Changes in Aquaporin-9 Expression and Blood-brain Barrier in the Brain of Rats after Focal Cerebral Ischemia

Objective:To explore the changes in aquaporin-9(AQP9) expression and blood-brain barrier permeability in ischemia.Methods:Sixty SD rats were divided into ischemic group(n=40) and sham-operation group(n=20) randomly.The ischemic group was made by occluding unilateral middle cerebral artery with the suture method.And the sham-operation group was not caused ischemia.The morphology was observed with HE staining,the blood-brain barrier permeability was determined by Evans Bule(EB) extravasation method,and the expression of AQP9 was assessed by immunocytochemistry assay,at interval times of 6 h,12 h,24 h,48 h,72 h after cerebral ischemia,respectively. Results:Light microscopy showed neuronal degeneration and necrosis,swelling of the vascular endothelial cells,enlarged space around the neurons and peri-vascular space,and the increased number of gliosis.At 6 hours after cerebral ischemia,brain tissue EB content began to increase,and reached its peak at 48 hours.AQP9 expression rose 6h after ischemia in a similar manner to EB content.There was a positive correlation between expression of AQP9 and BBB penetrability(r0.67,P0.05).Conclusions: The up-regulation of AQP9 expression might imply that AQP9 would have a close relation to the formation of brain edema after cerebral ischemia.