The Potential Role of CRF Neurons in Mediating Onset of Stress-induced Susceptibility via PVT-BNST Connectivity

项目摘要 重度抑郁症（MDD）是最常见的精神疾病，终生患病率为1/5， 目前的治疗方法并不理想。科普持续慢性压力源的能力不足是 MDD的主要易感因素。室旁丘脑（PVT）的神经元在情绪调节中起着关键作用。 唤醒和协调适应性压力相关的神经体液反应。此外，突触靶点 PVT是终纹床核（BNSTov）的卵圆核，调节行为反应 通过释放促肾上腺皮质激素释放因子（CRF）的神经元产生压力。PVT对于调节 对慢性应激的相关神经体液反应，被认为通过PVT-BNSTov的CRF神经元发生 电路.此外，我有初步的电生理和单细胞qRT-PCR数据，在大鼠和组织 在小鼠中，慢性应激伴随着神经元兴奋性的增加， 在BNSTov中选择性地增强crf和crf受体1基因表达。考虑到这些细胞是 在直接PVT突触影响下，这可能代表PVT介导的适应性反应。有趣的是， 与急性应激不同，在慢性应激中，PVT介导的适应性神经反应似乎是暂时的， 独立于压力适应的实际行为表现。因此，该PVT-BNSTov电路 可能是慢性压力转化为抑郁样行为的潜伏期的基础。确定 时间过程中，压力引起的抑郁样行为出现，我采用了慢性社会失败 应激（CSDS）模型，并在各种应激下进行社会互动/蔗糖偏好测试 持续时间为4-10天。我观察到，在CSDS的7到10天之间，动物经历了一次转换， 从社交方式（“弹性”）到社交回避（“敏感”）表型。电生理和 这种快速行为转变背后的分子底物仍然未知。我假设PVT-BNSTov 连接性可能会在面对持续的压力敏感性的时间出现 心理社会应激，通过PVT突触对CRF BNSTov神经元的影响。我打算调查一下 功能PVT-BNSTov电路使用电生理学，单细胞转录组学和先进的光学 电路解剖方法（DREADDs）。首先，我将通过关联束追踪建立功能连接 和c-Fos活性与捕获行为转换的时间段内的共现（aim 1）。那我 将在离体全细胞膜片钳中记录固有的神经元特性，并获得细胞质， 行为转变之前或之后的细胞中的单细胞qRT-PCR分析（目的2）。最后，我将建立 PVT-BNST回路在通过时间和电路特异性介导易感性的时间发作中的必要性 使用DREADD进行操作（目的3）。该提议的最先进的电路和单元类型特定 操作将提供新的洞察应激胰岛素依赖机制的基础MDD病因， 这将为MDD提供更有效的治疗策略。

Project Summary Major Depressive Disorder (MDD) is the most common psychiatric disorder with a lifetime prevalence of 1 in 5, treatment for which is currently suboptimal. Deficits in ability to cope with ongoing chronic stressors are one of the chief predisposing factors to MDD. Neurons of the Paraventricular Thalamus (PVT) are critical in emotional arousal and orchestrate adaptive stress-relevant neurohumoral responses. Furthermore, a synaptic target of the PVT, the oval nucleus of the Bed Nucleus of the Stria Terminals (BNSTov), regulates behavioral responses to stress through Corticotropin-Releasing Factor (CRF)-releasing neurons. The PVT is critical in regulating relevant neurohumoral responses to chronic stress, thought to occur via CRF-neurons of a PVT-BNSTov circuit. Additionally, I have preliminary electrophysiological and single-cell qRT-PCR data in the rat and tissue micropunches in the mouse, that chronic stress accompanies increases in neuronal excitability and enhancement of crf and crf receptor 1 gene expression selectively in the BNSTov. Given that these cells are under direct PVT synaptic influence, this could represent a PVT-mediated adaptive response. Interestingly, unlike in acute stress, in chronic stress, PVT mediated adaptive neural responses appear to be temporally independent of the actual behavioral expression of that stress adaptation. Therefore, this PVT-BNSTov circuit may underlie the latency in the conversion of chronic stress into depressive-like behaviors. To determine the time course wherein stress-induced depressive-like behavior emerges, I employed the Chronic Social Defeat Stress (CSDS) paradigm in mice, and conducted social interaction/sucrose preference testing at various stress duration lengths of 4-10 days. I observed that between 7 and 10 days of CSDS, animals underwent a switch from social approach (“resilient”) to socially avoidant (“susceptible”) phenotypes. The electrophysiological and molecular substrates underlying this rapid behavioral shift remains unknown. I hypothesize that PVT-BNSTov connectivity may govern the temporal emergence of stress susceptibility in the face of persistent psychosocial stress, through PVT synaptic influence on CRF BNSTov neurons. I plan to investigate this functional PVT-BNSTov circuit using electrophysiological, single-cell transcriptomics, and advanced optical circuit dissection methods (DREADDs). First, I will establish functional connectivity by correlating tract tracing and c-Fos activity with the co-occurrence over the time period capturing the behavioral switch (aim 1). Then, I will record in ex-vivo whole-cell patch clamp the intrinsic neuronal properties and procure the cytoplasm for single-cell qRT-PCR analysis in cells before or after the behavioral transition (aim 2). Lastly, I will establish the necessity of the PVT-BNST circuit in mediating the temporal onset of susceptibility via time- and circuit-specific manipulations using DREADDs (aim 3). This proposed state-of-the-art circuit- and cell-type specific manipulations will provide novel insight into stress insult-dependent mechanisms that underlie MDD etiology, which will give rise to more effective therapeutic strategies for MDD.