CHANGES IN THE SOLUBILITY OF GLIAL FIBRILLARY ACIDIC PROTEIN AFTER ISCHEMIC BRAIN-DAMAGE IN THE MOUSE

In the present study, changes in the content of glial fibrillary acidic protein (GFAP) in mouse cortex were investigated at different time intervals after unilateral middle cerebral artery occlusion. The GFAP content was assessed semiquantitatively by ELISA and immunoblotting. GFAP immunoreactivity was determined for each animal separately in protein fractions obtained from the ipsilateral, lesioned cortex and the contralateral, unlesioned cortex. Changes in the GFAP content of the lesioned cortex with respect to that of the unlesioned cortex were calculated for each fraction individually. GFAP was detectable in all protein fractions with a significant amount recovered from the aqueous extracts. A pronounced increase in the GFAP content of the lesioned cortex was observed. As measured by ELISA, this increase was maximal 5 days after injury and significantly more pronounced for the soluble and the Triton X-100-soluble protein fractions (mean increase 7 days after lesion, 281.4 and 240.2%, respectively) than for the crude cytoskeletal fraction (mean increase, 153.3%). A small and transient increase in GFAP immunoreactivity was also found in all protein fractions prepared from the contralateral, unlesioned cortex. These results were confirmed by immunoblotting.