Amygdala hyper-connectivity in a mouse model of unpredictable early life stress

摘要 儿童期虐待增加了剂量依赖患者焦虑和其他精神病理的风险 举止。生命早期多种不良事件协同作用影响焦虑的机制还不是很清楚。 在人类中被理解，在早期生活应激的动物模型中很少努力澄清这个问题 (ELS)。我们最近表明，暴露在UPS中，这是一种复杂且不可预测的ELS小鼠模型， 导致焦虑的强劲增加，这在暴露于简单且可预测的 ELS称为有限卧具(LB)。有趣的是，暴露在路易斯安那或UPS中并没有影响焦虑 雌性小鼠的行为。由于杏仁核与额叶-边缘脑区域的连接，如 海马区(HPC)和前额叶皮质(PFC)在焦虑样行为和 童年时期遭受虐待会导致我们使用的这些大脑区域之间的异常连接 静息状态功能磁共振成像(RsfMRI)比较UPS和对照组杏仁核与HPC和PFC的连接性 雄鼠。我们发现杏仁核和前额叶之间以及杏仁核之间的连接增强。 以及UPS男性中的HPC。重要的是，这些联系的强度与焦虑高度相关- 就像行为一样。在本应用中，我们假设杏仁核与PFC和HPC连接 在围产期接受小胶质细胞介导的修剪。在男性中，更严重的ELS形式，如 UPS，导致出生后小胶质细胞中主调控因子PU.1的表达更大程度地降低。此入站 TURN在调节焦虑的额叶-边缘连接的精细化过程中会导致剂量依赖性的损害。 暴露于LB或UPS对女性的PU1水平和小胶质细胞功能没有影响。因此，女性 当暴露在LB或UPS中时，表现出正常的杏仁核连接和焦虑。在AIM 1中工作将使用rsfMRI 和高分辨率DTI，以测试不同类型的ELs(UPS和LB)如何与性别相互作用改变额缘 连通性。在目标2中，我们将使用光遗传学和化学遗传学病毒来标记和操纵基底外侧 杏仁核(BLA)投射到PFC和HPC。这种方法将使我们能够精确地映射 这些投射，确定它们对焦虑的贡献，并评估它们诱导c-fos激活和 使用功能磁共振成像改变粗体信号。AIM 3中提出的研究将使用rsfMRI和高分辨率DTI来 研究PU.1-HETS小鼠的功能和结构连通性。这种方法的优势在于 我们团队的不同专业知识。这一多学科的努力使我们能够利用小胶质细胞特异的基因 操作，使用光遗传和化学遗传工具严格测试因果关系，并利用人类成像 评估ELS小鼠模型中大脑连通性的工具。

Abstract Childhood maltreatment increases the risk for anxiety and other psychopathologies in a dose-dependent manner. The mechanisms by which multiple adverse events early in life synergize to affect anxiety is poorly understood in humans and little effort has been made to clarify this issue in animal models of early life stress (ELS). We recently showed that exposure to UPS, which is a complex and unpredictable mouse model of ELS, leads to robust increase in anxiety that was not seen in mice exposed to a simple and predictable paradigm of ELS known as the limited bedding (LB). Interestingly, exposure to LB or UPS did not affect anxiety-like behavior in female mice. Since amygdala connectivity with fronto-limbic brain regions such as the hippocampus (HPC) and the prefrontal cortex (PFC) play an important role in anxiety-like behavior and exposure to childhood maltreatment leads to abnormal connectivity between these brain regions we used resting state fMRI (rsfMRI) to compare amygdala connectivity with the HPC and the PFC in UPS and control male mice. We found increased connectivity between the amygdala and the PFC and between the amygdala and the HPC in UPS males. Importantly, the strength of theses connections was highly correlated with anxiety- like behavior. In this application we hypothesize that amygdala connectivity with the PFC and the HPC undergo microglial-mediated pruning during the perinatal period. In males, more severe forms of ELS, such as UPS, lead to greater reduction in the expression of the master regulator PU.1 in postnatal microglia. This in turn causes a dose-dependent impairment in the refinement of fronto-limbic connections that regulate anxiety. Exposure to LB or UPS has no effect on PU.1 levels and microglial function in females. As a result, females show normal amygdala connectivity and anxiety when exposed to LB or UPS. Work in aim 1 will use rsfMRI and high resolution DTI to test how different types of ELS (UPS and LB) interact with sex to alter fronto-limbic connectivity. In aim 2 we will use optogenetics and chemogenetics viruses to label and manipulate basolateral amygdala (BLA) projections to the PFC and HPC. This approach will allow us to precisely map the size of these projections, determine their contribution to anxiety, and assess their ability to induce c-fos activation and to alter BOLD signal using fMRI. Studies proposed in aim 3 will use rsfMRI and high resolution DTI to characterize functional and structural connectivity in PU.1-hets mice. The strength of this approach lies in the diverse expertise of our team. This multidisciplinary effort allows us to use microglial specific genetic manipulations, rigorously test causality using optogenetic and chemogenetic tools, and utilize human imaging tools to assess brain connectivity in a mouse model of ELS.