Effect of β-aescinum natrium on ischemic cerebral edema and aquaporin 4 expression in rats

Objective To study the effect of β-aescinum natrium on cerebral edema and aquaporin 4(AQP4)expression after cerebral infarction in rats.Methods One hundred fifty male Sprague-Dawley rats,weighting between 240 and 300 g,were randomly allocated into β-aescinum therapy(n=60),control(n=60)and sham-operation(n=30)groups.The rats in all the groups were redivided into 5 subgroups according to the different time periods of brain ischemia,so that there were 12 rats in each subgroup of the therapy group and the control group,and there were 6 rats in each subgroup of the sham-operation group.The rats were killed by decapitation and the brains were taken out at 6 hours,day 1,3,5 and 7 after establishment of the model.The rat middle cerebral artery was occluded by the suture method,and the model of ischemic cerebral edema was established.The rats in the therapy group were injected β-aescinum natrium(5 mg·kg-1·d-1)intraperitoneally,while the rats in the control and sham-operation groups were injected the same amount of isotonic saline at the same time interval.The dry-wet weighing method was used to observe the dynamic changes of cerebral edema;the pathologic changes in cerebral infarction regions were observed by HE staining,and immunohistochemistry staining was used to detect the AQP4 expression in brain.Results ①The brain water content(BWC)began to increase in the ischemic side of hemisphere at 6 hours after cerebral infarction,it reached the peak at day 3,and then decreased gradually,but it was still higher than that in the sham-operation group at day 7.There was statistical significance between the therapy group and control group in BWC at different time points(F=30.704,F=36.703,all P0.01).The BWC in the infarcted hemisphere in the therapy and control groups was obviously higher than that in the sham-operation group at every point of time(all P0.01),and that of the therapy group was lower than the control group(P0.05 to 0.01).② The level of AQP4 expression increased in the infracted side at 6 hours after cerebral infarction,it reached the peak at day 3,and then decreased gradually,but it was still higher than that in the sham-operation group at day 7.There were significant differences between the therapy group and the control group at different time points(F=20.878,F=28.489,all P0.01).The AQP4 expression in the therapy group and control group was higher than that in the sham-ope-ration group at every point of time(all P0.01),and the AQP4 expression in the therapy group were significantly lower than that in the control group(P0.05 to 0.01).The level of AQP4 expression was positively correlated with BWC(r=0.972,P0.001).Conclusion β-aescinum natrium significantly reduces cerebral edema after cerebral infarction and inhibits AQP4 expression,and it may reduce cerebral edema through inhibiting of AQP4 expression.