Endocannabinoids regulate microglia in developing brain

内源性大麻素调节大脑发育中的小胶质细胞

• 批准号: 10386019
• 负责人: MARGARET M. MCCARTHY
• 金额: $ 49.57万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2027-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10386019
• 关键词: 2-arachidonylglycerol; Adolescence; Adolescent; Adult; Age; Amygdaloid structure; Androgen Receptor; Androgens; Astrocytes; Behavior; Birth; Brain; Brain region; Breast Feeding; CNR1 gene; CNR2 gene; Cell Survival; Cells; Chemotactic Factors; Complement; Complement 3b; Complex; Consumption; Dependovirus; Development; Endocannabinoids; Enzymes; Epigenetic Process; Exposure to; Face; Family member; Female; Foundations; Future; Gene Targeting; Genes; Goals; Human; Immune; Immune system; In Situ Hybridization; Innate Immune System; Internet; Knowledge; Left; Legal; Life; Marijuana; Measures; Medial; Mediating; Medical; Membrane Lipids; Messenger RNA; Microglia; Natural Immunity; Neonatal; Neuroimmune system; Neurons; Newborn Infant; Organ; Participant; Perception; Phagocytes; Phagocytosis; Phenotype; Play; Population; Pregnancy; Process; Production; Proliferating; Proteins; RNA; Rattus; Research; Safety; Sex Differences; Signal Transduction; Signaling Molecule; Small Interfering RNA; Small Nuclear RNA; Social Behavior; Source; Specificity; Stimulus; Surface; System; THC exposure; Techniques; Time; Vacuum; androgen sensitive; astrocyte progenitor; axon guidance; brain cell; cell type; complement system; critical period; density; endogenous cannabinoid system; excitatory neuron; fetal; inhibitory neuron; male; marijuana use in pregnancy; neural circuit; neurogenesis; perinatal brain; programs; response; sex; social; tool; transcriptome; transcriptomics

Endocannabinoids (EDCs) and the innate immune system are two early signaling systems which independently and together profoundly influence brain development. Critical windows of development are also often sensitive periods for disruption by exogenous stimuli. We have discovered a unique critical period in the neonatal amygdala of the rat during which the innate immune cells of the brain, microglia, actively engulf and kill newborn cells that if left unmolested would have gone on to become astrocytes. Through this mechanism the future density of astrocytes in the amygdala is determined. Most remarkably, the optimal density is lower for males than females in that it is causally responsible for increased neuronal activity many weeks later during epochs of adolescent social play. Equally remarkable, the increased phagocytic activity of microglia in the male amygdala is a direct consequence of a higher EDC tone, which is in turn developmentally programmed by elevated androgens in neonatal males. Changes to either androgen levels or, more importantly, EDC tone, including by exposure to THC, during the critical period permanently alters the neuronal/astrocytic population and playfulness during adolescence. Marijuana use during pregnancy and breastfeeding is prevalent and increasing due to legalization, decriminalization and medicalization but we are largely ignorant of the potential consequences to the fetal and newborn brain. Advances in transcriptomics and adeno-associated virus (AAV) techniques provide new tools for exploration and precision not previously accessible for the rat. A primary goal is a deep mechanistic understanding of endocannabinoid-induced microglia phagocytosis of astrocytic progenitors to illuminate with unprecedented specificity the interaction between immune, neuronal, astrocytic and progenitor cells. An additional goal is to establish a larger framework for understanding development THC exposure that converges on inhibitory neurons in brain regions regulating sex-typic social behaviors. We will achieve these dual ends via the following Specific Aims. Aim 1 will fully characterize the endocannabinoid and innate immune systems of the developing amygdala by high precision cell phenotyping, identification of the source of complement proteins needed for phagocytosis, and transcriptomics to identify genes mediating cell survival. In Aim 2 we will selectively reduce androgen receptor in one cell type at a time to determine the source of the sex difference in endocannabinoid tone and Aim 3 will interrogate the relationship between the effects of THC, EDCs and androgen action with an emphasis on inhibitory neurons across brain regions. Combined, these studies will provide unprecedented clarity in the cellular participants and mechanisms establishing a sex difference in a social circuit and how that process can go awry as a consequence of developmental THC exposure.

内源性大麻素（EDC）和先天免疫系统是两个早期信号系统，它们独立和共同地深刻影响大脑发育。发育的关键窗口也常常是受到外源刺激干扰的敏感时期。我们在大鼠的新生杏仁核中发现了一个独特的关键时期，在此期间，大脑的先天免疫细胞小胶质细胞积极吞噬并杀死新生细胞，如果不受到干扰，这些新生细胞将继续成为星形胶质细胞。通过这种机制，杏仁核中星形胶质细胞的未来密度被确定。最值得注意的是，男性的最佳密度低于女性，因为它是几周后青少年社交游戏时期神经元活动增加的原因。同样值得注意的是，男性杏仁核中小胶质细胞吞噬活性的增加是 EDC 张力升高的直接结果，而 EDC 张力又是由新生男性中雄激素升高而进行的发育编程。在关键时期，雄激素水平的变化，或更重要的是 EDC 基调的变化，包括接触 THC，会永久改变青春期的神经元/星形胶质细胞数量和玩耍性。由于合法化、非刑事化和医疗化，怀孕和母乳喂养期间吸食大麻非常普遍，而且还在不断增加，但我们基本上不知道大麻对胎儿和新生儿大脑的潜在影响。转录组学和腺相关病毒 (AAV) 技术的进步为大鼠提供了以前无法获得的探索和精确度的新工具。主要目标是深入了解内源性大麻素诱导的小胶质细胞对星形胶质细胞祖细胞的吞噬作用，以前所未有的特异性阐明免疫、神经元、星形胶质细胞和祖细胞之间的相互作用。另一个目标是建立一个更大的框架来理解发育过程中的 THC 暴露，该框架集中于调节性别型社会行为的大脑区域的抑制性神经元。我们将通过以下具体目标实现这些双重目标。目标 1 将通过高精度细胞表型分析、吞噬作用所需补体蛋白来源的鉴定以及转录组学来鉴定介导细胞存活的基因，全面表征发育中杏仁核的内源性大麻素和先天免疫系统。在目标 2 中，我们将一次选择性地减少一种细胞类型中的雄激素受体，以确定内源性大麻素音调中性别差异的来源，目标 3 将探讨 THC、EDC 和雄激素作用的影响之间的关系，重点是抑制性神经元跨越大脑区域。结合起来，这些研究将为细胞参与者和社会回路中建立性别差异的机制提供前所未有的清晰度，以及该过程如何因发育性 THC 暴露而出错。