不同浓度七氟醚预处理对局灶性脑缺血再灌注损伤大鼠神经功能、Nrf2／ARE通路及凋亡相关蛋白表达的影响

Effects of different concentrations of sevoflurane on the neurological deficit, Nrf2/ARE pathway and apoptosis-related proteins in rats with focal cerebral ischemia/reperfnsion injury

目的：观察不同浓度七氟醚预处理对局灶性脑缺血再灌注损伤（ CIR）大鼠神经功能、神经细胞凋亡及核转录因子／抗氧化反应元件（Nrf2／ARE）通路的影响。方法60只健康雄性SD大鼠，采用随机数字表法分为假手术组（ Sham组）、脑缺血再灌注损伤组（ CIR组），脑缺血再灌注前吸入2％七氟醚组（ S1组），脑缺血再灌注前吸入3％七氟醚组（ S2组），每组15只。使用线栓法建立CIR大鼠模型，Sham组和CIR组吸入纯氧，S1组和S2组分别于脑缺血前6 h吸入七氟醚＋氧气混合气体60 min，再灌注24 h后对所有大鼠进行神经功能缺损评分，采用TUNEL技术检测脑皮质区神经细胞凋亡情况caspase－3的表达，免疫组化染色检测核因子（ NF）－κB蛋白表达。 Western blotting法检测转录因子NF－E2相关因子2（Nrf2）、血红素加氧酶1（HO－1）蛋白表达。结果与Sham组比较，其他3组caspase－3表达明显升高， Nrf2表达明显减少；与CIR组比较，S1组和S2组神经功能缺损评分、caspase－3和NF－κB表达、凋亡指数明显降低，Nrf2和HO－1表达明显增多， S1组和S2组比较无明显差异。结论七氟醚可有效抑制神经细胞凋亡对CIR大鼠产生保护作用，其主要作用机制可能是通过激活Nrf2／ARE信号并上调HO－1的抗氧化酶基因表达发挥抗氧化作用，抑制凋亡相关蛋白caspase－3和NF－κB的表达。

Objective To investigate the effects of different concentrations of sevoflurane on the neurological deficit, neuronal apoptosis and Nrf2/ARE pathway in rats with focal cerebral ischemia/reperfusion injury （ CIR ） .Methods Sixty male SD rats were randomly divided into a sham group, a CIR group and two sevoflurane treatment groups （ Groups S1 and S2） （15 in each group）.The model of CIR was established in rats by reversible middle cerebral artery occlusion. Both the sham and CIR groups were given oxygen alone.Groups S1 and S2 inhaled 2%and 3%of sevoflurane respective-ly, 6 hours before ischemia for 60 min followed by reperfusion for 24 hours.All rats were scored according to their neuro-logical deficit.The amount of caspase-3 in the cerebral cortex was examined by TUNEL.The quantity of NF-κB was measured by immunohistochemistry.The levels of Nrf2 and HO-1 in the brain tissues were detected by Western blot-ting.Results Compared with the sham group, the other three groups produced remarkably increased amounts of caspase-3 but decreased levels of Nrf2.Moreover, compared with the CIR group, those treated with sevoflurane presented sig-nificant reduction in neurological deficit scores, the amounts of NF-κB and caspase-3 but rise in the levels of HO-1 and Nrf2, despite no statistical differences between Groups S1 and S2.Conclusion Sevoflurane can protect rats from CIR through inhibition of neuronal apoptosis, which may be related with blockage of NF-κB and caspase-3 expression by activating the Nrf2/ARE pathway and up-regulating HO-1 gene.