Spatiotemporal expression of Nogo-66 receptor after focal cerebral ischemia

NgR, the receptor for the neurite outgrowth inhibitor Nogo-66, plays a critical role in the plasticity and regeneration of the nervous system after injury such as ischemic stroke. In the present study, we used immunohistochemistry to investigate the regional expression of NgR in rat brain following middle cerebral artery occlusion (MCAO). NgR protein expression was not observed in the center of the lesion, but was elevated in the marginal zone compared with control and sham-operated rats. The cerebral cortex and hippocampus (CA1, CA2, and CA3) showed the greatest expression of NgR. Furthermore, NgR expression was higher in the ipsilesional hemisphere than on the control side in the same coronal section. Although time-dependent changes in NgR expression across brain regions had their own characteristics, the overall trend complied with the following rules: NgR expression changes with time showed two peaks and one trough; the ifrst peak in expression appeared between 1 and 3 days after MCAO; expression declined at 5 days; and the second peak occurred at 28 days.