developing brain also can cause similar impairments. Therefore, the focus of the proposed experiments on GABA neuron migration, gestational cocaine exposure and dopamine receptor signaling has significant clinical relevance. Cocaine abuse by pregnant women continues to be a major public health and socio-economic concern. Yet cellular and molecular mechanisms of cocaine's action on the developing brain are incompletely understood. The proposed studies promise novel insights into the mechanism of cocaine's action on fetal brain development by examining the link between cocaine, dopamine and development of GABA circuits.