Effects of hemoglobin level on Rho kinase of endothelial cells and tight junction protein claudin-5 in blood-brain barrier of rats after intracerebral hemorrhage / 中华神经医学杂志

ABSTRACT

Objective To explore the effects of hemoglobin level on Rho kinase Ⅱ of endothelial cells and tight junction protein clandin-5 in blood-brain barrier (BBB) of rats after intracerebral hemorrhage (ICH).Methods Male SD rats were randomized into normal control group (n=18) and hemoglobin inducement group (n=72); hemoglobin inducement group was divided into 4 subgroups (24 and 48 h,and 3 and 7 d after surgery,n=18).Rat ICH models in the hemoglobin inducement group were established by hemoglobin injection into the brain tissues.The expression ofRho kinase Ⅱ of endothelial cells and phosphorylated myosin light chain protein in BBB were observed by immunohistochemical staining,and BBB permeability was evaluated by Evans Blue dye; The protein and mRNA expressions of claudin-5 in the perihematomal brain tissues were detected by immunofluorescence staining and real-time quantitative PCR.Results Immunohistochemical staining indicated that expressions of Rho kinase Ⅱ of endothelial cells and phosphorylated myosin light chain in BBB of normal control group were rare,and those in the hemoglobin inducement group were high; as compared with that in the normal control group,mean optical density of Rho kinase Ⅱ and phosphorylated myosin light chain proteins in the endothelial cells of BBB in hemoglobin inducement group increased significantly at 48 h and 3 d after inducement (P＜0.05).The permeation of Evans Blue in hemoglobin inducement group significantly increased (P＜0.05).Immunofluorescence staining showed that the expression of clandin-5 in hemoglobin inducement group was uncontinuous and low as compared with that in the normal control group at 24 and 48 h and 3 d after inducement.PCR showed that the mRNA expression of claudin-5 in hemoglobin inducement group was significantly lower than that in the normal control group at 24 and 48 h and 3 and 7 d after the inducement (P＜0.05).Conclusion After intracerebral hemorrhage,hemoglobin can lead to increased expression of phosphorylated myosin light chain,and reduce the expression of tight junction protein claudin-5 of BBB by increasing the expression ofRho kinase Ⅱ in endothelial cells of BBB,which may be an important mechanism in the disruption of BBB and the occurrence of brain edema after intracerebral hemorrhage.