Piotrowska Alina, Winter Karsten, Carare Roxana O, Bechmann Ingo
Institute of Anatomy, Leipzig University, Leipzig, Germany.
Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
Front Aging Neurosci. 2020 Feb 11;12:15. doi: 10.3389/fnagi.2020.00015. eCollection 2020.
Vascular pulsations, contractions of vascular smooth muscle cells and breathing have been reported to foster movement and clearance of interstitial and cerebrospinal fluids from the brain. The aim of this study was to estimate the contribution of these vital functions. We compared the spread of an injected hydrophilic tracer (Fluoro-Emerald, a 10 kDa fluorescein-coupled dextran amine) in the brains of live anesthetized and sacrificed rats at 30 and 90 min after injection. To determine the overall pattern of distribution of tracers, we created 3D-reconstructions of the horizontal transections of the whole brain. Immunofluorescence staining with laminin and collagen IV was performed to determine the pattern of distribution of tracer in relation to the cerebrovascular basement membranes. We found that diffusion was widely restricted to the periventricular region in sacrificed rats with no spread to the contralateral hemisphere, while the bulk flow occurred along the vasculature and reached the surface and the contralateral hemisphere as soon as 30 min after injection in live anesthetized animals. The tracer appeared to be localized along the vascular basement membranes and along fiber tracts as reported previously. Thus, our data indicate that vital functions are essential for the remote movement of extracellular fluids within the cerebral parenchyma.
据报道，血管搏动、血管平滑肌细胞收缩和呼吸有助于脑间质液和脑脊液的流动与清除。本研究的目的是评估这些重要功能的作用。我们比较了注射亲水性示踪剂（荧光翡翠，一种10 kDa荧光素偶联葡聚糖胺）后30分钟和90分钟时，在活体麻醉大鼠和处死后大鼠脑中的扩散情况。为了确定示踪剂的总体分布模式，我们对整个大脑的水平切片进行了三维重建。用层粘连蛋白和IV型胶原进行免疫荧光染色，以确定示踪剂相对于脑血管基底膜的分布模式。我们发现，在处死后的大鼠中，扩散广泛局限于脑室周围区域，未扩散至对侧半球，而在活体麻醉动物中，注射后30分钟，大量液体沿血管流动并到达表面和对侧半球。如先前报道，示踪剂似乎定位于血管基底膜和纤维束沿线。因此，我们的数据表明，重要功能对于脑实质内细胞外液的远距离流动至关重要。
