Effects of breviscarpin on GluR2 protein and mRNA expression in hippocampal CA1 neurons of rats following transient forebrain ischemia

Objective:To investigate the effects of breviscarpin on GluR2 protein and mRNA expression in hippocampal CA1 neurons of rats following transient forebrain ischemia.Methods:Twenty-five male SD rats weighed from 250～300 g were randomly divided into 5 groups(n=5 each):groupⅠ(sham operation),groupⅡ(ischemia /reperfusion for 2 days),group Ⅲ(ischemia /reperfusion for 4 days),group Ⅳ(breviscarpin combined with ischemia/reperfusion for 2 days),groupⅤ(breviscarpin combined with ischemia/reperfusion for 4 days).The rats of Ⅱ,Ⅲ,Ⅳand Ⅴgroup were subjected to transient but severe forebrain ischemia by permanently occluding the vertebral arteries and 24 hours later temporarily occluding the common carotid arteries for 10 minutes.GroupⅠ animals were treated identically,except that the carotid arteries were not occluded.The rats of Group Ⅳ and Ⅴ were injected with breviscarpin(45 mg /kg) in abdominal cavity at 30 min before ischemia.The other groups were injected with equal 0.9% NaCl saline at the corresponding time.For quantization of GluR2 protein /GluR2 mRNA expression,rats were anesthetized and decapitated and the hippocampal CA1 were removed 2 days and 4 days after cerebral ischemia.GluR2 protein expression was assessed by Western Blot.RT-PCR was performed to assess the expression of GluR2 mRNA.The density of the bands was analyzed.Signal intensities were normalized against the internal standard(Western blot by GAPDH,RT-PCR by β-actin).Results:The GluR2 protein and mRNA expressions of group Ⅱand Ⅲ were both lower than those of groupⅠ(P 0.01).But the expressions of group Ⅳ and Ⅴwere higher than those of groupⅡand Ⅲ at the corresponding time(P 0.01).Conclusion:Breviscarpin attenuates down-regulation of GluR2 protein and mRNA after forebrain ischemia,which may be one of the inportant reasons rescuing hippocampal CA1 neurons after forebrain ischemia by breviscarpin.