The Expression Of AQP9 In The Rat Model Of Focal Cerebral Ischemia And The Effect Of Methylprednisolone On Their Intervention

ObjectionCerebral edema in ischemic cerebrovascular disease is the most common complication i n cerebral ischemia caused mortality, high morbidity, ischemic brain edema formation mechanism has been a hot subject of neuroscience focuses.To investigate the relationship between the formation of ischemic cerebral edema and the changes of AQP9 expression during pathological course of ischemic cerebral edema in rats,and to preliminary discuss the role of AQP9 and its expression regulation mechanism by methyl prednisolone during ischemic cerebral edema.MethodsA total of 190 healthy adult SD rats were divided into two groups randomly,the ischemic group and the sham operation control group and regulation group MCAO(middle cerebral artery occluding)models were established by occluding unilateral middle cerebral artery(MCA)of the rats with the suture method.The operation procedure of the control group was as same as the ischemic group but without occluding unilateral MCA.The brains of the animals were taken out at interval times of 6h,24h,and 72h,respectively.Subsequently,the morphological changes were observed with HE staining.Brain water content(BWC)was measured by using wet-dry weighing method, and immunohistochemistry(IHC), RT-PCR.ResultsAfter operation,the morphological phenotype,BWC,content changes of AQP9 and its mRNA expression,content of cAMP were not significantly changed in the control group.While in the ischemic group,HE staining showed that the brain tissue had ischemic changes.The space around the neurons and capillaries became larger,some of the neurons showed necrosis phenotype,the nuclei were deeply stained or disappeared and the number of the neurogliocyte increased.The brain water content of ischemic brain tissue significant increased from MCAO 6h,and gradually increased along with the ischemic time extendence,and reached its high level at MCAO 72h.The results of IHC showed that the positive expression of AQP9 and were observed in the hippocampus,choroid plexes,supraoptic nuclei,brain cortex and other regions.The content of AQP9 and its mRNA was up-regulated and reached its peak at MCAO 72h.The expression of AQP9 protein was positively correlated with AQP9 mRNA(r=0.9068,p<0.05).The expression of AQP9 was correlated with BWC after MCAO(r=0.9139,p<0.05).The expression of AQP9 was positively correlated with the content changes of cAMP(r=0.7392,p<0.05)during the brain edemaFormation,and the expression of AQP9 protein was positively correlated with AQP9 mRNA(r=0.9055,p<0.05).The expression of AQP9 was correlated with BWC after MCAO(r=0.9006,p<0.05).The expression of AQP9 was positively correlated with the content changes of cAMP(r=0.7392,p<0.05) during MP intervention.ConclusionsBoth the expression enhancement of AQP9 and its mRNA were correlated with the content changes of cAMP after MCAO,which increased with brain edema aggravation.The results imply that the expression changes of AQP9 would have a close relationship with the formation of brain edema after MCAO. When the MP can reduce the effect to the overexpression of AQP9, then reduce the brain edema formation, suggesting that MP may reduce the expression of AQP9 to reduce edema.