| Stroke is one of the leading causes of mortality and morbidity,with astronomicalfinancial repercussions on health systems worldwide. Ischaemic stroke accounts forapproximately80–85%of all cases and is characterised by the disruption of cerebralblood flow and lack of oxygen to the affected area. However, there are few effectivemedications to treat ischemic stroke. the effectest clinic treatment is to restore the bloodsupply of the blocked vascular, which is also basic therapy way and may inducesubsequently the collateral damage: ischemia-reperfusion.The silent information regulator protein2（Sir2）is a widely-studied antiaging proteinfactor in the lower animals. Sirt3is a member of the mammalian sirtuin family that islocalized to mitochondria and plays a role in the control of the metabolic activity.Recently, Sirt3has been reported to be associated with the deregulating metabolism anddefensing oxidative stress damage mediated by oxygen free radicals through antioxidantmechanism.Anesthesia provides a strong guarantee for the surgery, and in recent years aincreasing number of studies have found that propofol was involved in organprotection.Propofol is one of the most popular anesthic in clinical cases. Propofol hasbeen demonstrated to ameliorate cerebral ischemic injury and attenuate changes inmultiple links of molecular reaction included in the paths to apoptosis. But there is fewresearches studying the preconditioning protective effects of propofol against focalcerebral ischemic reperfusion injury.Therefore,we conduct this research to identify thepreconditioning effect of propofol, therapeutic time window of propofol and provide theprobable mechanism for it. The morphological changes of apoptosis under differentduration of ischemia were detected by terminal deoxynucleotidyl transferase(TdT)-mediated dUTP-biotin in situ nick labeling staining, and the effect of propofol onapoptosis was observed. The expression of SIRT3in post-ischemia neurons and theinfluence of propofol was analyzed by immunochemistry staining.We divided theresearch into3parts.Part1: Evaluation of two kinds of neurological function rating systems on rat focal cerebralischemia models Objective: To compare the value of two kinds of neurological function ratingsystems,Garcia JH and Bederson, in evaluation of focal cerebral ischemia reperfusionmodel in rats.Methods:16rats model of the focal cerebral ischemia-reperfusion injury wasestablished with the suture method..Two kinds of rating systems were employed toevaluate neurological functions of rats at24h after ischemia reperfusion. The braininfarct volume percentage(BIVP) was then assessed after2％TTC staining following thelast neurological outcome evaluation． The correlations between neurological functionscores and BIVP were analyzed by SPSS l8.0．Result:15survived after focal cerebral ischemia reperfusion． Garcia JH scores andBIVP were negatively correlated (r=-0.930, P<0.001), Bederson scores and BIVPpositively correlated (r=0.794, P<0.001).Conclusion: Both Garcia JH and Bederson neurological scales can be used to evaluatefocal cerebral ischemia reperfusion model in rats．Garcia JH scoring system may besuperior to Bederson neurological scale.Part2: Protective effects of propofol preconditioning on focal cerebralischemia-reperfusion injury in ratsObjective:To investigate the protective effects of propofol Preconditioning (PC) onfocal cerebral ischemia-reperfusion(I-R) injury in rats．Methods:Fifty-six male Sprague-Dawley rats were randomly divided into7groups ofI-R，LM，PC-6h，PC-12h，PC-24h，PC-48h and PC-72h with8rats each. Propofol50mg.kg-1.h-1was given at6,12,24,48or72h before cerebral ischemia in the last fivegroups，Lipo-microspheres and0.9%saline1ml/kg were injected iv at the end of90min ischemia in groups LM and I-S respectively．A focal cerebral ischemia reperfusionmodel was induced by the middle cerebral artery intraluminal suture method.All animalswere subjected to the left middle cerebral artery occlusion for90min，followed byreperfusion for24h．The neurological deficit score (NDS) was measured at24h after I-R.The brain infarct volume percentage(BIVP) was then assessed after2％TTC stainingfollowing the last neurological outcome evaluation．Results:The NDS in group6,12,24or48h at24h after I-R was not only greatlyhigher than that in group I-R(P<0.05)，but the BIVP was reduced more than that in groupI-R(P<0.05)． Conclusion:Propofol preconditioning can protect rat brain against I-R injury. Thetherapeutic time window of propofol neuroprotection may be over48hours．Part3: The mechanism of protective effects of propofol preconditioning on focalcerebral ischemia-reperfusion injury in ratsObjective: To investigate the probable mechanism of protective effects of propofolPreconditioning (PC) on focal cerebral ischemia-reperfusion(I-R) injury in rats．Methods:Sixty-four male Sprague-Dawley rats were randomly divided into4groups：sham operation group(group S)，I-R group，LM group and PC-24h group with16ratseach. Propofol50mg.kg-1.h-1，Lipo-microspheres and0.9%saline1ml/kg wereinjected iv24h before cerebral ischemia in PC-24h， LM and I-S group，respectively． Focal cerebral ischemia reperfusion mode was induced by occlusion ofmiddle cerebral artery for90min followed by24h of reperfusion The neurologicaldeficit score (NDS) was measured at24h after I-R. The brain tissues were taken fordetermination of the brain water content，The dynamic changes on the cell counts ofSIRT3and apoptosis were determined by immunohistochemical method and TUNEL，respectively．Results: The NDS in PC-24h，LM and I-S group was lower than that in S group，while content of water group, the number of neuronal apoptosis and expression of SIRT3protein increased (all P<0.05). Compared with the group I-R and LM, The NDSincreased and expression of SIRT3up-regulated, significantly, content of water groupand the number of neuronal apoptosis decreased.Conclusion: Propofol preconditioning can reduce focal cerebral I-R injury. Theprotective mechanism might be related to the effect of preventing apoptosis throughunregulating expression of SIRT3. |
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