EXPRESSION OF C-FOS AND INDUCIBLE HSP-70 MESSENGER-RNA FOLLOWING A TRANSIENT EPISODE OF FOCAL ISCHEMIA THAT HAD NONLETHAL EFFECTS ON THE RAT-BRAIN

Expression of c-fos and inducible hsp-70 mRNA was studied with in situ hybridization techniques at different times following an episode of m iddle cerebral artery (MCA) occlusion not resulting in any apparent le thal effect on the rat brain. hsp-70 and c-fos mRNA were found in the ipsilateral striatum and adjacent cortex. In the striatum, levels of h sp-70 mRNA increased from 1 to 2 and 4 h of reperfusion, whereas level s of c-fos mRNA decreased from 3. to 4 h of reperfusion. These results demonstrate that following non-lethal focal ischemia the brain areas within the MCA territory show high c-fos and hsp-70 mRNA expression re sponse, illustrating the concomitant induction of these mRNAs in cells that survive the ischemic insult.