依达拉奉对POCD老龄大鼠海马ERK-CREB信号通路的影响

Effect of edaravone on ERK-CREB signaling pathway in hippocampus of aged rats with postoperative cognitive dysfunction

目的:评价依达拉奉对术后认知功能障碍(POCD)老龄大鼠海马细胞外信号调节激酶(ERK)-cAMP反应元件结合蛋白(CREB)信号通路的影响。方法:SPF级健康雄性SD大鼠60只,20月龄,体质量650~700 g,采用随机数字表法分为4组(n=15):对照组(C组)、POCD组(P组)、依达拉奉组(E组)和ERK抑制剂组(I组)。P组、E组和I组采用3%七氟烷麻醉下行剖腹探查术的方法制备大鼠POCD模型。E组和I组术前30 min时腹腔注射依达拉奉3 mg/kg,I组尾静脉注射ERK抑制剂PD980590.3 mg/kg。于术后3 d时行旷场实验测定大鼠自主运动功能,于术后3~7 d行Morris水迷宫实验评估大鼠认知功能。水迷宫实验结束后处死大鼠取海马组织,采用Western blot法检测磷酸化ERK(p-ERK)、磷酸化CREB(p-CREB)、突触素和突触后致密蛋白95(PSD-95)的表达,行高尔基染色记录海马CA1区神经元树突长度和树突棘密度。结果:与C组比较,P组大鼠术后逃避潜伏期延长,穿越原平台位置次数减少,海马p-ERK、p-CREB、突触素和PSD-95表达下调,神经元树突长度缩短,树突棘密度降低(P<0.05);与P组比较,E组大鼠术后逃避潜伏期缩短,穿越原平台位置次数增多,海马p-ERK、p-CREB、突触素和PSD-95表达上调,神经元树突长度和树突棘密度增加(P<0.05);与E组比较,I组大鼠术后逃避潜伏期延长,穿越原平台位置次数减少,海马p-ERK、p-CREB、突触素和PSD-95表达下调,神经元树突长度缩短,树突棘密度降低(P<0.05)。结论:依达拉奉改善老龄大鼠POCD的机制与激活ERK-CREB信号通路,改变海马突触可塑性有关。

Objective To evaluate the effect of edaravone on the extracellular signal-regulated kinase(ERK)-cAMP responsive element binding protein(CREB)signaling pathway in the hippocampus of aged rats with postoperative cognitive dysfunction(POCD).MethodsSixty SPF healthy male Sprague-Dawley rats,aged 20 months,weighing 650-700 g,were divided into 4 groups(n=15 each)using a random number table method:control group(group C),POCD group(group P),edaravone group(group E)and ERK inhibitor group(group I).The rats received laparotomy under 3%sevoflurane anesthesia to prepare POCD model in P,E and I groups.Edaravone 3 mg/kg was intraperitoneally injected at 30 min before operation in E and I groups,ERK inhibitor PD980590.3 mg/kg was injected via the tail vein in group I.The open field test was performed at 3 days after operation to evaluate the spontaneous activity of rats,then Morris water maze test was performed to evaluate the cognitive function of rats on 3-7 days after operation.The rats were sacrificed after the end of Morris water maze test,and hippocampal tissues were obtained for determination of the expression of phosphorylated ERK(p-ERK),phosphorylated CREB(p-CREB),synaptophysin and postsynaptic density protein 95(PSD-95)(by Western blot)and dendrite length and density of dendrites in hippocampal CA1 area(using Golgi staining).ResultsCompared with group C,the escape latency was significantly prolonged after operation,the number of crossing the original platform was reduced,the expression of p-ERK,p-CREB,synaptophysin and PSD-95 was down-regulated,and the dendritic length and density of hippocampal neurons were reduced in group P(P<0.05).Compared with group P,the escape latency was significantly shortened,the number of crossing the original platform was increased,the expression of p-ERK,p-CREB,synaptophysin and PSD-95 was up-regulated,and the dendritic length and density of hippocampal neurons were increased in group E(P<0.05).Compared with group E,the escape latency was significantly prolonged,the number of crossing the original platform was reduced,the expression of p-ERK,p-CREB,synaptophysin and PSD-95 was down-regulated,the dendritic length of hippocampal neurons was shortened,and the density of hippocampal neurons was decreased in group I(P<0.05).ConclusionsThe mechanism by which edaravone improves POCD may be related to activating ERK/CREB signaling pathway and changing synaptic plasticity in hippocampal CA1 region in aged rats.