The neuronal basis of cannabis-induced developmental deficits in the CNS

描述（由申请人提供）：内源性大麻素系统最近被确立为一个主要的反馈回路，控制着成人中皮质边缘系统中多个神经化学上不同的突触群体的突触可塑性。然而，内源性大麻素信号在中枢神经系统模式中的功能，特别是指导神经元前体的迁移和表型形态分化，在胚胎脑中的功能尚不清楚。考虑到大麻素受体是大麻中的活性成分9-四氢大麻酚（THC）的首选细胞靶点，怀孕期间吸食大麻会导致受影响后代终生的运动和认知缺陷，并由中皮质边缘神经元回路集中控制，我们对大脑发育过程中内源性大麻素信号传导的细胞特征缺乏了解是令人惊讶的。我们已经发现，早在妊娠14周，CB1大麻素受体就选择性地定位于人类胚胎的边缘系统，内源性大麻素和植物大麻素对神经元迁移和皮层中间神经元的规范具有指导作用，并确定内源性大麻素是一类新的排斥轴突引导gaba能中间神经元的线索。在本项目中，我们将重点关注：(1)确定四氢大麻酚暴露在神经元前体迁移和神经元突触发生的关键时期的细胞后果，特别强调它们与中皮质边缘系统中GABAergic和多巴胺能（DAergic）神经元的关联；(2)在转录组水平上确定与四氢大麻酚诱导的发育变化相关的细胞调节机制。一个综合的，多学科的系列研究将在绿色荧光蛋白表达报告小鼠中进行，这些小鼠可以选择性地可视化遗传标记的目标神经元。随后，将结合产前四氢大麻酚给药动物模型研究的转录组分析，鉴定中皮质边缘神经元中发育调节的基因集，这些基因集的表达在大麻暴露的人类胎儿大脑标本的独特材料中受到产前四氢大麻酚的差异调节。扩大我们对内源性大麻素系统控制的基本发育和信号传导原理的了解，将为产前大麻暴露的病理机制提供重要的见解，考虑到孕妇持续频繁使用大麻，这是社会关注的重要问题。该项目的结果将扩大我们目前对内源性大麻素信号系统在大脑发育过程中的功能意义以及与产前大麻暴露相关的病理机制的理解。考虑到大麻是孕妇和育龄年轻女性最常用的非法药物，这些见解具有重要意义。

DESCRIPTION (provided by applicant): The endocannabinoid system has recently been established as a major feedback circuitry controlling synaptic plasticity at multiple neurochemically distinct synapse populations in the meosocorticolimbic system of the adult. However, the functions of endocannabinoid signaling during patterning of the central nervous system, in particular instructing the migration and phenotypic morphometric differentiation of neuronal precursors, in the embryonic brain are unknown. Our lack of knowledge on the cellular specification of endocannabinoid signaling during brain development is surprising given that cannabinoid receptors are the preferred cellular targets of 9-tetrahydrocannabinol (THC), the active component from cannabis, and cannabis smoking during pregnancy causes life-long motor and cognitive deficits, controlled centrally by mesocorticolimbic neuronal circuitries, in the affected offspring. We have previously found that CB1 cannabinoid receptors are selectively localized to the limbic system of the human embryo as early as week 14 of gestation, endocannabinoids and phytocannabinoids are instructive for neuronal migration and cortical interneuron specification, and identified endocannabinoids as a novel class of repulsive axon guidance cues for GABAergic interneurons. In the present project we will focus on: (1) defining the cellular consequences of THC exposure during critical periods of neuronal precursor migration and neuronal synaptogenesis with particular emphasis on their association with GABAergic and dopaminergic (DAergic) neurons in the mesocorticolimbic system and (2) identifying cellular regulatory mechanisms on the transcriptome level that are relevant to THC-induced developmental changes. An integrative, multidiscplinary series of studies will be performed in green fluorescent protein-expressing reporter mice that allow selective visualization of genetically-tagged target neurons. Subsequently, transcriptome analysis from animal model studies of prenatal THC administration will be combined with identifying developmentally-regulated gene sets in mesocorticolimbic neurons whose expression is differentially regulated by prenatal THC in a unique material of cannabis-exposed human fetal brain specimens. Expanding our knowledge of the basic developmental and signaling principles controlled by the endocannabinoid system will provide significant insights about pathological mechanisms of prenatal cannabis exposure that is of significant concern in society considering the continued frequent use of marijuana by pregnant women. The results of this project will expand our current understanding of the functional significance of the endogenous cannabinoid signaling system during brain development and the pathological mechanisms associated with prenatal cannabis exposure. Such insights are of significant importance considering that marijuana is the most commonly used illicit drug by pregnant women and young women of childbearing age.