抑制ERK1/2通路激活改善大鼠心房纤维化和缝隙连接蛋白40重构

Inhibiting activation of ERK1/2 pathway improves atrial fibrosis and connexin40 remodeling in rats

目的探讨ERK1/2通路抑制剂U0126对盐酸异丙基肾上腺素(ISO)诱导的大鼠心房纤维化和缝隙连接蛋白40(Cx40)重构的影响。方法将32只雄性SD大鼠随机等分为空白对照组、DMSO组、ISO[5 mg/(kg.d)]+DMSO组(模型组)和ISO[5 mg/(kg.d)]+U0126[0.5 mg/(kg.d)]+DMSO组(干预组)。每组1次/d给予相关试剂,连续7 d后处死大鼠并取心肌组织。用放射免疫法测血管紧张素Ⅱ(AngⅡ)含量;H-E和Masson染色法观察心肌纤维化程度;免疫组化法测定磷酸化丝裂原活化蛋白激酶激酶1/2(p-MEK1/2)、磷酸化细胞外信号调节激酶1/2(p-ERK1/2)以及Cx40的表达。结果 (1)空白对照组[(242.133±4.870)ng/L]与DMSO组[(239.412±1.795)ng/L]的AngⅡ含量差异无统计学意义,而模型组[(500.250±8.869)ng/L]和干预组[(498.695±9.340)ng/L]的AngⅡ含量较空白对照组与DMSO组均升高,差异有统计学意义(P均<0.01)。(2)空白对照组与DMSO组无心房纤维化,而干预组心房纤维化程度较模型组减弱(P<0.01)。(3)空白对照组与DMSO组中p-MEK1/2和p-ERK1/2的含量差异无统计学意义,模型组中两者含量较空白对照组与DMSO组均增加(P均<0.01),干预组中两者含量与空白对照组和DMSO组比较差异均无统计学意义,而与模型组比较差异有统计学意义(P<0.01)。(4)空白对照组与DMSO组中Cx40含量差异无统计学意义且呈线性分布于心肌细胞闰盘处,模型组中Cx40含量较空白对照组和DMSO组均减少(P均<0.01)且分布无规律性,而干预组中Cx40含量与空白对照组和DMSO组比较差异均无统计学意义且部分呈线性分布于心肌细胞闰盘处;干预组中Cx40含量减少程度较模型组减弱(P<0.01),且部分呈线性分布于心肌细胞闰盘处。结论心肌组织中AngⅡ含量长期升高可能参与了心房纤维化的形成和Cx40重构,U0126通过抑制ERK1/2通路激活可有效改善心房纤维化程度和Cx40重构。

Objective To investigate the effects of extracellular signal-regulated kinase 1/2（ERK1/2） pathway inhibitor U0126 on isopreterenol（ISO）-induced atrial fibrosis and connexin 40（Cx40） remodeling in rats.Methods Thirty-two male SD rats were evenly randomized into control group,DMSO group,ISO（5 mg/）＋DMSO group（fibrosis group）,and ISO（5 mg/）＋U0126（0.5 mg/）＋DMSO group（U0126-treated group）.The corresponding reagents were given to each group once a day and the rats were killed and the myocardial tissues were collected after 7 d.The AngⅡcontents in the myocardial tissues were measured by radioimmunoassay;H-E staining and Masson staining were applied to measure the degree of atrial fibrosis;p-MEK1/2,p-ERK1/2,and Cx40 were detected by immunohistochemistry method.Results（1） The contents of AngⅡ were similar between control group（[242.133±4.870] ng/L） and DMSO（[239.412±1.795] ng/L） group（P0.05）.Compared with the above two groups,AngⅡ contents in fibrosis group（[500.250±8.869] ng/L）and U0126-treated group（[498.695±9.340]ng/L） were significantly increased（P all0.01）.（2） Control group and DMSO group had no atrial fibrosis;the degree of atrial fibrosis in U0126-treated group was significantly lower than that in the fibrosis group（P0.01）.（3） p-MEK1/2 and p-ERK1/2 expressions were similar in control group and DMSO group（P0.05）,and those in the fibrosis group were significantly increased compared with control group and DMSO group（P0.01）;the expression in U0126-treated group was similar to those in the control group and DMSO group（P0.05）,and was significantly decreased compared with the fibrosis group（P0.01）.（4） The contents of Cx40 were similar between control group and DMSO group（P0.05）,and Cx40 was distributed in myocardial cell intercalated disc in a linear manner.The content of Cx40 was significantly reduced（P0.01） in the fibrosis group compared with the control group and DMSO group,with Cx40 distributed in disorder.The content of Cx40 in U0126-treated group was similar to that in the control group and DMSO group（P0.05）and most of the Cx40 was linearly distributed in myocardial cell intercalated disc.Meanwhile,the reduce degree of Cx40 content in U0126-treated group was significantly decreased than that in the fibrosis group（P0.01）,and some Cx40 was linearly distributed in myocardial cell intercalated disc.Conclusion Long-term Ang Ⅱ elevation in myocardium may be involved in atrial fibrosis and Cx40 remodeling,and U0126 can efficiently improve atrial fibrosis and Cx40 remodeling by inhibiting the activation of ERK1/2 pathway.