INDUCTION OF CYCLOOXYGENASE-2 MESSENGER-RNA AND PROTEIN FOLLOWING TRANSIENT FOCAL ISCHEMIA IN THE RAT-BRAIN

Expression of cyclooxygenase-2 (cox-2) mRNA and inducible heat-shock p rotein-70 (hsp-70) mRNA was studied with in situ hybridization techniq ues at 30 min and 4 h following 1 h transient middle cerebral artery ( MCA) occlusion in the rat brain. In addition, immunoreactivity for cox -2 was studied after 8 h of reperfusion. Induction of hsp-70 and cox-2 mRNA was found in the brain side ipsilateral to MCA occlusion. Hsp-70 mRNA was induced in the parietal cortex and striatum within the terri tory of the occluded MCA. Induction of cox-2 mRNA was particularly see n in cortical layer II in the brain side ipsilateral to MCA occlusion. At 30 min of reperfusion, areas showing cox-2 mRNA induction included the cingulate and frontal cortices located perifocally to the areas s howing hsp-70 mRNA induction, and the piriform cortex. At 4 h of reper fusion, induction of cox-2 mRNA was seen within the parietal cortex. A t 8 h of reperfusion, immunoreactivity for cox-2 was mainly seen in th e ipsilateral cortex. These results demonstrate that transient focal i schemia induces the expression of cox-2 mRNA and protein in discrete a reas of the rat brain during reperfusion, which might lead to local in creases of arachidonic acid metabolism