RESUMEN

Objective To investigate the protective effect of retigabine (a M-type potassium channel opener) on brains and its mechanism in male mice after acute cerebral ischemia reperfusion(I/R)injury.Methods Seventy male C57BL/6J mice were randomly divided sham-operated group (n=10),middle cerebral artery occlusion (MCAO) group (n=10) and prevention group (n=50) according to the random number table method;mice in the prevention group were then divided into XE991 (a M-type potassium channel blocker) group,RTG-treatment 0 h group,RTG-treatment 1 h group,RTG-treatment 3 h group,and RTG-treatment 6 h group (n=10).The MCAO models were established by suture method,and reperfusion was performed 90 min after cerebral ischemia.In RTG-treatment groups,a single dose of 10.5 mg/kg RTG was injected at the designated varying time points (0,1,3 and 6 h after the reperfusion);in XE991 group,a single dose of 3.0 mg/kg XE991 was injected after the reperfusion;mice in the sham-operated group and MCAO group received the same volume of saline.Twenty-four h after model making,infarct size was measured by TTC staining.HE staining was used to observe the morphological changes of neurons in hippocampal CA1 regions.The apoptotic neurons level and membrane protein CD40L expression in the ischemic penumbra were detected by TUNEL staining and Western blotting.Results In the sham-operated group,brain tissues had no obvious change,no infarction was observed,there was no CD40L expression,and TUNEL staining positive neurons were hardly found.(1) Cerebral artery territory infarction was visible in the MCAO group and intervention group;however,the infarction volume of the RTG-treatment groups was significantly lower than that in the MCAO group (P＜0.05);the infarction volume of the RTG-treatment 6 h group was increased as compared with that of the RTG-treatment 0 h group,RTG-treatment 1 h group,and RTG-treatment 3 h group,without significant difference (P＞0.05).(2) HE staining showed that hippocampal neurons were obviously swollen and necrotic in the MCAO group and XE991 group,while the pathological damages such as brain edema and neuron necrosis were ameliorated significantly in the RTG-treatment groups.(3) As compared with those in the MCAO group,the number of TUNEL staining positive neurons in the RTG-treatment 0 h group,RTG-treatrnent 1 h group,and RTG-treatment 3 h group and CD40L number in the RTG-treatment 0 h group and RTG-treatment 3 h group were decreased significantly (P＜0.05);as compared with that in the MCAO group,the number of TUNEL staining positive neurons increased significantly in the XE991 group (P＜0.05).Conclusion RTG has protective effect on cerebral I/R,and its mechanism might relate to reducing cell excitability and inflammation,thereby inhibiting cell apoptosis;these protection would be less effective when RTG is used outside a defined critical period of time.