Effects of remote ischemic-postconditioning on global cerebral ischemia-reperfusion injury in rats

Objective To investigate the effects of remote ischemic postconditioning (RIPoC) on global cerebral ischemia-reperfusion (I/R) injury in rats.Methods One hundred and twenty-eight male adult SD rats weighing 200-250 g were randomly divided into 4 groups ( n =32 each):sham operation group (group S),group I/R,group I/R + RIPoC and remote I/R group (group RI/R ).Global cerebral I/R was induced by four-vessel occlusion.Group I/R + RIPoC received 3 cycles of 15 min reperfusion followed by 15 min ischemia in bilateral femoral arteries at the beginning of cerebral reperfusion.The rats were sacrificed at 24 and 48 h of cerebral reperfusion,and brains were removed for determination of neuronal apoptosis (by TUNEL method) in hippocampal CA1 region and the parietal cortex,Bcl-2 and Bax expression (by Western blot) in hippocampal CA1 region.The superoxide dismutase (SOD) and catalase (CAT) activity and malondialdehyde (MDA) content in hippocampal CA1 region and the parietal cortex were also measured at 48 h of cerebral reperfusion.Morris water maze task was used to test the learning and memory function at 4 d of cerebral reperfusion,and the rats were sacrificed at 7 d of cerebral reperfusion,and brains were removed for determination of neuronal density in hippocampal CAl region and the parietal cortex.Results Cerebral I/R significantly increased the number of apoptotic neurons and MDA content,upregulated Bcl-2 and Bax expression,decreased neuronal density,SOD and CAT activity and learning and memory function in group I/R as compared with group S.RIPoC significantly attenuated these cerebral I/R-induced changes.Conclusion RIPoC could protect brain against global cerebral I/R-induced injury,and the mechanism may be related to inhibiting lipid peroxidation,regulating the balance between Bcl-2 and Bax and inhibiting apoptosis. Key words: Lower extremity ;  Reperfusion injury;  Brain;  Ischemic postconditioning