Objective:To investigate the expression and cellular localization of Nemo-like kinase(NLK) in hippocampus of rat following cerebral ischemia reperfusion(IR). Methods:Sixty adult male Sprague-Dawley rats were randomly assigned to two groups:sham-operated group and IR group. According to different observation time after surgery,IR rats were individed into six subgroups(1 h,4 h,8 h,1 d,3 d and 7 d groups). A middle cerebral artery occlusion (MCAO) model in adult rats was constructed. The expression changes of NLK and active Caspase-3 in hippocampus of rat following cerebral IR were detected by Western blot. The cellular location and possible biological behavior of NLK was investigated by immunohistochemistry and immunofluorescence staining. Results:Western blot result revealed that NLK expression gradually increased,reached a peak at 8 h after cerebral IR,then decreased,and finally increased. There were significant differences in NLK expression between sham-operated group and IR group at 8 h after reperfusion (P < 0.05). Moreover,Caspase-3 expression progressively increased and reached a peak at the 3rd day,then decreased. There were significant differences in caspase-3 expression between these two groups at the 3rd day after reperfusion(P < 0.05). Immunofluorescence staining showed that NLK expression was principally located in neurons,especially pyramidal neurons of CA1 area in the hippocampus. Conclusion:The expression of NLK remarkably increased after cerebral IR,suggesting that NLK was involved in the development of cerebral ischemia in adult rats.