DIFFERENTIAL EXPRESSION OF C-FOS, HSP70 AND HSP27 AFTER PHOTOTHROMBOTIC INJURY IN THE RAT-BRAIN

In situ hybridization and immunohistochemistry were used to examine th e expression of c-fos, Hsp70 and Hsp27 following photothrombotic injur y in the right fronto-parietal cortex of the rat. C-fos mRNA and prote in were detected in the entire cerebral cortex on the lesioned side. H sp70 mRNA accumulation was observed only adjacent and peripheral to th e site of the lesion. At 1 h after photothrombotic injury, Hsp70 expre ssion delineates the area of necrosis at 24 h after photothrombotic in jury. Hsp27 protein was observed in the ipsilateral cerebral cortex wi th the exception of the deep layers of the cingulate cortex. In additi on, while c-Fos immunoreactivity was localized in cell nuclei, Hsp27 i mmunoreactivity was detected in the cytoplasm of astrocytes. These res ults demonstrate that unilateral cortical injury induces changes in ge ne expression that vary according to cell type and brain region.