缺氧诱导因子1α参与大脑中动脉闭塞模型大鼠的脑损伤与脑保护

Hypoxia-inducible factor 1 alpha is involved in brain injury/protection in rats with acute cerebral infarction

背景:急性脑梗死是脑组织缺氧缺血性坏死,在中国已经成为各种死亡原因中的第一位。缺氧诱导因子1α在脑梗死的发生发展过程中发挥双重作用,因此其抑制剂在临床中最佳应用时间的确定尤为重要。目的:探讨缺氧诱导因子1α调控急性脑梗死大鼠脑损伤/脑保护作用研究。方法:雄性SD大鼠随机被分为3组:假手术组(仅分离颈总动脉)、术后24 h组、术后72 h组,后2组采用线栓法制备大鼠大脑中动脉闭塞(MCAO)模型。利用TTC、尼氏染色、IHC和Western-blot检测大鼠脑组织梗死体积、小胶质细胞形态、缺氧诱导因子1α、caspase3、白细胞介素1β和p-NF-κBp65蛋白表达水平,ELISA方法检测各组大鼠外周血中白细胞素6和肿瘤坏死因子α的分泌水平。实验方案经佳木斯大学附属第一医院实验动物伦理委员会批准(批准号:JMSU-210)。结果与结论:①与假手术组相比,大脑中动脉闭塞模型大鼠脑梗死面积明显增加,脑神经细胞损伤严重,排列紊乱且数量明显减少;但术后24 h组与术后72 h组之间无明显差异;②与假手术组相比,术后24 h组与术后72 h组大鼠脑组织中缺氧诱导因子1α、caspase 3、p-NF-κBp65和白细胞介素1β的表达均明显升高(P<0.05,P<0.01),外周血中白细胞介素6和肿瘤坏死因子α的分泌水平明显升高(P<0.01);但与术后24 h组相比,术后72 h组仅caspase 3蛋白表达显著下降,而白细胞介素6和肿瘤坏死因子α的分泌水平则显著升高;③结果说明,缺氧诱导因子1α参与了急性脑梗死发生后的脑损伤/脑保护过程,且二者之间具有明确的时间靶点:大脑中动脉闭塞后24-72 h。此时间靶点的确定可为临床缺氧诱导因子1α抑制剂的最佳使用时间提供充分的理论依据和治疗策略。

BACKGROUND:Acute cerebral infarction indicates hypoxic-ischemic necrosis in brain tissue,which has become the first cause of death in China.Hypoxiainducible factor-1αplays a dual role on the occurrence and development of cerebral infarction.Therefore,it is particularly important to use its inhibitor at immediate time in clinical therapy.OBJECTIVE:To investigate the effects of hypoxia-inducible factor-1αon the regulation of brain injury/protection in rats with acute cerebral infarction.METHODS:Male Sprague-Dawley rats were randomized into three groups:sham operation group(sham),MACO-24 h group,and MACO-72 h group.A middle cerebral artery occlusion(MCAO)model was prepared by thread embolization in the latter two groups.TTC,Nissl staining,immunohistochemical staining and western blot were used to detect infarct volume and microglia morphology in rat brain tissue,the expression levels of hypoxia-inducible factor 1α,caspase 3,interleukin-1βand p-NF-κBp65 were detected,and the secretion levels of interleukin-6 and tumor necrosis factor-αin rat peripheral blood.The study protocol was approved by the Animal Ethics Committee of the First Affiliated Hospital of Jiamusi University(approval No.JMSU-210).RESULTS AND CONCLUSION:Compared with the sham group,the cerebral infarction area in the MCAO groups was significantly increased,and the brain nerve cells were seriously damaged,arranged disorderly and reduced significantly in number.However,there was no significant difference between the MCAO-24 h group and the MCAO-72 h group.Compared with the sham group,the expression levels of hypoxia-inducible factor 1α,caspase3,p-NF-κBp65,and interleukin-1βin the brain tissue of the MCAO groups were significantly increased(P<0.05,P<0.01).The secretion levels of interleukin-6 and tumor necrosis factor-αwas significantly increased(P<0.01)in the peripheral blood.However,compared with the MCAO-24 h group,the expression of caspase 3 in the MCAO-72 h group was significantly decreased,while the secretion of interleukin-6 and tumor necrosis factor-αincreased.To conclude,hypoxia-inducible factor 1αparticipates in the brain injury/protection process after acute cerebral infarction,and the time target is determined as 24-72 hours after MCAO.The determination of the time target can provide a sufficient theoretical basis and therapeutic strategy for determining the optimal use time of clinical hypoxia-inducible factor-1αinhibitors.