七氟醚对老龄大鼠海马cAMP-PKA-CREB信号通路的影响

Effect of sevoflurane on hippocampal cAMP-PKA-CREB signaling pathway in aged rats

目的评价七氟醚对老龄大鼠海马环磷酸腺苷-蛋白激酶A-环磷酸腺苷反应元件结合蛋白(cAMP-PKA-CREB)信号通路的影响。方法健康老龄雄性SD大鼠60只,18月龄,体重600~750g,采用随机数字表法分为2组(n=30):对照组(C组)和七氟醚组(Sev组)。Sev组吸入2%七氟醚4h,C组吸入50%空氧混合气体(2L/min)4h。于麻醉前1~6d(训练期)及麻醉结束后1d时(C组于相应时点)行Morris水迷宫实验。于麻醉结束后1、3和7d时(C组于相应时点)处死大鼠后取海马组织,采用ELISA法检测海马cAMP含量,Westernblot法检测海马CREB、磷酸化CREB(p-CREB)及PKA表达,计算p-CREB/CREB比值。结果与C组比较,Sev组麻醉结束后1d时逃避潜伏期和游泳距离延长,原平台穿越次数减少,原平台象限停留时间缩短,麻醉结束后1、3及7d时海马cAMP和PKA表达下调,麻醉结束后1d时CREB和p-CREB表达下调,p-CREB/CREB比值降低(P<0.05)。结论七氟醚诱发老龄大鼠认知功能障碍的机制可能与抑制海马cAMP-PKA-CREB信号通路活性有关。

Objective To evaluate the effect of sevoflurane on hippocampal cyclic AMP (cAMP)-protein kinase A (PKA)-cAMP response element-binding protein (CREB) signaling pathway in aged rats. Methods Sixty healthy aged male Sprague-Dawley rats, aged 18 months, weighing 600-750 g, were divided into control group (C group, n=30) and sevoflurane group (group Sev, n=30) using a random number table method.Group Sev inhaled 2% sevoflurane for 4 h. Group C inhaled the mixture of 50% air and oxygen (2 L/min) for 4 h. Morris water maze test was performed on 1-6 days before anesthesia and at 1 day after the end of anesthesia (at the corresponding time points in group C). The animals were sacrificed and hippocampi were removed at 1, 3 and 7 days after anesthesia (at the corresponding time points in group C) for determination of the hippocampal cAMP content (using enzyme-linked immunosorbent assay) and expression of hippocampal CREB, phosphorylated CREB (p-CREB) and PKA (using Western blot), and the p-CREB/CREB ratio was calculated. Results Compared with group C, the escape latency and swimming distance were significantly prolonged, the frequency of crossing the original platform was decreased, the time of staying at the original platform quadrant was shortened at 1 day after the end of anesthesia, and the expression of hippocampal cAMP and PKA was down-regulated at 1, 3 and 7 days after the end of anesthesia, and the expression of CREB and p-CREB was down-regulated and p-CREB/CREB ratio was decreased at 1 day after the end of anesthesia in group Sev (P<0.05). Conclusion The mechanism of sevoflurane-induced postoperative cognitive dysfunction may be related to inhibiting hippocampal cAMP-PKA-CREB signaling pathway in aged rats.