Investigating the effects of the cromakalim pretreatment on the expression of aquaporin -4 and the blood -brain barrier permeability in acute cerebral ischemia/reperfusion injury mice

Abstract

Objective To investigate the effects of ATP-sensitive potassium channel openers (Cromakalim) on the expression of aquaporin-4 and permeability of blood-brain barrer (BBB) after cerebral ischemic/repeffusion. Methods Thirty healthy male Wistar rats were randomized into three groups for different conditioning, the sham-operated group(A,n=10), the cerebral I/R group(B,n=10),and the cerebral I/R+Cromakalim group (C,n=10). Intraluminal suture methods were applied to establish the middle cerebral artery occlusion(MCAO) model with occlusion 2 h and reperfusion 24 h. The neurobehavioral function was evaluated with Bederson's test, and the pathological changes were observed with hematoxylin-eosin(HE) staining. The water content of brain was evaluated by wet-dry weight method, and the expressions of IgG and AQP-4 in brain were observed by immunohistochemistry staining. Results In comparison with group A's water content(78.2±1.3 )% and expressions of IgG and AQP-4 (0.0±0.0,13.6±1.5) ,the expressions of IgG and AQP-4(2.4±0.4,19.8±1.9) and the water content (81.3±1.2)% in group B both were significantly higher (P<0.05). However,in group C,the water content (79.5±0.6)%was similar to group A( 78.2± 1.3 )%. Interestingly, the expressions of IgG and AQP-4( 1.1 ±0.2, 15.7± 1.2 ) of group C were higher than that of group A' s (P<0.05); compared with group B, The neurobehavioral deficit scores were obviously reduced, the expressions of IgG and AQP-4 (1.1 ±0.2,15.7±1.2) and the water content (79.5 ±0.6)% were significantly lower in group C (P<0.05).Conclusion Cromakalim maybe can alleviate cerebral edema via reducing permeability of blood-brain barrier and inhibit the expression of AQP-4 in cerebral ischemia/reperfusion mice. Key words: Ischemia-reperfusion injury; Cromakalim; AQP-4; Blood brain barrier