Effects of remifentanil postconditioning on apoptosis in hippocampal neruons in a rat model of cerebral ischemia-reperfusion

Objective To investigate the effects of remifentanil postconditioning on apoptosis in hippocampal neruons in a rat model of cerebral ischemia-reperfusion(I/R)and the mechanism involved.Methods Twentyfour male SD rats weighing 250-300 g were randomly divided into 4 groups(n = 6 each): sham operation group (group S);global cerebral I/R group(group I/R);remifentanil 0.6μg·kg- 1·min-1+global cerebral I/R group (group R1)and remifentanil 1.8μg·kg-1·min-1 + global cerebral I/R group(group R2).Global cerebral ischemia was induced by 10 min occlusion of bilateral common carotid combined with hypotension.In group R1 and R2,remifentanil at 0.6 and 1.8μg·kg-1·min-1 were infused for 5 min before ischemia respectively.The cognitive function was tested with Morris water maze and step-down tests from the day 3 to day 8 after reperfusion.When Morris water maze test was finished,rat brains were removed for HE staining and determination of the expression of caspase-3 in hippocampal CA1 region by immuno-histochemistry.Apoptosis in neurons in hippocampal CA1 region was detected by TUNEL assay.Results Compared with group S,the cognitive function was significantly decreased and the number of apopotic neurons in hippocampus CA1 region increased in group I/R,R1 and R2,and the expression of caspase-3 was up-regulated in group I/R(P＜0.05).Compared with group I/R,the cognitive function was significantly increased,the expression of caspase-3 was down-regulated,and the number of apopotic neurons in hippocampus CA1 region was significantly decreased in group R1 and R2(P＜0.05).Conclusion Remifentanil postconditioning can improve the cognitive function through down-regulating caspase-3 expression and inhibiting the apoptosis in hippocampal neruons in a rat model of cerebral I/R. Key words: Piperidines; Reperfusion injury; Brain; Cognition disorders