摘要目的 评价海马磷脂酰肌醇3-激酶∕蛋白质丝氨酸苏氨酸激酶(PI3K∕Akt)信号通路在外源性食欲素A改善异氟醚致小鼠记忆功能减退中的作用.方法 清洁级健康成年雄性C57BL∕6小鼠100只,体重20～25 g,侧脑室置管成功后,采用随机数字表法分为5组(n=20):对照组(C组)和异氟醚组(I组)给予生理盐水,食欲素A组(OA组)给予1.5 mmol∕L食欲素A,食欲素A+二甲基亚砜组(OA+D组)给予1.5 mmol∕L食欲素A(溶于二甲基亚砜),食欲素A+PI3K抑制剂LY294002组(OA+LY组)给予1.5 mmol∕L食欲素A+10 mmol∕L LY294002.除C组仅吸入纯氧2 h(氧流量2 L∕min)外,其余各组小鼠均吸入1.4％异氟醚2 h,并于麻醉结束前15 min依上述浓度侧脑室注射相应药物2μl.每组随机取12只小鼠于麻醉结束后2 h时行条件恐惧刺激实验,并于24 h后进行记忆提取.各组剩余8只小鼠于麻醉结束后2 h时处死取海马组织,采用Western blot法检测PI3K、Akt、磷酸化Akt(p-Akt)的表达.结果 与C组比较,I组小鼠恐惧箱内僵直时间缩短,PI3K、Akt和p-Akt表达下调,p-Akt∕Akt比值降低(P<0.05);与I组比较,OA组小鼠恐惧箱内僵直时间延长,PI3K和p-Akt表达上调,p-Akt∕Akt比值升高(P<0.05);OA组和OA+D组各指标比较差异无统计学意义(P>0.05);与OA+D组比较,OA+LY组小鼠恐惧箱内僵直时间缩短,PI3K、Akt、p-Akt表达下调,p-Akt∕Akt比值降低(P<0.05).结论 海马PI3K∕Akt信号通路参与了外源性食欲素A改善异氟醚致小鼠记忆功能减退的过程.

abstractsObjective To evaluate the role of hippocampal phosphatidylinositol 3-kinase∕serine-threonine kinase (PI3K∕Akt) signaling pathway in exogenous orexin A-induced improvement of isoflurane anesthesia-caused decline in memory function of mice. Methods A total of 100 pathogen-free healthy adult male C57BL∕6 mice, aged 8-12 weeks, weighing 20-25 g, in which the lateral ventricle was catheter-ized, were divided into 5 groups (n = 20 each) using a random number table: control group (group C), isoflurane group (group I), orexin A group (group OA), orexin A plus dimethyl sulfoxide group (group OA+D) and orexin A plus PI3K inhibitor LY294002 group (group OA+LY). Normal saline was administra-ted in group C and group I. Orexin A 1. 5 mmol∕L was given in group OA. Orexin A 1. 5 mmol∕L (dissolved in dimethyl sulfoxide) was given in group OA+D. Orexin A 1. 5 mmol∕L and LY29400210 mmol∕L were given in group OA+LY. Group C only inhaled pure oxygen for 2 h (oxygen flow rate 2 L∕min), all the rest groups inhaled 1. 4％ isoflurane for 2 h, and the corresponding drug 2 μl was injected into the lateral cere-bral ventricle according to the concentration mentioned above at 15 min before the end of anesthesia. Twelve mice were randomly selected from each group and trained for contextual fear conditioning test, and then fear memory retrieval was conducted at 24 h after training. The rest 8 mice in each group were sacrificed at 2 h after the end of anesthesia and their brains were removed for determination of the expression of PI3K, Akt and phosphor-Akt (p-Akt) protein by Western blot. Results Compared with group C, the freezing time was significantly shortened, the expression of PI3K, Akt and p-Akt was down-regulated, and p-Akt∕Akt ratio was decreased in group I (P<0. 05). Compared with group I, the freezing time was significantly pro-longed, the expression of PI3K, Akt and p-Akt was up-regulated, and p-Akt∕Akt ratio was increased in group OA (P<0. 05). There was no significant difference in each parameter mentioned above between group OA and group OA+D (P>0. 05). Compared with group OA+D, the freezing time was significantly short-ened, the expression of PI3K, Akt and p-Akt was down-regulated, and p-Akt∕Akt ratio was decreased in group OA+LY (P<0. 05). Conclusion Hippocampal PI3K∕Akt signaling pathway is involved in exoge-nous orexin A-induced improvement of isoflurane anesthesia-caused decline in memory function of mice.