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 acidi c protein (GFAP) in mouse cortex were investigated at different time i ntervals after unilateral middle cerebral artery occlusion. The GFAP c ontent was assessed semiquantitatively by ELISA and immunoblotting. GF AP immunoreactivity was determined for each animal separately in prote in fractions obtained from the ipsilateral, lesioned cortex and the co ntralateral, unlesioned cortex. Changes in the GFAP content of the les ioned cortex with respect to that of the unlesioned cortex were calcul ated for each fraction individually. GFAP was detectable in all protei n fractions with a significant amount recovered from the aqueous extra cts. A pronounced increase in the GFAP content of the lesioned cortex was observed. As measured by ELISA, this increase was maximal 5 days a fter injury and significantly more pronounced for the soluble and the Triton X-100-soluble protein fractions (mean increase 7 days after les ion, 281.4 and 240.2%, respectively) than for the crude cytoskeletal f raction (mean increase, 153.3%). A small and transient increase in GFA P immunoreactivity was also found in all protein fractions prepared fr om the contralateral, unlesioned cortex. These results were confirmed by immunoblotting.