Super-resolution shadow imaging reveals local remodeling of astrocytic microstructures and brain extracellular space after osmotic challenge
Super-resolution shadow imaging reveals local remodeling of astrocytic microstructures and brain extracellular space after osmotic challenge
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超分辨率阴影成像显示渗透后星形细胞微结构和脑细胞外空间的局部重塑
DOI：
10.1002/glia.23995
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发表时间：
2021-03-12
期刊：
影响因子：
6.2
通讯作者：
Nagerl, U. Valentin
中科院分区：
文献类型：
--
作者：
Arizono, Misa;Inavalli, V. V. G. Krishna;Nagerl, U. Valentin
细胞外空间 (ECS) 在大脑生理学中发挥着核心作用，它决定着神经化学物质、离子和营养物质的时间进程和扩散，从而确保适当的大脑稳态和神经元通讯。星形胶质细胞是大脑中最丰富的神经胶质细胞类型，其突起密集地浸润大脑实质。由于星形胶质细胞对渗透压的变化高度敏感，因此它们能够对 ECS 产生强大的生理影响。然而，人们对星形胶质细胞周围 ECS 的空间分布和时间动态知之甚少，这主要是由于缺乏适当的技术来可视化活体脑组织中的 ECS。为了缓解这一技术限制，我们将最近的超分辨率阴影成像技术 (SUSHI) 应用于星形胶质细胞标记的器官型海马脑切片，这使我们能够在现场实验环境中以前所未有的空间分辨率同时对星形胶质细胞和 ECS 的复杂形态进行成像。着眼于海绵状域中的环状星形细胞微观结构，我们发现它们包围着相当大的间质液池和树突棘等细胞结构。在实验渗透挑战后，这些微观结构以池的损失为代价进行重塑和膨胀，有效地增加了星形胶质细胞和细胞结构之间的物理界面。我们的研究揭示了活体脑组织中星形胶质细胞、神经纤维网和 ECS 之间动态微观解剖学关系的新方面，这可能与各种（病理）生理环境中的神经元-胶质细胞通讯具有功能相关性，例如已知会发生渗透紊乱的 LTP 诱导、癫痫发作或急性缺血性中风。
The extracellular space (ECS) plays a central role in brain physiology, shaping the time course and spread of neurochemicals, ions, and nutrients that ensure proper brain homeostasis and neuronal communication. Astrocytes are the most abundant type of glia cell in the brain, whose processes densely infiltrate the brain's parenchyma. As astrocytes are highly sensitive to changes in osmotic pressure, they are capable of exerting a potent physiological influence on the ECS. However, little is known about the spatial distribution and temporal dynamics of the ECS that surrounds astrocytes, owing mostly to a lack of appropriate techniques to visualize the ECS in live brain tissue. Mitigating this technical limitation, we applied the recent SUper-resolution SHadow Imaging technique (SUSHI) to astrocyte-labeled organotypic hippocampal brain slices, which allowed us to concurrently image the complex morphology of astrocytes and the ECS with unprecedented spatial resolution in a live experimental setting. Focusing on ring-like astrocytic microstructures in the spongiform domain, we found them to enclose sizable pools of interstitial fluid and cellular structures like dendritic spines. Upon experimental osmotic challenge, these microstructures remodeled and swelled up at the expense of the pools, effectively increasing the physical interface between astrocytic and cellular structures. Our study reveals novel facets of the dynamic microanatomical relationships between astrocytes, neuropil, and the ECS in living brain tissue, which could be of functional relevance for neuron-glia communication in a variety of (patho)physiological settings, for example, LTP induction, epileptic seizures or acute ischemic stroke, where osmotic disturbances are known to occur.