Cortical neurogenesis in adult rats after transient middle cerebral arteryocclusion

Background and Purpose-This study explored the possible occurrence of newly generated nerve cells in the ischemic cortex of adult rats after middle ce rebral artery occlusion and reperfusion. Methods-Nine- to 10-week-old male Wistar rats were subjected to 2 hours of middle cerebral artery occlusion by the monofilament method. Rats received repeated intraperitoneal injections of the cell proliferation-specific mark er 5-bromodeoxyuridine (BrdU) after stroke induction. Brain sections were p rocessed for immunohistochemistry with an avidin-biotin complex-alkaline ph osphatase and/or -peroxidase method. Brain sections processed with double-i mmunofluorescent staining were further scanned by confocal microscopy. Results-Interspersed among the predominantly newly formed glial cells, some cells were double labeled by BrdU and 1 of the neuron-specific markers, Ma p-2, beta -tubulin III, and Neu N, at 30 and 60 days after stroke onset. Th ese cells were randomly distributed throughout cortical layers II through V I, occurring with highest density in the ischemic boundary zone. Three-dime nsional confocal analyses of BrdU and the neuron-specific marker Neu N conf irmed their colocalization within the same cortical cells. Conclusions-This study suggests that new neurons can be generated in the ce rebral cortex of adult rats after transient focal cerebral ischemia. Cortic al neurogenesis may be a potential pathway for brain repair after stroke.