Three-dimensional measurement of cerebral microvascular plasma perfusion, glial fibrillary acidic protein and microtubule associated protein-2 immunoreactivity after embolic stroke in rats: a double fluorescent labeled laser-scanning confocal microscopic study

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 fluore scent probes, we measured in three-dimensions cerebral microvascular plasma perfusion, astrocytic reactivity, and neuronal injury assessed by fluoresc ein isothiocyanate (FITC)-dextran, GFAP immunoreactivity, and microtubule a ssociated protein-2 (MAP2) immunoreactivity, respectively, in rats subjecte d to 2 h of middle cerebral artery occlusion, Three-dimensional quantitativ e analysis revealed that 2 h of embolic ischemia resulted in a significant (P < 0.05) reduction of cerebral microvascular plasma perfusion in the ipsi lateral cortex and subcortex. Tissue within the ipsilateral cortex and subc ortex 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 immuno reactive astrocytes surrounded large vessels with decreased plasma perfusio n 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 a nd with increased GFAP immunoreactivity was accompanied by a reduction of M AP2 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 parenchy mal cellular responses to changes of cerebral microvascular plasma perfusio n after MCA occlusion. (C) 1999 Published by Elsevier Science B.V. All righ ts reserved.