Objective To investigate the changes of neural stem cells （NSCs） in the rat hippocampus after cerebral infarction （CI） and to evaluate the neurogenesis caused by the activation of NSCs. Methods CI models of rats were made and rats were assigned to 6 groups: sham-operated

1 day

3 days

7 days

14 days

and 28 days after CI. The dynamic expression of bromodeoxyuridine （BrdU）

polysialylated neural cell adhesion molecule （PSA-NCAM）

glial fibrillary acidic protein （GFAP）

and neuronal nuclear antigen （NeuN） were determined by immunohistochemistry and immunofluorescence staining. BrdU was used to mark the proliferated NSCs. PSA-NCAM was used to mark the plasticity of activated NSCs. GFAP and NeuN were used to mark the differentiated NSCs. Results Compared with the controls

the number of BrdU+ cells in the hippocampus increased significantly at 1 day after CI （P<0.05）

reached peak at 7 days after CI （P<0.05）

decreased but still elevated compared with the controls at 14 days after CI （P<0.05）

and nearly unchanged at 28 days after CI. The number of BrdU+/PSA-NCAM+ cells increased significantly at 7 days after CI （P<0.05）

reached peak at 14 days after CI （P<0.05）

and decreased but still elevated compared with the controls at 28 days after CI （P<0.05）. The number of BrdU+/PSA-NCAM+ cells was equal to 60% of the number of BrdU+ cells in all the same period. The number of BrdU+/NeuN+ cells in the hippocampus increased significantly at 14 days after CI （P<0.05） and reached peak at 28 day after CI （P<0.05）. The number of BrdU+/GFAP+cells in the hippocampus nearly unchanged after CI. Conclusion CI can stimulate the proliferation of inherent NSCs

and most proliferated NSCs may differentiate into neurons and represent neural plasticity.