| Objective：Cerebral ischemia reperfusion injury (CIRI) refers to the function and structure ofbrain cell worsen after the ischemic brain tissue regaining blood supply, which is causedby a variety of mechanisms may be involved in a series of cellular and molecularchanges in the adjustment process and the complexity of the pathophysiologicalprocess.Angiotensin Ⅱ (Ang Ⅱ) is an important multifunctional vasoactive substances inthe renin angiotensin aldosterone system (RAAS). It can act on specificmembrane bound receptors, and almost all biological effects of RAAS currently knownis done by Ang Ⅱ with the corresponding receptors, which are divided into Ang Ⅱreceptor type1receptor (AT1receptor) and Ang Ⅱ type2receptor (AT2receptor). Inmany cases, the biological effects and signal transduction pathways mediated by Ang Ⅱbinding AT2receptor and Ang Ⅱ binding AT1receptor have antagonistic effects, suchas proliferation versus anti proliferation, cell division versus differentiation andapoptosis, and vasoconstriction versus diastolic. In the immature brain, AT2receptorsexpress abundant and distribute widely, mainly in the central structures and the limbicsystem, concerning in the motor, sensory, and learning, but in adult rats, the AT2receptors in these region are significantly reduced. Previous studies showed that theAT2receptor in nerve tissue can promote cell differentiation and regeneration, therebypromoting recovery of neurological function.In this study, establishing rat middle cerebral artery occlusion (MCAO) model toobserve the expression of AT2receptors and the related factors in cerebral ischemia reperfusion injury brain tissue, and discussing the effects and the possiblemechanisms of AT2receptor in cerebral ischemia reperfusion injury, then furtherexploring the effects and the possible mechanisms of candesartan in cerebralischemia reperfusion injury, so as to providing a new direction and theory for thetreatment of cerebral ischemia reperfusion injury.Methods：1. Establishing MCAO model.2. Detect cerebral infarction volume by TTC staining.3. Immunohistochemistry was used to detect brain AT2receptor, IL1β, TNF α,IL10, c fos, c jun and middle cerebral artery PCNA, α SM actin expression.4. HE staining cross section of the middle cerebral artery intima, media area andmade the film with the area ratio.5. Real time PCR detection of brain tissue Bcl2mRNA、Bax mRNA expression.6. Western blot analysis of brain tissueBcl2、Bax protein expression.7. Statistical analysis: Using SPSS11.5statistical software for statistical analysis,all data were expressed as mean±standard deviation, analyzed by Student t test,Differences were considered significant at P＜0.05.Results：1. Immunohistochemical detection AT2Receptor description AT2Receptorsinvolved in the cerebral ischemia reperfusion processes: AT2receptors expressionin brain tissue volume began to increase at1days reperfusion (P <0.05), reached a peakat the first seven days, and at the10days the expression level decreased gradually.2. Immunohistochemical detection IL1β, TNF α and IL10expressiondescription immune and inflammatory reactions involved in the cerebralischemia reperfusion processes: Compared with sham group, I/R group increasedbrain tissue expression of IL1β (P <0.05), TNF α expression was increased (P <0.05),IL10expression was increased (P <0.05).3. Immunohistochemical detection of middle cerebral artery PCNA andα SM actin expression, HE staining cross section of the middle cerebral artery intima, media area and made the film with the area ratio（I/M）, with thedescription of the cerebral ischemia reperfusion can cause blood arterial intimalhyperplasia, leading to vascular stenosis: comparison with the sham group, I/R groupincreased PCNA expression in the brain (P <0.05), α SM actin expression wasdecreased (P <0.05); IN I/R group, cerebral artery intima cross sectional I/M valueincreased (P <0.05).4. Immunohistochemistry was used to detect c fos, c jun expression, RTPCR detection of Bcl2mRNA, Bax mRNA and Western blot detection of Bcl2,Bax protein expression changes involved in apoptosis described cerebral ischemiaand reperfusion: Compared with sham group, I/R group decreased relative expressionof Bcl2mRNA in brain tissue (P <0.05), the relative expression of Bax mRNAincreased (P <0.05); relative expression of Bcl2protein decreased (P <0.05), therelative expression of Bax protein increased (P<0.05); c fos expression increased (P<0.05), c jun expression increased (P <0.05).5. Immunohistochemistry was used to detect AT2receptor expression andTTC staining to detect the brain infarct volume in different groups illustratingAT2receptors play a protective role in cerebral ischemia reperfusion process:given CGP42112treatment, AT2receptor expression in brain tissue increased （*P<0.05vs. Control group), given PD123319treatment, AT2receptor expression in braintissue decreased（#P<0.05vs. Control group); given CGP42112treatment, the infarctvolume reduced （*P<0.05vs. Control group); given PD123319treatment, the infarctvolume expanded（#P<0.05vs. Control group).6. Immunohistochemistry was used to detect IL1β, TNF α and IL10expression changes in different groups show AT2receptor has neuroprotectionfunction by inhibiting the inflammatory response: given CGP42112treatment, IL1β decreased expression（*P <0.05vs. Control group), TNF α expression was decrease（*P <0.05vs. Control group), IL10expression was increased（*P <0.05vs.Controlgroup);given PD123319treatment, IL1β expression increased（#P <0.05vs. Control group), TNF α expression was increased（#P <0.05vs. Control group), IL10expressionwas reduced（#P <0.05vs. Control group).7. Immunohistochemistry was used to detect the middle cerebral arteryPCNA and α SM actin expression of different groups, HE staining cross section ofthe middle cerebral artery intima, media area and made the film with the arearatio（I/M） show that AT2receptor has neuroprotection by inhibiting vascularstenosis after revascularization: ischemic cerebral artery PCNA expression wasreduced after giving CGP42112treatment（*P <0.05vs. Control group), α SM actinexpression was increased（*P<0.05vs. Control group); given PD123319treatment, theischemic cerebral artery PCNA expression increased（#P<0.05vs. Control group),α SM actin expression decreased （#P<0.05vs. Control group); given CGP42112treatment, arterial intimal cross sectional I/M value decreased （*P<0.05vs. Controlgroup); given PD123319treatment, arterial intimal cross sectional I/M value increased（#P<0.05vs. Control group).8. Immunohistochemistry was used to detect c fos, c jun expression, RT PCRdetection of Bcl2mRNA, Bax mRNA and Western blot detection of Bcl2, Baxprotein expression in different groups show that AT2receptor has neuroprotectiveeffect by inhibiting neuronal apoptosis: given CGP42112treatment, the expression ofBcl2mRNA relative increased （*P<0.05vs. Control group), the relative expression ofBax mRNA reduced（*P<0.05vs. Control group); given PD123319treatment, therelative expression of Bcl2mRNA reduced（#P<0.05vs. Control group), an increasedin the relative expression of Bax mRNA（#P<0.05vs. Control group). given CGP42112treatment, the relative amount of Bcl2protein expression increased（#P<0.05vs.Control group), the relative decreased in the expression of Bax protein（#P<0.05vs.Control group); given PD123319treatment, the relative amount of Bcl2proteinexpression decreased（*P<0.05vs.Control group), the relative expression of Bax proteinincreased（*P<0.05vs.Control group).9. Detect the AT2receptor expression by Immunohistochemical and thecerebral infarction volume by TTC staining of different groups, Candesartan exerts its protective effect through promote AT2receptors expresse in the processof cerebral ischemia reperfusion: Candesartan can lead to increased of AT2receptorsexpression in brain tissu（eP＜0.05）；decrease the volume of cerebral infarc（tP＜0.05）.Conclusion1. After cerebral ischemia reperfusion, AT2receptors expression of brain tissueincrease.2. Cerebral ischemia reperfusion injury can induced immune inflammatoryresponse、ischemia artery stenosis after blood reconstruction and neural cell apoptosis inbrain.3. AT2receptors exerts its protective effect in the process of cerebral ischemiareperfusion，this protection may be realized through inhibiting immune inflammation、ischemia artery stenosis after blood reconstruction and neural cell apoptosis in brain.4. Candesartan have a protective effect in the process of cerebral ischemiareperfusion，this protection may be realized through promote AT2receptors expresse inthe brain tissue after reperfusion，then promote AT2receptor mediated by the nerveprotective effect. |
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