Delayed c-fos proto-oncogene expression in the rat hippocampus induced by transient global cerebral ischemia: an in situ hybridization study

Abstract The relative levels of c-fos mRNA in individual neurons of the hippocampal formation of rats is dramatically increased following 20 min of cerebral ischemia induced by 4-vessel occlusion. After 24 h of recirculation, a number of scattered neurons in the dentate hilus became hybridization positive. This effect appeared to peak between 24 and 48 h. A few neurons in the pyramidal cell layer of CA1 expressed c-fos as early as 24 h, but the most intense labeling in this region was seen at 72 h of recirculation. These results correlate well with the known distribution of delayed ischemic necrosis in the brain.