Expression Of AT2R~+Cells In The Ischemia-reperfusion Brain Tissue In Rats

Objectives:Immunohistochemistry staining were used in cerebral ischemia–reperfusion model of rat middle cerebral artery occlusion(MCAO) to observe thedynamic changes AT2R+cellular expression at different timing (time points) in theischemia-reperfusion tissue and discuss the relation between AT2R and cerebralischemia-reperfusion injury.Methods:42male adult health Sprague-Dawley rats, weighing220-250g, wereseparated into sham group and ischemia-reperfusion group randomly,model group wassperated into1day,3days,5days,7days,10days and14days six sub-group,eachgroup with6rats. In accordance with the Zea-Longa suture method rat (MCAO) modelwas induced.The shame group is operated without inserting suture.Rats with the scoreranging from1-3points in Longa5-point scoring were supposed to be successfulmodel,whose scores were recorded and which were recorded and which were acceptedto the experiment.Taking reperfused rat brain at lintided timing (sham group were24hpostoperatively).with the brain pole as the starting point to prduce coron section,thefollowing procedures are as below:1.Observe the brain ischemia-reperfusion injury byTTC (2,3,5-Triphenyl tetrazalium chloride) staining;2Observe pathological changes ofbrain tissue after the ischemia-reperfusion under HE(hematoxylin-eosin) staining;3.Observe AT2R+cellular expression fluctuation in the aspect of timing and space withimmunohistochemical staining, Observe each slice of ischemic region (mainly cerebralcortex) under200times microscopy.then photograph and statistically analyze thestained brown yellowAT2R+cells.Results:1. The Observeation of infarct volume in rats:After TTC staining of braintissue,white zone was not found in shame group,presenting red.Compered with sham group in the right cerebrum there is significant white infarction zone,in accordance withMCAblood supplying area.2. The pathological Observeation of ischemia-reperfusion tissue: In the shamgroup,they are the normal brain tissue cells with normal morphology structure,cleararrangement and without sign of rcellular interstitial edema. In the model group after3days of ischemia–reperfusion the structural disorder was found in the ischemic cortualtissue, with visible edema and degeneration in number of normal nervon, after7days ofischemia–reperfusion there is a dramatic decrease in number of normal nervon,in manynervons cytoplasmic-nucleic boundaries ase unclear,with nucleus condensation,nucleus dissolution and vacuoles can be seen after10days and14days.3. Dynamic observation of AT2R+cellur expression in ischemia–reperfusion in thebrain tissue: In the sham group, a small amount of AT2R+cells can be founded,through the analysis to the sham group at different time,the number of AT2R+cell wasno significant difference. In the observation of the slice of cerebral ischemic group,wecan found that a dramatic AT2R+cells expression after24h of ischemia-reperfusion inthe ischemic cortex; After3-5days of reperfusion numerous AT2R+cells were seendiffusely distributed in the cerebral cortex of ischemic penumbra,where cellularmorphology show nearly round, no significantly differentin cellular size,an aggregationof AT2R+cells in the perivascilar region are prominent,with the prolongation ofreperfusion timing, after7days of reperfusion has showen that the peak number ofAT2R+cells, whose expression location is transformed to the central necrotic zone, Inthe10、14days after reperfusion the number of positive cells slightly decreased.4. High magnification in each group AT2R+cell count: sham group was11.2±0.5个/HP; ischemia-reperfusion24hours was12.8+-3.2points/HP,3days was37.2±2.2个/HP,5days was42.2±2.3/HP,7days was52.8±3.6个/HP,10dayswas51.2±4.4/HP, and14days was47.4±2.4个/HP.Compared with the shamegroup,there is significantly increase of the number of positive cells and the significancedifference (P <0.01) in each modle group.Conclusions:1.AT2R+cells in ischemia-reperfusion expression begins24hours,7nadir topeak, then declined;2.AT2R+cells were abundantly expressed in ischemia brain tissue；3. AT2R+cells were involved in the ischemia-reperfusion brain damage.