Role of AMP-activated protein kinase in neuronal apoptosis in hippocampus of aged mice during cerebral ischemia-reperfusion

Objective To evaluate the role of AMP-activated protein kinase (AMPK) in neuronal apoptosis in the hippocampus of aged mice during cerebral ischemia-reperfusion (I/R) . Methods Seventy-two male C57/BL6 mice, aged 18-20 months, weighing 34-36 g, were randomly divided into 3 groups (n=24 each) using a random number table: sham operation group (S group) , I/R group and AMPK inhibitor compound C group (CC group) . The cerebral ischemia was produced by 15 min transient occlusion of bilateral common carotid arteries followed by reperfusion.In group CC, compound C 20 mg/kg was injected intraperitoneally immediately after occlusion, while the equal volume of normal saline was given in I/R group.At 48 h of reperfusion, the mice were sacrificed, and the brains were immediately harvested for examination of pathologic changes in hippocampal CA1 region and for determination of neuronal apoptosis (using TUNEL) and expression of phosphor-AMPKα (p-AMPKα) and caspase-3 (by Western blot) . Results In I/R and CC groups, the examination showed the pathologic changes in hippocampal CA1 region, the disordered arrangement of pyramidal cells and the nucleus condensation.Compared with S group, the neuronal apoptotic rate was significantly increased, and the expression of p-AMPK and caspase-3 was up-regulated at 48 h of reperfusion in I/R and CC groups.Compared with I/R group, the expression of p-AMPK was significantly down-regulated, and no significant change was found in the neuronal apoptotic rate and caspase-3 expression in CC group. Conclusion AMPK is not involved in neuronal apoptosis in the hippocampus of aged mice during cerebral I/R. Key words: Protein kinases; Reperfusion injury; Brain; Aged; Apoptosis; Hippocampus; Neurons