Changes in Expression Level of Aquaporin-4 During Cerebral Ische- mia-Reperfusion Injury in Rats

Objective: To investigate the dynamic changes in expression level of aquaporin-4 (AQP-4) during cerebral ischemia-reperfusion injury and its correlation with cerebral injury and e-dema. Methods: The focal cerebral ischemia-reperfusion model in SD rats was established. Im-munohistochemistry staining was used to detect the cerebral AQP-4. Dynamic changes in neurological deficit scores, permeability of blood-brain barrier (BBB). and brain edema were recorded. Results :(1) The expression level of AQP-4 decreased quickly after the focal cerebral ischemia-reperfusion injury, and it reached the lowest level 12-24 h after the reperfusion. Then it increased slowly, and returned to normal till day 7 after the reperfusion; (2) The severest brain edema was 24-72 h after the reperfusion, while the highest permeability of the Evans blue was 24-72 h after the reperfusion; (3) The time point of the severest neurological deficit was 24 h after the reperfusion; (4) AQP-4 expression level was negatively correlated with neurological deficit scores (r = 0. 976 7, P =0. 023). Conclusions: (1) The rapid decrease of AQP-4 expression level during cerebral ischemia-reperfusion injury is a protective response of the human body to the cerebral injury. It has the effects of blocking the destruction of BBB, reducing vasogenic cerebral edema and cy-totoxic brain edema. (2) The regulation of the functions and expression level of cerebral AQP-4 after cerebral ischemia will become a new target in the treatment of cerebral ischemia-reperfusion injury. Key words: aquaporin-4; ischemia; reperfusion; brain edema; rats