Neuronal and vascular interactions in the CNS

项目摘要/摘要： 人体内没有一个器官比大脑更严重地依赖血液的持续供应。这个 循环系统对大脑的重要性由大脑占2%的事实得到证明 身体总质量，但它接受20%的心输出量。此外，大脑不含局部燃料。 储备，就像外围器官一样。在行为过程中，大脑区域被招募用于特定的任务，并且必须 迅速“上线”。大脑通过一种称为神经血管耦合的过程来调节自己的血液供应， 在这种情况下，神经活动迅速增加局部血流量，以满足局部大脑的时刻变化 能源需求。神经血管偶联障碍导致神经退行性变和血管 痴呆症。神经血管耦合也是脑功能成像的基础，这是目前唯一的方法 来推断人类全脑神经元的激活。尽管了解大脑是如何 调节自身的血液供应，神经血管偶联的分子和细胞机制是 仍然不清楚。在这个提议中，我们开发了一种双光子活体成像范例，它可以 同时测量神经活动(通过基因编码的钙指示器)和血管动力学 (血管直径和血流量)在清醒小鼠的单血管分辨率下，使我们能够捕捉到 神经血管对自然刺激(胡须刺激)的高时间和空间分辨率反应 活着。我们将把这种最先进的活体成像技术与强大的分子、电生理、 用超微结构和遗传学的方法来阐明 神经血管偶联。我们的活体成像和小鼠桶状皮质遗传学的初步数据， 提示脑内皮细胞(ECs)在神经血管偶联中发挥积极作用。传统上，欧洲共同体 被认为是被动地参与神经血管偶联，是一个同质的群体。我们 发现AECs和CECs表现出分子和亚细胞的差异，并在 神经血管偶联。我们提议的工作将确定细胞、亚细胞和分子机制。 血管树不同节段的内皮细胞通过其启动、传递和执行 神经血管偶联。具体地说，我们将演示血管树上不同类型的内皮细胞是如何 调节神经血管偶联，从而连接神经活动和局部血流变化之间的点。 我们希望我们能够在清醒的高空间小鼠身上无创地对中枢小血管进行成像 时间分辨率，以及其他复杂的技术，将使我们能够识别关键的分子 以及体内神经血管偶联的亚细胞机制。此外，我们的结构和 分子发现将为脑血管生物学领域提供可广泛使用的工具。最后， 这些数据将为我们加速了解和治疗与中枢神经系统相关的疾病提供关键信息 小血管和血管性痴呆。

Project Summary/abstract: There is no organ in the body that more heavily depends on a continuous supply of blood than the brain. The importance of the circulatory system to the brain is demonstrated by the fact that the brain makes up 2% of total body mass but it receives 20% of cardiac output. Furthermore, the brain does not contain local fuel reserves, as peripheral organs do. During behavior, brain regions are recruited for specific tasks and must be brought “online” quickly. The brain regulates its own blood supply via a process called neurovascular coupling, in which neural activity rapidly increases local blood flow to meet moment-to-moment changes in regional brain energy demand. Impairments in neurovascular coupling contributes to neurodegeneration and vascular dementia. Neurovascular coupling is also the basis for functional brain imaging, which is currently the only way to infer brain-wide neuronal activation in humans. Despite the importance of understanding how the brain regulates its own blood supply, the molecular and cellular mechanisms underlying neurovascular coupling are still not clear. In this proposal, we have developed a two-photon in vivo imaging paradigm that can simultaneously measure neural activity (via a genetically encoded calcium indicator) and vascular dynamics (vessel diameter and blood flow) at single-vessel resolution in awake mice, enabling us to capture the neurovascular response to a natural stimulus (whisker stimulation) at high temporal and spatial resolution in vivo. We will combine this state-of-art in vivo imaging techniques with powerful molecular, electrophysiological, ultrastructural, and genetic approaches to elucidate the fundamental cellular mechanisms governing neurovascular coupling. Our preliminary data with in vivo live imaging and mouse genetics in the barrel cortex, suggest that endothelial cells (ECs) in the brain play active roles in neurovascular coupling. Traditionally, ECs were considered to be passively involved in neurovascular coupling, and to be a homogenous population. We found aECs and cECs display molecular and subcellular differences, and play distinct roles during neurovascular coupling. Our proposed work will identify the cellular, subcellular, and molecular mechanisms by which endothelial cells from different segments of the vascular tree initiate, transmit, and implement neurovascular coupling. Specifically, we will demonstrate how different type of ECs along the vascular tree mediate neurovascular coupling, thus connecting the dots between neural activity and local blood flow change. We expect that our ability to image CNS small blood vessels non-invasively in awake mice with high spatial and temporal resolution, along with other sophisticated techniques, will allow us to identify critical molecular and subcellular mechanisms that underlie neurovascular coupling in vivo. Moreover, our structural and molecular findings will provide tools that can be broadly used by the field to cerebrovascular biology. Finally, the data will provide critical information to accelerate our understanding and treatment of CNS diseases related to small vessels and vascular dementia.