Expression changes of the tight junction-associated proteins occludin and claudin-5 in the microvessel endothelia of cerebral ischemia rat

Objective To investigate the changs of the permeability of BBB and the expression of the tight junction-associated proteins occludin and claudin-5 in the microvessel endothelia of cerebral ischemia rat.Methods Rats were scheduled to undergo middle cerebral artery ischemia by intraluminal suture.The change of the permeability of BBB was detected using evans blue(EB)dyeing.The distribution of occludin and claudin-5 was observed by the application of immunohistochemistry,and the changes of mRNA and protein expression of occludin and claudin-5 were determined by RT-PCR and Western blot.Results 2 hrs after the cerebral ischemia,the permeability of BBB was significantly increased(P0.01),the tight junction-associated proteins occludin and claudin-5 were expressed positively in microvessel endothelial cells,and the levels of mRNA and protein expression of occludin and claudin-5 were significantly decreased compared with normal control(P0.01).Conclusion The increase of BBB permeability in cerebral ischemia may be related to the decrease of tight junction-associated proteins occludin and claudin-5.