Early Ischemic Brain Edema In Aqp4 Expression In The Law Of Magnetic Resonance Imaging Study Of The Mechanism

Objectve The aim of this study was to explore the rules of the aquaporin-4(AQP4) expression in the early stage of the ischemic brain edema. Methods 40 Wistar rats were divided into 3 groups randomly: control group(n=4), pseudo-operation group(n=12) and operation group(n=24). After the right middle cerebral artery of the rats was unilaterally occluded(MCAO), the animals in the latter two groups were perfused at a different interval of time: 15 min, 30 min, 1 h, 3 h, 6 h and 24 h, respectively(n1=2 and n2=4). The brain tissue of the rats were removed and fixed. Then the lesion side of the brains in all groups was examined with immunocytochemical analysis(IC,△S) and in situ hybridization (ISH,α). After that the imaging analysis of the AQP4 was made by means of Computer-aided Image Analyzer. Meanwhile, the histologic examination was performed under HE and TEM. Results There was a significant correlation between △S andα(r=0.949). There was no significant difference between control group and pseudo-operation group(t=1.67,P>0.05), but there was a significant difference between control group and operation group(t=16.8,P<0.01).The stained tissues for the AQP4 were predominantly observed in choroids plexus, ependyma, hypophysis, hippocampus and glial cells of the peri-infarcted cortex. Within 24 h after MCAO, the expression of the AQP4 presented two peaks with a plateau between them. At 15 min, 30 min and 1 h after occlusion, the AQP4 expression of the occluded side of the rat brain in the operation group increased rapidly. The corresponding histological changes at this stage were intracellular edema with integrity cell membrane. With the progress of the time(1 h~6 h), unlike the first stage, the expression of AQP4 increased slowly and showed a plateau. The pathologic changes in the stage were vasogenic brain edema. Whereas, there was the second peak of the AQP4 expression after 6 h. The major pathological changes of this stage were the necrosis of tissue. Conclusions The characteristics of the pathologic changes in the acute ischemic brain tissue of the rat are gradual increase of intracellular edema, then emergence of the vasogenic edema, and finally, appearance of the necrosis. The results imply that there is a significant correlation between AQP4 expression and acute ischemic brain edema. The up-regulated of AQP4 expression might play a key role in intracellular edema and necrosis of the ischemic brain edema. It, especially, maybe one of the important causes of the intracellular edema. There is no relationship between the AQP4 expression and the vasogenic brain edemaKey words Brain edema;Cerebral ischemia;Animal;Laboratory;Pathology;Aquaporin-4...