抑制ERK1/2对大鼠脑缺血再灌注损伤的保护作用

Protective effetc of inhbition of ERK1/2 on rats after cerebral ischemia-repufusion injury

目的探讨抑制细胞外调节蛋白激酶(ERK)1/2对脑缺血再灌注(I/R)损伤大鼠的作用及对缝隙连接蛋白(Cx)40/Cx43异型缝隙连接表达以及核因子-κB(NF-κB)相关炎症因子p-IκBa、肿瘤坏死因子(TNF)-α及干扰素(IFN)表达的影响。方法选取成年雄性100只大鼠随机分为5组,每组20只:假手术组(仅暴露双侧颈总动脉而不夹闭);治疗组4 h组和治疗组8 h组(I/R后立即腹腔注射ERK1/2特异性抑制剂SCH772984,25 mg/kg);④溶媒组(I/R后立即腹腔注射溶媒二甲基亚枫);⑤模型组(阻断双侧颈总动脉血流30 min后,恢复血流,产生I/R损伤)。采用神经功能损伤程度量表(NSS)评分评估大鼠神经功能。采用干湿重法测定脑组织含水率。采用免疫印迹法测定损伤侧海马区皮质p-IκBa、TNF-α及IFN的表达,采用免疫共沉淀法检测Cx40/Cx43异型连接表达。结果模型组NSS评分脑含水率、p-IκBa、TNF-α、IFN及Cx40/Cx43异型连接的表达水平较假手术组均明显增高(P<0.05),SCH772984干预后,均明显下降(P<0.05)。结论抑制ERK1/2途径,可明显抑制Cx40/Cx43异型连接和NF-κB,减少炎症因子,缓解脑水肿,从而改善大鼠神经功能。

Objective To investigate the effect of inhibition of extracellular regulated protein kinase(ERK)1/2 on rats after the cerebral ischemia-repufusion(I/R) injury. Methods One hundred adult SD rats were randomly divided into 5 groups 20 animals each, i.e. sham operation;treatment groups 1 and 2 in which the animals received the intraperitoneal injection of ERK1/2 inhibitor SCH 772984(25 mg/kg) immediately after I/R and then were sacrificed 4 and 8 hours after I/R, respectively;vehicle group in which the animals received intraperitoneal injection of isovolumetic DMSO and then were sacrificed 8 hours after I/R;injury group in which the animals without receiving any treatment were sacrificed 8 hours after I/R. The cerebral I/R injury model was established by clipping bilateral common carotid arteries. The cerebral water content was measured by Hatashita wet-weight method in 10 rats of each group. The levels of p-IκBa, tumor necrosis factor-α(TNF-α), interferon(IFN) and Cx40/Cx43 heterotypic gap junction expressions were determined in the hippocampal tissues of 10 rats of each group by western blot and co-immunoprecipitation, respectively. Results Water content and levels of p-IκBa, TNF-α, IFN and Cx40/Cx43 heterotypic gap junction expressions were significantly lower in the treatment groups 1 and 2 than those in the vehicle and injury groups(P<0.05) and were significantly higher than those in the sham group(P<0.05). There were no significantly differences in the cerebral water content and the levels of p-IκBa, TNF-a, IFN and Cx40/Cx43 heterotypic gap junction expressions between both the treatment groups(P>0.05). Conclusion Inhibition of ERK1/2 may relieve the cerebral oedema and improve the neurological function which may be by down-regulation of Cx40/Cx43 heterotypic gap junction and p-IκBa protein expressions, then reducing the levels of inflammatory factors such as TNF-α and INF expressions in the rats after I/R injury.