槲皮素对中脑动脉闭塞模型大鼠异常自噬和氧化应激的调节作用

Regulatory Effect of Quercetin on Abnormal Autophagy and Oxidative Stress in Rats with Middle Cerebral Artery Occlusion

目的:探究槲皮素对中脑动脉闭塞(middle cerebral artery occlusion,MCAO)模型大鼠自噬和氧化应激的影响。方法:将大鼠随机分为假手术对照组、模型组、尼莫地平10 mg/kg组和槲皮素25、50和100 mg/kg组。术前14 d,灌胃给予相应药物或生理盐水,每天1次。除假手术对照组外,采用线栓法建立大鼠MCAO模型,24 h后处死大鼠。采用Bederon法对大鼠神经功能学进行评分,干湿重法检测脑组织含水量;HE染色检测脑组织病理情况;ELISA法检测脂质过氧化物含量;Western blot检测自噬相关蛋白的表达和腺苷酸活化蛋白激酶(adenosine monophosphate activated protein kinase,AMPK)/雷帕霉素靶蛋白(mammalian target of rapamycin,m TOR)/ULK1通路蛋白的表达。结果:与假手术对照组比较,模型组大鼠脑组织含水量、病理评分、LDH、MDA含量明显增高,SOD含量明显降低,Beclin1、Bax、p-AMPK、p-ULK1蛋白明显上调,p62、Bcl-2、p-mTOR蛋白明显下调,LC3Ⅱ/LC3Ⅰ比值明显降低。与模型组相比,槲皮素组剂量依赖地使大鼠神经功能学评分和脑组织含水量降低,且脑组织病理损伤明显得到改善;乳酸脱氢酶和MDA含量明显降低,SOD活性则升高;Beclin1、LC3Ⅱ/LC3Ⅰ和Bax蛋白表达水平明显下调,而p62和Bcl-2蛋白表达水平则上调,p-AMPK和p-ULK1表达水平明显下调,而p-mTOR表达水平则明显上调。结论:槲皮素能缓解MCAO大鼠脑组织的异常自噬和氧化应激水平,与抑制调节AMPK/m TOR/ULK1信号通路有关。

Objective:To investigate the effects of quercetin(Que)on autophagy and oxidative stress in middle cerebral artery occlusion(MCAO)rats.Methods:Rats were randomly divided into the control(Ctrl)group,the model(MCAO)group,nimodipine(Nim)10 mg/kg group and quercetin dose groups(25,50 and 100 mg/kg).On the 14 th day before the operation,corresponding drugs or saline water were intragastrically administered once a day.Suture embolic method was used to establish MCAO rat model.24 hours after modeled,rats were sacrificed.Neurological function of rats was scored by Bederon method.Brain water content was measured by dry-wet weight method,brain pathology was detected by HE staining,lipid peroxide content was detected by ELISA,expressions of autophagy-related proteins and adenosine monophosphate activated protein kinase(AMPK)/mammalian target of rapamycin(mT OR)/ULK1 were detected by Western blot.Results:Compared with the sham operation group,the brain water content,pathological scores,levels of LDH and MDA were increased in the model group,SOD level was decreased,the levels of Beclin1、Bax、p-AMPK and p-ULK1 protein were significantly up regulated,levels of p62、Bcl-2、p-mTOR protein were significantly down regulated,the LC3Ⅱ/LC3Ⅰrate was decreased in the model group.Compared with the model group,the neurological score and water content of brain tissue in quercetin group were decreased,in dose dependant manner.The pathological damage of brain tissues was significantly improved.the activity of lactic dehydrogenase(LDH)and the content of malonaldehyde(MDA)in quercetin group were decreased,while the content of superoxide dismutase(SOD)was decreased.The expression levels of Beclin1,LC3Ⅱ/LC3Ⅰand Bax protein in quercetin group were increased,while the expression levels of p62 and Bcl-2 protein were decreased.In addition,the expression levels of p-AMPK and p-ULK1 in quercetin group were increased,while the expression levels of p-mTOR were decreased.Conclusion:Quercetin can alleviate abnormal autophagy and oxidative stress in brain tissues of MCAO rats,which may be related to the inhibition of AMPK/mT OR/ULK1 signaling pathway.