Project 2: Periarterial CSF pumping: Dependence on state of brain activity

项目 2：动脉周围脑脊液泵送：取决于大脑活动状态

• 批准号: 10673161
• 负责人: Maiken Nedergaard
• 金额: $ 45.58万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2027-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10673161
• 关键词: Affinity; Albumins; Animals; Arousal; Astrocytes; Automobile Driving; Binding; Biological Assay; Blood; Blood Vessels; Blood Volume; Blood flow; Brain; Cells; Compensation; Cranial Nerves; Cyclic AMP; Dependence; Diameter; Dimensions; Electroencephalography; G-Protein-Coupled Receptors; Genetic; Glial Fibrillary Acidic Protein; Global Change; Human; Hyperemia; Image; Individual; Injections; Ketamine; Kidney; Kinetics; Link; Liquid substance; Literature; Lymphatic; Maps; Measurement; Measures; Mechanics; Microspheres; Modeling; Monitor; Mus; Neural Interconnection; Neurons; Optics; Penetration; Play; Population; Population Control; Process; Property; Pump; Pupil; Regulation; Resolution; Role; Route; Scanning; Sedation procedure; Sensory; Signal Transduction; Sleep; Smooth Muscle Myocytes; Source; Testing; Tracer; Vascular Smooth Muscle; Venous; Vibrissae; Work; Xylazine; arteriole; awake; fluid flow; glymphatic clearance; glymphatic flow; glymphatic system; neural; neural circuit; neural patterning; neuroimaging; neurovascular coupling; neurovascular unit; non rapid eye movement; novel; optogenetics; particle; pharmacologic; physical property; response; solute; spatiotemporal; two-photon; wasting

Abstract_Project 2 Many lines of work show that glymphatic flow plays a key role in brain waste clearance during sleep. Yet, the mechanisms driving glymphatic flow and its regulation by the state of brain activity are poorly understood. Like the other projects in the U19 application, Project 2 will focus on understanding what drives periarterial CSF influx. We are basing the periarterial CSF pumping model on the well-documented mechanism of functional hyperemia, i.e., transient increases in blood flow and volume in response to neural activity. We postulate that CSF in parallel is pumped along the periarterial spaces to compensate for local or global changes in vascular volume. Thus, glymphatic fluid transport peaks during NREM sleep because coordinated neural activity drives larger changes in blood volume than in the awake state. Aim 1 will with high spatio-temporal resolution image the effect of whisker stimulation on Ca2+/cAMP signaling in the individual cell populations of the neurovascular unit on the diameters of penetrating arterioles, and on the velocity of CSF in periarterial spaces (as measured by particle tracking). We will determine the drivers of periarterial CSF pumping using optogenetic stimulation of neurons, astrocytes, or smooth muscle cells with simultaneous observations via 2-photon or macroscopic imaging in mice. Aim 2 will test the hypothesis that natural sleep states determine not only the activity pattern of neural circuits, but also the physical dimensions and the functional properties of the perivascular spaces, and thereby the efficacy of periarterial CSF pumping. Operationally, we will use the same paradigms proposed in Aim 1, including sensory whisker stimulations and cell-specific optogenetic activation, in awake and sleeping (NREM) mice. Aim 3 will establish whether periarterial CSF pumping predicts glymphatic clearance. We will take advantage of a novel clearance assay based on intracortical injection of a small fluorescent tracer (DB53, BBB-impermeable) that accumulates in blood after clearance from brain, so that the signal in blood reflects total DB53 brain efflux, independent of the clearance routes. We will systematically manipulate periarterial CSF pumping and determine its effect on DB53 clearance after intracortical delivery. Overall, Project 2 will contribute to the U19 proposal by testing the hypothesis that neural circuit activity determines glymphatic solute clearance by controlling the structural and physical properties of the neurovascular unit and thereby the efficacy of periarterial CSF pumping in a brain state dependent mechanism. Project 2 depends critically on the fluid dynamic modelling in Project 1, while Project 3 will provide key information on which neuronal populations control neurovascular coupling during sleep. Projects 2 and 3 will together serve as an important source of cellular information for the neuroimaging studies in Project 4, bridging cellular mechanisms and consequences for solute clearance with the multiscale dynamics observed in the human brain.

摘要_项目 2 许多研究表明，类淋巴液流动在睡眠期间大脑废物清除中发挥着关键作用。然而， 驱动类淋巴液流动的机制及其受大脑活动状态的调节尚不清楚。喜欢 与 U19 应用程序中的其他项目相比，项目 2 将重点了解驱动动脉周围脑脊液流入的因素。 我们将动脉周围脑脊液泵血模型建立在有据可查的功能性充血机制的基础上， 即，响应神经活动的血流量和容量的短暂增加。我们假设 CSF 并行 沿着动脉周围空间泵送以补偿血管容量的局部或整体变化。因此， 类淋巴液运输在 NREM 睡眠期间达到峰值，因为协调的神经活动会导致更大的变化 血容量高于清醒状态。目标1将以高时空分辨率成像的效果 晶须刺激对神经血管单元单个细胞群中 Ca2+/cAMP 信号传导的影响 穿通小动脉的直径，以及动脉周围空间中脑脊液的速度（通过粒子测量） 追踪）。我们将利用神经元的光遗传学刺激来确定动脉周围脑脊液泵送的驱动因素， 通过小鼠体内的 2 光子或宏观成像同时观察星形胶质细胞或平滑肌细胞。 目标 2 将检验以下假设：自然睡眠状态不仅决定神经回路的活动模式， 还包括血管周围空间的物理尺寸和功能特性，从而 动脉周围脑脊液泵送的功效。在操作上，我们将使用目标 1 中提出的相同范例，包括 在清醒和睡眠（NREM）小鼠中进行感觉胡须刺激和细胞特异性光遗传学激活。目的 图3将确定动脉周围脑脊液泵送是否预测类淋巴清除。我们将利用 基于皮质内注射小型荧光示踪剂（DB53，BBB 不可渗透）的新型清除测定法 从大脑清除后积聚在血液中，因此血液中的信号反映了总的 DB53 脑流出量， 与清关路线无关。我们将系统地操纵动脉周围脑脊液泵送并确定 其对皮质内分娩后 DB53 清除的影响。 总体而言，项目 2 将通过测试神经回路活动的假设来为 U19 提案做出贡献 通过控制神经血管的结构和物理特性来确定类淋巴溶质清除率 单位，从而影响大脑状态依赖机制中动脉周围脑脊液泵送的功效。项目2 关键取决于项目 1 中的流体动力学建模，而项目 3 将提供以下方面的关键信息： 哪些神经元群控制睡眠期间的神经血管耦合。项目2和3将共同作为 项目 4 中神经影像学研究的重要细胞信息来源，桥接细胞 在人脑中观察到的多尺度动力学中溶质清除的机制和后果。