Evaluation Of Blood-Brain Barrier Permeability And Initial Study On Change Of HnRNP A2/B1 After Cerebral Ischemia/Reperfusion In Rats

Part one:Evaluation of Blood-Brain Barrier Permeability After Cerebral Ischemia/Reperfusion In RatsObjective:①To establish an reasonable and practicable rat models for acute cerebral ischemia/reperfusion insult research.②To explore changes of blood brain barrier(BBB) and edema formation at early period after cerebral ischemia/reperfusion in rats.Methods:①The middle cerebral artery occlusion/reperfusion(MCAO/R) rat models were made by the modified suture-occuluded method of Longa occlision method.Cerebral infarction volumes were quantitated by TTC staining.②Male SD rats were randomly divided into sham-operated group and ischemia-reperfusion groups.The model of focal cerebral ischemia-reperfusion was induced by right middle cerebral artery occlusion(MCAO).After 2 h of temporary MCAO,rats were respectively subjected reperfusion of 3h,6h,12h,24h.Damage to the BBB was judged by extravasation of Evans Blue(EB) dye.and brain water content was determined by dry/wet weight method.Results:①Infarct volumes were clearly indicated by TTC staining.The MCAO/R rat models were successfully established.②At 3h of reperfusion after cerebral ischemia,the permeability of BBB began to increase (P＜0.05),reached the peak at 24h of reperfusion(P＜0.01).Compareing with left cerebral tissues,the content of EB in the right brain tissues were significant increased in ischemia-reperfusion groups(P＜0.05).As compared to sham-operated group,the concentration of EB in ischemia-reperfusion groups was increased(P＜0.05).The change pattern of brain water content was similar to that of BBB permeability.Conclusions:Integrality of the BBB was broken down at early period of cerebral ischemia/reperfusion,and exacerbated cerebral edema. These results suggested a key role of structure and function of BBB in early stage after cerebral ischemia/reperfusion insult.Part two:Initial Study on Change of heterogeneous nuclear ribonulcleoprotein(hnRNP) A2/B1After Cerebral Ischemia/Reperfusion In RatsObjective:To investigate the dynamic change of heterogeneous nuclear ribonulcleoprotein A2/B1(hnRNP A2/B1) expression in pallium,striate cortex, temporal lobe,pyriform cortex in rats following ischemia/reperfusion injury. Methods:Male SD rats were randomly divided into sham-operated group and ischemia-reperfusion groups.The model of focal cerebral ischemia-reperfusion was induced by right middle cerebral artery occlusion(MCAO).After 2 h of temporary MCAO,rats were respectively subjected reperfusion of 3h,6h,12h, 24h,48h.Sham operated rats not subjected to MCAO served as controls. Immunohistochemical method was performed to observe the change of hnRNP A2/B1 in cerebral cortex.Results:At 3h of reperfusion after cerebral ischemia, the hnRNP A2/B1 began to translocation from nuclear to cytoplasm,even to neurodendrite,growth cone of axon;reached the peak at 24h of reperfusion (P＜0.01).However,this phenomenon dramatically reduced to zero at 48h of reperfusion.HnRNP A2/B1 protein was significantly down-regulated from 3h to 24h after ischemia-reperfusion insult in cerebral ischemic pallium,striate cortex, temporal lobe,pyriform cortex(P＜0.01).However,expression of hnRNP A2/B1 protein was significantly up-regulated at 48h in cerebral cortex(P＜0.01 ).Conclusion:hnRNP A2/B1 maight be involved in regulating brain ischemia/reperfusion injury on post-transcriptional level.