Immunohistochemical detection of nitrotyrosine in postischemic cerebral cortex in gerbil.

We examined whether or not nitration of tyrosine residues takes place in the ischemic and postischemic reperfused brain. The nitration of tyrosine residues to produce nitrotyrosine is a sensitive marker elicited by peroxynitrite, a powerful oxidant formed by the reaction of nitric oxide (NO) with superoxide. Mongolian gerbils were subjected to 60 min ischemia induced by occlusion of the right common carotid artery (ischemia group), to 30 min recirculation following 60 min ischemia (reperfusion group) or to sham surgery (sham group). Immunohistochemical staining with polyclonal anti-nitrotyrosine antibody revealed the widespread and distinct occurrence of nitrotyrosine in cortical neurons on the reperfused side of the brain in the reperfusion group, while only partial or weak immunoreactivity was noted on the contralateral side. On the other hand, nitrotyrosine was not detected in the brain of the ischemia and sham groups. These findings suggest that nitration of tyrosine residues in various proteins may be closely associated with reperfusion injury of the brain.