Changes of fight junction protein occludin expression in blood-brain barrier of rats after intracerebral hemorrhage

Abstract

Objective To investigate the changes of tight junction (TJ) protein occludin expression between the mierovascular endothelial cells of the blood-brain barrier (BBB) of rats after intracerebral hemorrhage (ICH). Methods Ninety-three male SD rats were randomly divided into normal control group and experimental group; rats of the experimental group were divided into 6 subgroups (6, 24, 48 and 72 h, and 7 and 14 d after intraeerebral hemorrhage). Rat models of intracerebral hemorrhage in the experimental group were established by autologous blood injection.Morphology of the brain tissues was detected by hematoxylin-eosin (HE) staining.The tight junctions between the microvascular endothelial cells of the BBB were sampled for ultrastructural observation using electron microcopy.Immunofluorescence and quantitative real time-PCR were used to analyze the protein and mRNA expressions of occludin,respectively. Results The brain edema was found in brain tissues around the hematoma. Necrosis and inflammatory infiltration could be found in perihematomal brain tissues and it was most obvious at 48 h after intracerebral hemorrhage. Obvious paracellular clefts were found between the adjacent endothelial cells in experimental groups. Strong expression of occludin was noted in the normal brain tissue; expression of occludin was positive 6 h after the injection and weak positive at 24, 48 and 72 h after the injection in the experimental groups.Quantitative real time-PCR showed that the mRNA expression of occludin in the experimental group was significantly reduced as compared with the normal brain tissue at 6,24,48 and 72 h after the injection with statistically significant difference (P＜0.05). Conclusion After intra-cerebral hemorrhage,as a major component of TJ of the BBB,occludin expression is down-regulated,which may be one of the most impotant molecular basis of disruption of BBB. Key words: Intra-cerebral hemorrhage; Blood-brain barrier; Tight junction; Occludin