大鼠脑缺血/再灌注损伤时X连锁凋亡抑制蛋白和Smac表达及神经调节素的干预作用

目的观察神经调节素-1β(NRG-1β)对缺血/再灌注后脑组织X连锁凋亡抑制蛋白(XIAP)和次级线粒体源性caspase激活剂(Smac)表达的影响,探讨NRG-1β对脑缺血/再灌注损伤的保护作用。方法成年健康♂Wister大鼠110只,随机分为3组:假手术组(n=10),对照组(n=50)和治疗组(n=50)。治疗组动物单剂量给予NRG-1β干预治疗。应用原位末端标记技术(TUNEL)检测细胞凋亡,免疫荧光双标法和免疫印迹法检测脑组织XIAP和Smac蛋白的表达。结果缺血/再灌注能诱导脑组织细胞凋亡,随着缺血时间的延长,凋亡细胞数明显增加,NRG-1β处理能明显减少脑组织皮质区和纹状体区凋亡细胞数(P<0.05)。缺血/再灌注可诱导XIAP和Smac蛋白的表达,NRG-1β处理能上调XIAP和下调Smac的表达,协调神经细胞中XIAP/Smac的比例(P<0.05)。结论脑缺血后给予NRG-1β处理,可能通过协调XIAP/Smac蛋白的表达水平,调节细胞凋亡的发展过程,避免神经元发生不可逆损伤,从而对缺血/再灌注损伤有积极的保护作用。

Impact of neuregulin on the expressions of XIAP and Smac in brain tissue of rats afteRcerebral ischemic reperfusion injury

Aim To investigate the effect of neuregulin-1β(NRG-1β) treatment on the expression of X-linked inhibitor of apoptosis protein(XIAP) and the second mitochondrial derived activator of caspases(Smac) in brain tissue after cerebral ischemic reperfusion injury and to explore the neuroprotection of NRG-1β in rats.Methods One hundred and ten adult healthy male Wistar rats were randomly selected into a sham-operated group(n=10),a control group(n=50) and a NRG-1β treatment group(n=50).Rats in the treatment group were injected intraperitoneally neuregulin-1β at a single dosage of 0.3 μg·kg-1.Cell apoptosis was determined by terminal deoxynucleotidyl transference-mediated biotinylated deoxyuridine triphosphate nick end labeling technique(TUNEL).With immumofluorescent double staining and Western blotting assay,the expressions of XIAP and Smac proteins were detected at given timepoints.Results Ischemia and hypoxia could induce cell apoptosis.With the duration of ischemia,the amount of apoptotic cells increased gradually and the treatment of NRG-1β could decrease the level of apoptisis cells in cortex and striatum compared with that in the control group(P<0.05).The expressions XIAP and Smac proteins increased after MCAO/R,and NRG-1β treatment could upregulate the expression of XIAP while downregulate Smac protein,and thus moderating the ratio of XIAP/Smac in neurons which existed significant difference in contrast to the control group(P<0.01).Conclusions NRG-1β may play an important role and avoid the irreversible injury by moderating the expression level of XIAP/Samc proteins and regulating the development of apoptosis after cerebral ischemic reperfusion in rats.