低频诊断超声联合脂氟显微泡开放小鼠血脑屏障的可逆性研究

目的探讨低频诊断超声联合脂氟显微泡开放小鼠血脑屏障(blood-brain barrier,BBB)的可逆性及伊文思蓝(Evans blue,EB)透过率。方法健康C57BL/6小鼠48只,随机分为对照组6只和观察组42只。观察组再随机分为0、0.5、1、2、3、8、10 h亚组各6只,低频诊断超声辐照同时经尾静脉注射脂氟显微泡1 mL/kg,并分别于超声辐照0、0.5、1、2、3、8、10 h经尾静脉注射质量分数2%EB溶液50 mg/kg;对照组不进行低频诊断超声辐照,经尾静脉注射1 mL/kg生理盐水后注射质量分数2%EB溶液50 mg/kg。注射1 h后处死小鼠取脑组织,观察脑组织蓝染深度及面积,采用紫外分光光度法定量分析脑组织EB含量。结果对照组及观察组8、10 h亚组未见脑实质蓝染,观察组0、0.5、1、2、3 h亚组辐照区脑实质均有不同程度蓝染,且1 h时蓝染深度最深、面积最大;观察组0、0.5、1、2、3 h亚组脑组织EB含量(45.43±2.89)、(50.94±1.25)、(79.79±1.12)、(51.55±1.20)、(31.60±1.77)μg/g]均高于对照组(8.32±0.12)μg/g](P<0.05),8、10 h亚组脑组织EB含量(8.34±0.09)、(8.31±0.07)μg/g]与对照组比较差异无统计学意义(P>0.05);观察组0、0.5、1 h亚组脑组织EB含量依次升高(P<0.05),1、2、3 h亚组脑组织EB含量依次降低(P<0.05)。结论低频诊断超声联合脂氟显微泡开放小鼠BBB呈动态可逆的过程,BBB在超声辐照后1 h开放程度最大,于超声辐射8 h恢复正常。

Reversibility of low-frequency ultrasound combined with microbubbles in blood-brain barrier opening in mice

Objective To explore the reversibility of low-frequency ultrasound combined with microbubbles in blood-brain barrier(BBB)opening and the permeability of Evans blue(EB)in mice.Methods Forty-eight healthy C57 BL/6 mice were randomly divided into control group(n=6)and observation group(n=42).Observation group was randomly redivided into 0,0.5,1,2,3,8 and 10 h subgroups according to the interval of injecting 2%EB 50 mg/kg into caudal vein after diagnostic low-frequency ultrasound irradiation,with 6 mice in each group.Control group was injected with 2%EB 50 mg/kg into caudal vein with no ultrasound irradiation.The mice were sacrificed 1 h after injecting EB to obtain the brain tissue.The depth and area of EB staining were observed.Ultraviolet spectrophotometry was used to analyze the content of EB.Results Blue staining of the brain parenchyma was not found in control group,8 h subgroup and 10 h subgroup,was various in 0,0.5,1,2 and 3 h subgroups,and was the deepest and in the largest area in 1 h subgroup.The content of EB was higher in 0,0.5,1,2 and 3 h subgroups((45.43±2.89),(50.94±1.25),(79.79±1.12),(51.55±1.20),(31.60±1.77)μg/g)than that in control group((8.32±0.12)μg/g)(P<0.05),and showed no significant differences in 8 and 10 h subgroups((8.34±0.09),(8.31±0.07)μg/g)compared with that in control group(P>0.05).The content of EB increased gradually in 0,0.5 and 1 h subgroups in turn(P<0.05)and decreased gradually in 1,2 and 3 h subgroups in turn(P<0.05).Conclusion Low-frequency ultrasound combined with microbubbles in BBB opening shows a dynamic reverse process.BBB opening is the largest in 1 h and returns to normal after 8 h of irradiation.