褪黑激素对小鼠缺血/再灌注损伤脑组织ATF-6影响

EFFECT OF MELATONIN ON ATF-6 IN MOUSE BRAIN TISSUE WITH ISCHEMIA/REPERFUSION INJURY

目的探讨褪黑激素(Melatonin)能否通过抑制内质网应激相关蛋白激活转录因子-6(ATF-6)对小鼠脑缺血/再灌注(I/R)损伤发挥保护作用。方法将36只C57BL/6J小鼠随机分为假手术组(Sham组)、I/R组、I/R+生理盐水(NS)组及I/R+Melatonin组,各9只。使用线栓法建立大脑中动脉I/R损伤模型,腹腔注射生理盐水作为I/R+NS组,腹腔注射Melatonin作为I/R+Melatonin组。采用2,3,5氯化三苯基四氮唑(TTC)染色观察各组小鼠脑组织梗死面积,HE染色观察各组小鼠脑组织形态,Western blot法检测脑组织中ATF-6及其下游靶点C/EBP同源蛋白(CHOP)的表达。结果与Sham组相比,I/R组出现明显梗死区域,I/R+Melatonin组梗死面积明显减小(F=30.60,P<0.01);与I/R组相比,I/R+Melatonin组神经细胞排列紊乱和凋亡显著改善,I/R+Melatonin组ATF-6及CHOP表达显著降低(F=56.11、225.50,P<0.01)。结论I/R损伤后,Melatonin通过抑制ATF-6及其下游信号通路CHOP蛋白的表达发挥神经保护作用。

Objective To investigate whether Melatonin can protect against ischemia/reperfusion(I/R)brain injury in mice by inhibiting the endoplasmic reticulum stress sensor activating transcription factor 6(ATF-6).Methods C57BL/6J mice were randomly divided into sham-operated(Sham)group,I/R group,I/R+normal saline(NS)group,and I/R+Melatonin group.The middle cerebral artery ischemia/reperfusion injury model was established using the suture method.Saline was injected intraperitoneally for the I/R+NS group and Melatonin was injected intraperitoneally for the I/R+Melatonin group.The infarct area was observed by 2,3,5-triphenyltetrazolium chloride(TTC)staining,the morphology of brain tissue was observed by hematoxylin-eosin(HE)staining,and the expression of ATF-6 and its downstream target C/EBP homologous protein(CHOP)in brain tissue was measured by Western blot.Results Compared with the Sham group,infarct area was observed in the I/R group,but significantly reduced in the I/R+Melatonin group(F=30.60,P<0.01).The I/R+Melatonin group showed significant improvements in neuronal disarray and apoptosis and significant reductions in the expression of ATF-6 and CHOP,as compared with the I/R group(F=56.11,225.50;P<0.01).Conclusion For cerebral I/R injury,Melatonin exerts neuroprotective effects by inhibiting the expression of ATF-6 and CHOP in its downstream signaling pathway.