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

描述(申请人提供)：内源性大麻素系统最近被确定为控制成人皮质边缘系统中多个神经化学不同突触群体的突触可塑性的主要反馈回路。然而，内源性大麻素信号在中枢神经系统模式形成过程中的功能，特别是在胚胎脑中指导神经元前体的迁移和表型形态分化的功能尚不清楚。我们对大脑发育过程中内源性大麻素信号的细胞特性缺乏了解是令人惊讶的，因为大麻素受体是大麻的活性成分9-四氢大麻酚(THC)的首选细胞靶标，而怀孕期间吸食大麻会导致受影响后代终身的运动和认知障碍，这些障碍由中皮质边缘神经元回路集中控制。我们已经发现早在妊娠14周，CB1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的迁移和皮质间神经元的指定具有指导作用，并发现内源性大麻素是GABA能中间神经元的一类新的排斥性轴突引导信号。在本项目中，我们将集中于：(1)确定在神经元前体迁移和神经元突触发生的关键时期暴露的细胞后果，特别是它们与中皮质边缘系统中GABA能和多巴胺能神经元的关系；(2)在转录组水平上识别与THC诱导的发育变化相关的细胞调控机制。将在绿色荧光蛋白表达的报告小鼠中进行一系列综合的、多学科的研究，以选择性地显示带有基因标记的目标神经元。随后，来自产前给予THC的动物模型研究的转录组分析将与在一种独特的暴露于大麻的人胎脑标本中鉴定发育调节的基因集相结合，这些基因集的表达受产前THC的差异调控。扩大我们对由内源性大麻素系统控制的基本发育和信号传递原理的了解，将对产前大麻暴露的病理机制提供重要的见解，考虑到孕妇继续频繁使用大麻，产前大麻暴露是社会非常关注的问题。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青年妇女最常用的非法药物，这种见解具有重要意义。

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.