Role of VTA-Amygdala Neural Circuit in Mediating Anxiety-Related Behaviors

项目总结 焦虑症是最常见的精神疾病，困扰着全球2.73亿人。这个 焦虑症的症状非常复杂，其原因也鲜为人知。此外，一个 相当数量的焦虑症患者也出现了抑郁样症状， 这使得对潜在机制的调查变得复杂。在这个项目中，我们建议采取 重复社会失败压力(RSD)模型的优势，该模型可导致焦虑(A)或混合型 不同亚组小鼠的焦虑/抑郁(A/D)表型，试图剖析 调节焦虑行为的神经生理底物。使用这个模型，我们意外地发现 特定的神经回路病理活动与焦虑行为完全相关。简而言之，虽然RSD 在所有暴露的受试者中诱导严重的焦虑行为，小鼠的子集根据它们的 抑郁表型：严重的快感缺乏和回避表现的小鼠(易感)不是小鼠 表现出这些抑郁症状(有弹性)。因此，在这个项目中，我们将他们标记为焦虑(A)和 焦虑/抑郁(A/D)亚组。大量研究表明腹侧被盖区的作用 焦虑症和抑郁症中的(VTA)多巴胺(DA)亚回路。我们之前观察到，不适应的射击 活动发生在投射到内侧前额叶皮质的VTA DA神经元和VTA DA A/D小鼠(抑郁易感小鼠)向伏核(NAC)投射的神经元，但在A/D小鼠不投射到NAC 小鼠(抑郁恢复组)。我们进一步证明了射击不适应之间的因果联系 这些回路和抑郁相关的行为。令人惊讶的是，在我们R21的支持下，使用体外 电生理学研究表明，投射到杏仁核的VTA神经元的放电活动。 AMG)在A/D和A小鼠中都显著降低，这种VTA-AMG回路活动与 焦虑表型的表达，但不是与抑郁相关的表型。根据这些初步调查结果， 我们的中心假设是VTA-AMG回路在焦虑样行为中起着关键作用 在RSD后的A/D和A小鼠中均可观察到。为了测试这一点，我们提出了三个具体目标：(I) A/D和A组VTA-AMG DA环神经元的病理细胞和分子变化 通过使用体内光电极记录和体外脑片记录；(Ii)确定 RSD在焦虑出现和表达过程中如何改变VTA-AMG DA神经元的活动 体内钙纤维光度法记录，最后(III)确定VTA-AMG DA的功能作用 男性RSD诱发焦虑行为的神经元光遗传调控 和雌性老鼠。通过利用这些细胞类型和电路特定的电生理、活体钙成像 和光遗传技术，我们将确定神经元活动之间是否存在因果关系 VTA-AMG DA环路与焦虑相关行为。

PROJECT SUMMARY Anxiety disorders are the most common psychiatric illness, afflicting 273 million people worldwide. The symptoms of anxiety disorders are highly complex and the causes are poorly understood. Additionally, a substantial number of patients suffering from anxiety disorders also present with depressive-like symptoms, which complicates the investigation of the underlying mechanisms. In this project, we propose to take advantage of the repeated social defeat stress (RSDS) model that induces anxiety (A) or mixed anxiety/depression (A/D) phenotypes in separate subgroups of mice, in an effort to dissect the neurophysiological substrate regulating anxiety behaviors. Using this model, we unexpectedly identified that specific neural circuit pathological activity is exclusively correlated with anxiety behaviors. Briefly, while RSDS induces severe anxiety behaviors in all subjects exposed, a subset of mice is segregated based on their depressive phenotypes: profound anhedonia and avoidance-displaying mice (susceptible) from mice not displaying these depressive symptoms (resilient). Thus, in this project, we label them as anxiety (A) and anxiety/depression (A/D) subgroups. Numerous studies have implicated the role of ventral tegmental area (VTA) dopamine (DA) subcircuits in anxiety and depression. We previously observed that maladaptive firing activity occurred in the VTA DA neurons projecting to the medial prefrontal cortex (mPFC) and VTA DA neurons projecting to the nucleus accumbens (NAc) in A/D mice (depression-susceptible mice), but not in A mice (depression-resilient group). We further demonstrated the causal link between the firing maladaptations in those circuits and depression-related behaviors. Surprisingly, with the support of our R21, using ex vivo electrophysiological studies we show that the firing activity of VTA neurons projecting to the amygdala (VTA- AMG) is dramatically decreased in both A/D and A mice, and this VTA-AMG circuit activity correlates with the expression of anxiety phenotype but not depressive-related phenotypes. Based on these preliminary findings, our central hypothesis is that the VTA-AMG circuit plays a crucial role in the anxiety-like behaviors observed in both A/D and A mice following RSDS. To test this, we propose three Specific Aims: (I) to investigate the pathological cellular and molecular alterations of VTA-AMG DA circuit neurons in A/D and A male and female mice by use of in vivo optrode recordings and ex vivo brain slice recordings; (II) To define how RSDS alters the activity of VTA-AMG DA neurons during the emergence and expression of anxiety using in vivo calcium fiber photometry recordings, and finally (III) to determine the functional role of VTA-AMG DA neurons in mediating RSDS-induced anxiety behaviors by optogenetically manipulating these circuits in male and female mice. By utilizing these cell type- and circuit-specific electrophysiological, in vivo calcium imaging and optogenetic techniques, we will determine if a causal relationship exists between the neuronal activity of VTA-AMG DA circuit and anxiety-related behaviors.