艾司洛尔对大鼠脑缺血再灌注时p-ERK1/2表达的影响

Effect of esmolol on expression of phosphorylated extracellular signal-regulated kinase 1/2 during cerebral ischemia-reperfusion in rats

目的评价艾司洛尔对大鼠脑缺血再灌注时磷酸化细胞外信号调节激酶(p-ERK)1/2表达的影响。方法清洁级健康成年雄性SD大鼠48只,8月龄,体重200~250 g,按照随机数字表法分为3组(n=16):假手术组(Sham组)、脑缺血再灌注组(I/R组)和艾司洛尔组(E组)。采用夹闭双侧颈总动脉20 min,恢复灌注10 min,重复3次的方法制备大鼠脑缺血再灌注损伤模型。E组于缺血前30 min静脉输注艾司洛尔200 g·kg^-1·min^-1,输注时间1 h,输注30 min后制备模型;I/R组于缺血前30 min静脉输注等容量生理盐水;Sham组大鼠只分离双侧颈总动脉而不夹闭,于分离双侧颈总动脉后输注等容量生理盐水。于缺血前和再灌注1、3和7 d时采用Morris水迷宫实验测试认知功能,随后处死大鼠取海马,确定湿重/干重(W/D)比值,采用EB法检测大鼠血脑屏障通透性,采用RT-PCR法检测海马ERK1/2 mRNA的表达,采用Western blot法检测p-ERK1/2的表达。结果与Sham组比较,I/R组和E组再灌注1、3和7 d时逃避潜伏期及游泳距离延长,海马W/D比值和脑EB含量升高,海马ERK1/2 mRNA和p-ERK1/2表达上调(P<0.05);与I/R组比较,E组再灌注1、3和7 d时逃避潜伏期及游泳距离缩短,海马W/D比值和脑EB含量降低,海马ERK1/2 mRNA和p-ERK1/2表达下调(P<0.05)。结论艾司洛尔减轻脑缺血再灌注损伤,改善大鼠认知功能的机制与抑制p-ERK1/2表达上调有关。

Objective To evaluate the effect of esmolol on the expression of phosphorylated extracellular signal-regulated kinase 1/2(p-ERK1/2)during cerebral ischemia-reperfusion(I/R)in rats.Methods Forty-eight clean-grade healthy adult male Sprague-Dawley rats,were allocated into 3 groups(n=16 each)using a random number table method:sham operation group(Sham group),cerebral I/R group(I/R group)and esmolol group(E group).Cerebral I/R was induced by 3 cycles of 20-min occlusion of bilateral common carotid arteries followed by 10-min reperfusion in anesthetized rats.Esmolol 200 g·kg^-1·min^-1 was intravenously infused for 1 h starting from 30 min before ischemia,and the model was established after 30-min infusion in E group.The equal volume of normal saline was given at 30 min before ischemia in I/R group.Bilateral common carotid arteries were only isolated but not clamped,and the equal volume of normal saline was given after isolating bilateral common carotid arteries in Sham group.Learning and memory function was tested by Morris water maze test before ischemia and at 1,3 and 7 days of reperfusion.Rats were sacrificed after Morris water maze test,and the hippocampus was excised for determination of wet to dry weight ratio(W/D ratio),permeability of blood-brain barrier(using Evans blue method),expression of ERK1/2 mRNA(by real-time polymerase chain reaction),and expression of p-ERK1/2(by Western blot).Results Compared with Sham group,the escape latency and swimming distance were significantly prolonged at 1,3 and 7 days of reperfusion,the W/D ratio and EB content in brain tissues were increased,and the expression of ERK1/2 mRNA and p-ERK1/2 was up-regulated in I/R and E groups(P<0.05).Compared with I/R group,the escape latency and swimming distance were significantly shortened at 1,3 and 7 days of reperfusion,the W/D ratio and EB content in brain tissues were decreased,and the expression of ERK1/2 mRNA and p-ERK1/2 was down-regulated in E group(P<0.05).Conclusion The mechanism by which esmolol alleviates cerebral I/R injury and improves cognitive function is related to inhibiting the up-regulated expression of ERK1/2 in rats.