Abstract Objective：To study the influence and mechanism of calpain inhibitor calpeptin in neuron apoptosis of hippocampal CA1 section in rats with focal cerebral ischemia-reperfusion. Method：128 health adult male SD rates were selected as the research animals.They were divided into the MACO group，the calpeptin group，the DMSO group and the sham group.The left middle cerebral artery（MCA） occlusion model was performed.2 hours after the left middle cerebral artery occlusion，recirculations of 6，12，24 hours and 48 hours were given to the rates.6，12，24 hours and 48 hours after the recirculations，the neurological functions of the rats were evaluated，immunohistochemistry was used to detect the expression of caspase-3 in hippocampal CA1 section and the neuronal apoptosis in hippocampal CA1 section was detected by the method of terminal deoxynucleotidyl transferase（TdT）-mediated dUTP nick end-labelling（TUNEL）. Result：The differences in the indexes between the MCAO group and the MACO group were not statistically significant（P>0.05）.The scores of neurological functions and the expression of caspase-3 in the calpeptin group were lower than those in the MCAO group and the MACO group，the differences were statistically significant（P<0.05）.12，24 hours and 48 hours after the recirculations，the situations of neuronal apoptosis in the calpeptin group were better than those in the MCAO group and the MACO group，the differences were statistically significant（P<0.05）.Conclusion：Calpeptin can reduce the neuronal apoptosis of hippocampal CA1 section in rats with ischemia-reperfusion injury and the mechanism may be related to the inhibition of the expression of caspase-3.
