| The mechanism on cerebral ischemic reperfusion ( CIR) is a complicated process with many factors , which is main relative to the reflect of oxidation and inflammation , calcium intoxication, brain edema (BE) , cellular apoptotic and so on, the BE is an important pathological link . BE after CIR has many reasons . It was discovered that the aquaporin (AQP) family are a group of selective water transport protein in epicyte that can enhance water permeability. Aquaporin - 4 ( AQP - 4 ) has mainly located at central nerve systemic glial epicyte , ependyma cell and choroidal, which plays an important role on water metabolism, distribution and osmotic pressure adjustment. In some central water metabolismic disease , such as acute water intoxication, AQP - 4 expression detected increasingly , but downgradulation AQP - 4 expression BE model, cerebral water content decreased in rats, edema had obviously lightened in glial cell region. This suggested that AQP -4 take part in the formation of BE,the same in ischemic BE as well. The AQP-4mRNA expression parallels to the formation and development of BE in cerebral middle artery occlusion ( CMAO) , the results supported the hypothesis that AQP -4 had participated in ischemic BE. We have done the experiment to explore the relation between AQP - 4 expression and BE , study AQP - 4 effect on formation and development of BE through evaluate AQP - 4 expression and deplore furtherly BE mechanism after CIR.Materials and Methods1. Materials1. 1 Reagents; Immunohistochemistry, using SABC method, first antibodyis rabbit anti mouse AQP -4 monoclonal antibody (working concentration is 1: 200). SABC kit.1.2 Animal and other materials: Wistar rat and so on.2. Methods2.1 Animal groupingWistar rats were distributed to three groups at random and that is normal control,sham operation and CIR group.2. 2 To make rat CMAO model used Zea Longa modified way, measure cerebral water content by dry - wet way and detect the level of AQP - 4 expression through immunohischemistry.Result1. The encephalic tissue section HE staining observed in light microscope The encephalic tissue cortical cells have normal form and structure in control , sham operative opposite side of ischemia groups. Neurons decrease,put in disorder,the peripheral diastema of cell widen. A lot of neurons become ischemia and necrosis, cytoplast swelling, cytoplasm staining blandly, karyoplast dissolve and structure not clear in frontal and parietal lobe cortex , infracortical medulla and basal ganglia region, and have many contract neurons in infarct peripheral region of ischemic reperfusion side.2. The change of brain water content after cerebral ischemic reperfusion The brain water content was increased markedly at 12 hours after reperfusion , its peak value occurred at 48 ~ 120 hours and it also had a high level at 168 hours. A significant difference in brain water content of ischemic reperfusion group was found compared with that of health lateral, sham operative group and control group respectively ( p < 0.005 ).3. The expression of AQP -4 after cerebral ischemic reperfusionThere was the expression of AQP -4 in the animal modals of the ischemic reperfusion groups, but not in the normal and filse operated groups. There was weak expression in cerebral neurons around the ischemic lesion occurred at 12h after reperfusion, raised obviously at 24h , reached peak at 72h and kept expres-sion after 168h.4. Correlation between the expression of AQP -4 and brain edema on cerebral ischemic reperfusion in ratsThe expression of AQP - 4 and the brain water content raised obviously 12h after cerebral ischemic reperfusion, peaked at 72h and kept the higher level after 168h. There was a positive correlation between the expression of AQP -4 and the brain water content (r =0.958 , p <0.001).DiscussionBE is an important pathological link of CIR nerve injury. BE may has a close relation with AQP - 4 after CIR. AQP is a kind of membrane ionophone discovered in recent decade. It is a main m...
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