How microglia sense and regulate neuronal activity in the adult brain

项目摘要/摘要 小胶质细胞是中枢神经系统的先天免疫细胞，与成人大脑中的神经元相互作用。 小胶质细胞受体和通路具有改变复杂网络功能的能力。这一过程 从小胶质细胞感知特定的神经元信号开始。然而，使用的下游机制 小胶质细胞执行特定的反应/结果还不是很清楚。这项研究的目的是 了解小胶质细胞如何在过度活动(例如，癫痫发作)和活动不足(例如， 麻醉)，然后可能触发独特的功能反应，改变成人大脑中的神经元电路。ATP 多动时的嘌呤信号是小胶质细胞与癫痫发作中的神经元相互作用的一个有充分证据的信号， 减轻癫痫发作的严重程度。然而，细胞内小胶质细胞(第二信使，如 CA2信号)对ATP的响应还只有部分了解。独特的细胞内信号级联在 小胶质细胞可能对它们的功能反应产生不同的影响。这些通路将使用急性 脑切片和活体双光子成像以及一套新的遗传和基于病毒的工具来揭示 特别是小胶质细胞的钙通路是如何影响癫痫反应的。在运动不足的时候， 去甲肾上腺素信号允许小胶质细胞在麻醉下更好地与神经元相互作用。这些活动的目的是 网络功能的相互作用尚不清楚，但将使用小胶质细胞的活体双光子成像进行解剖。 完整大脑中的神经元动力学，加上高细节的3D电子显微镜重建 结构相互作用。以前使用化学遗传学和条件基因敲除方法改变的经验 小胶质细胞的功能也被用来剖析调节低活性神经回路反应的特定通路。 最终，确定小胶质细胞如何调节神经元功能，包括潜在的机制和它们的 对电路的影响，对于充分理解小胶质细胞是如何整合到复杂的神经元电路中是至关重要的。 因为在癫痫和睡眠障碍等脑部疾病中，它们变得不受控制。

PROJECT SUMMARY/ABSTRACT Microglia are innate immune cells of the central nervous system, which interact with neurons in the adult brain. Microglial receptors and pathways have a demonstrated ability to alter complex network function. This process begins with microglia sensing specific neuronal signals. However, the downstream mechanisms used by microglia to enact specific responses/outcomes is not well understood. The purpose of this research is to understand how microglia sense neuronal activity during hyperactivity (e.g., seizures) and hypoactivity (e.g., anesthesia), which may then trigger unique functional responses to alter neuronal circuits in the adult brain. ATP purine signaling during hyperactivity is a well-documented signal for microglia to interact with neurons in seizure, reducing seizure severity. However, the complexity of microglial intracellular (secondary messenger such as Ca2+ signaling) responses to ATP is only partially understood. Unique intracellular signaling cascades in microglia may differentially influence their functional responses. These pathways will be interrogated using acute brain slice and in vivo two-photon imaging along with a suite of new genetic and virus-based tools to uncover how the calcium pathway of microglia in particular informs seizure responses. During hypoactivity, a loss of norepinephrine signaling allows microglia to better interact with neurons under anesthesia. The purpose of these interactions for network function is unknown, but will be dissected using in vivo two-photon imaging of microglia- neuron dynamics in the intact brain, coupled with 3D-electron microscope reconstruction of highly detailed structural interactions. Previous experience using chemogenetic and conditional knockout approaches to alter microglia function are also utilized to dissect specific pathways regulating hypoactive neural circuit responses. Ultimately, determining how microglia regulate neuronal function, including underlying mechanisms and their impact on circuitry, is essential to fully understand how microglia are integrated into the complex neuronal circuits as they become dysregulated in brain diseases, such as seizures and sleep disorders.