Zhang Z G, Bower L, Zhang R L, Chen S, Windham J P, Chopp M
Department of Neurology, Henry Ford Health Sciences Center, 2799 West Grand Boulevard, Detroit, MI 48202, USA.
Brain Res. 1999 Oct 9;844(1-2):55-66. doi: 10.1016/s0006-8993(99)01886-7.
Early astroglial response to post-ischemic microvascular hypoperfusion may contribute to progressive cerebral microcirculatory impairment and ischemic neuronal injury. Using laser-scanning confocal microscopy and three fluorescent probes, we measured in three-dimensions cerebral microvascular plasma perfusion, astrocytic reactivity, and neuronal injury assessed by fluorescein isothiocyanate (FITC)-dextran, GFAP immunoreactivity, and microtubule associated protein-2 (MAP2) immunoreactivity, respectively, in rats subjected to 2 h of middle cerebral artery occlusion. Three-dimensional quantitative analysis revealed that 2 h of embolic ischemia resulted in a significant (P<0.05) reduction of cerebral microvascular plasma perfusion in the ipsilateral cortex and subcortex. Tissue within the ipsilateral cortex and subcortex with low plasma perfusion exhibited a significant (P<0.05) increase in GFAP immunoreactivity compared with the homologous contralateral tissue. Three-dimensional re-constructed images showed that prominent GFAP immunoreactive astrocytes surrounded large vessels with decreased plasma perfusion in downstream capillaries in the ipsilateral MCA territory when compared to the vessels in the contralateral homologous tissue. Triple fluorescence probe-stained sections showed that tissue with decreased plasma perfusion and with increased GFAP immunoreactivity was accompanied by a reduction of MAP2 immunoreactivity. The present study demonstrates that an impairment of microvascular perfusion induces an early increase in GFAP immunoreactivity, and reactive astrocytes may contribute to a further reduction of cerebral microvascular plasma perfusion. The three-dimensional quantitative imaging analysis used in the present study provides a means to investigate parenchymal cellular responses to changes of cerebral microvascular plasma perfusion after MCA occlusion.
早期星形胶质细胞对缺血后微血管灌注不足的反应可能导致进行性脑微循环障碍和缺血性神经元损伤。我们使用激光扫描共聚焦显微镜和三种荧光探针，分别在大脑中动脉闭塞2小时的大鼠中，通过异硫氰酸荧光素（FITC）-葡聚糖、胶质纤维酸性蛋白（GFAP）免疫反应性和微管相关蛋白2（MAP2）免疫反应性，三维测量脑微血管血浆灌注、星形胶质细胞反应性和神经元损伤。三维定量分析显示，2小时的栓塞性缺血导致同侧皮质和皮质下脑微血管血浆灌注显著（P<0.05）降低。与对侧同源组织相比，同侧皮质和皮质下血浆灌注低的组织GFAP免疫反应性显著（P<0.05）增加。三维重建图像显示，与对侧同源组织中的血管相比，同侧大脑中动脉区域下游毛细血管中血浆灌注减少的大血管周围有突出的GFAP免疫反应性星形胶质细胞。三重荧光探针染色切片显示，血浆灌注减少且GFAP免疫反应性增加的组织伴随着MAP2免疫反应性降低。本研究表明，微血管灌注受损会导致GFAP免疫反应性早期增加，且反应性星形胶质细胞可能导致脑微血管血浆灌注进一步降低。本研究中使用的三维定量成像分析提供了一种手段，用于研究大脑中动脉闭塞后脑微血管血浆灌注变化时实质细胞的反应。
