The Comparative Study Of Proliferation And Differentiation On SVZ And SGZ In Adult And Aged Rat After Transient Focal Cerebral Ischemia

Objective: To investigate the temporal profile of proliferation and compare the difference of differentiation of SVZ and SGZ in adult and aged rats after transient focal cerebral ischemia, and analyse the role of cerebral ischemia and aging on neurogenesis.Materials and methods: The right middle cerebral artery of rats were occluded (MCAO) for 90 minutes to establish transient focal cerebral ischemia model. Neural necrosis was observed with hematoxylin and eosin (HE) staining. Using BrdU to label the S phase cells, immunohistochemical single and double staining with antibodies against BrdU, NeuN and GFAP were used to determine proliferation and differentiation of SVZ and SGZ in adult and aged rats after MCAO(3d,7d,14,21d,28d).Result: All the rats of experimental groups had contralateral hemiplegy after ischemia, neural necrosis could be observed in caudoputamen 3d after ischemia, and necrosis area increase sharply 7d after ischemia, at 14d the caudoputamen and parietal cortex shrinked and liquefied. These meant that the transient focal cerebral ischemia model was established successfully.Proliferative cells of SVZ and SGZ in aged rats were apparently less than those of adult rats under normal condition. Proliferation increased obviously in ipsilateral and contralateral SVZ and reached the peak at 7d in adult and aged rats after ischemia, but the proliferative cells of aged rats were strikingly less than those of adult rats. Proliferation of SGZ in aged rats increased at 7d and peaked at 14d after ischemia, but no obvious change was obversed in SGZ of adult rats. Results of immunohistochemical double staining indicated: In SVZ BrdU labeled cells with GFAP expression in aged rats(12.56%) were much more than those in adult rats(6.29%), but BrdU labeled cells with NeuN expression in aged rats (0.98%) were less than those in adult rats(2.49%). In hippocampus, only a few BrdU labeled cells with NeuN expression were obversed in ipsilateral GCL of adult rats, no double labeled cells in GCL of aged rats were detected.Conclusions: In SVZ and SGZ of the adult rat, neuronal progenitor proliferation decrease with aging.The transient focal ischemia stimulated neurogenesis of the adult and aged rat, the ability of neurogenesis of aged rat was much lower than that of the adult rat.Many diseases of nerve system attack the aged people easy, we must use the aged model to study the role of neural stem cells in these diseases.