小牛血清去蛋白对脑缺血-再灌注损伤模型大鼠血脑屏障的保护作用研究

Protective Effect of Deproteinised Calf Serum on the Blood-Brain Barrier in Rats with Cerebral Ischemia-Reperfusion Injury

目的探讨小牛血清去蛋白对脑缺血-再灌注损伤模型大鼠血脑屏障(BBB)的保护作用。方法将100只SD大鼠随机分为假手术组(A组,等体积0. 9%氯化钠溶液)、模型组(B组,等体积0. 9%氯化钠溶液)及小牛血清去蛋白低剂量组(C_1组,7. 5 mg/kg,按肽量计,下同)和高剂量组(C_2组,37. 5 mg/kg),灌胃给药,每天1次,连续10 d。以栓线法建立脑缺血-再灌注损伤模型。在脑缺血-再灌注24 h时测定大鼠缺血区脑组织伊文斯蓝(EB)含量,采用免疫组化法检测大鼠BBB带状闭合蛋白-1(ZO-1)表达水平,以光镜、电镜观察大鼠BBB超微结构,以硝酸镧示踪电镜观察大鼠脑缺血-再灌注48 h时BBB的通透性。结果与A组比较,B组大鼠缺血区脑组织EB含量显著增加,ZO-1阳性血管数显著减少(P <0. 05);大鼠脑间质及神经纤维肿胀,内皮细胞皱缩。再灌注0. 5 h时,内皮细胞间紧密连接处(TJ)可见镧颗粒; 2～6 h时,内皮细胞空泡变多,足突和基底膜分离; 12～24 h时,神经细胞出现变性、坏死、核溶解,基底膜变得不连续; 48 h时,神经细胞坏死数量明显增多,内皮细胞的完整性也逐渐受到破坏。与B组比较,C_1组和C_2组大鼠脑组织EB含量显著减少,C_2组ZO-1阳性血管数显著增加(P <0. 05); C_1组和C_2组大鼠BBB受损程度有所减轻。结论小牛血清去蛋白对脑缺血-再灌注损伤模型大鼠BBB有保护作用,其机制可能与稳定缺血区脑细胞和增强ZO-1表达有关。

Objective To investigate the protective effect of Deproteinised Calf Serum Enteric Capsules(DCSEC)on the blood-brain barrier(BBB)in rats with cerebral ischemia-reperfusion injury.Methods Totally 100 SD rats were randomly divided into the sham operation group(group A,equal volume of 0.9% Sodium Chloride Solution),model group(group B,equal volume of 0.9% Sodium Chloride Solution),DCSEC low dose group(group C1,7.5 mg/kg,according to the amount of peptide,the same below)and DCSEC high dose group(group C2,37.5 mg/kg),intragas trie administration,once a day for consecutive 10d.The models of cerebral ischemic al reperfusion injury were established by the thread-embolism method.The content of Evens blue(EB)in brain tissues of rats was measured at 24h after cerebral ischemia-reperfusion.The expression level of zonula occludens-1(ZO-1)in BBB was detected by immunohistochemistry staining method.The BBB ultrastructure of rats was observed by light and electron microscopy.The permeability of BBB was observed by lanthanum nitrate-tracing electron microscopy at 48h after cerebral ischemia-reperfusion.Results Compared with group A,the content of EB in the ischemic brain tissue of rats in group B was significantly increased,the numbers of ZO-1 positive vessels in group B were significantly decreased(P<0.05),the interstitium of brain and nerve fibers of rats swelled and endothelial cells shrank.Lanthanum granules were observed in the tight junction(TJ)among endothelial cells at 0.5h after reperfusion,the vacuoles of endothelial cells increased and the foot processes and basement membrane were separated from 2h to 6h.The degeneration,necrosis and nucleolysis of nerve cells were observed,and the basement membrane became discontinuous from 12h to 24h,neurons degenerated,necrotized,nucleolyzed and basement membrane became discontinuous.At 48h,the numbers of nerve cell necrosis were significantly increased,and the integrity of endothelial cells was gradually destroyed.Compared with group B,the content of EB in brain tissue of rats in group C1 and group C2 was significantly decreased,the numbers of ZO-1 positive blood vessels in group C2 were significantly increased(P<0.05),and the BBB damage degree of rats in group C1 and C2 was reduced.Conclusion DCSEC has protective effect on BBB in rats with cerebral ischemia-reperfusion injury,and its mechanism may be related to the stabilization of brain cells in ischemic area and the enhancement of ZO-1 expression.