丙泊酚/异氟醚麻醉对大鼠获取空间记忆能力的损害及c-Fos和EGR-1蛋白的变化

目的 通过研究丙泊酚和异氟醚麻醉对青、老年大鼠Morris水迷宫训练成绩及海马CA1区脑神经元FOS核蛋白(c-Fos)和EGR-1核蛋白表达的变化,探讨麻醉后脑神经元分子水平变化与行为学表现的相关性.方法 雄件SD大鼠3月龄(青年组)和20月龄(老年组)各60只,随机分为对照组(不麻醉)、训练组(不麻醉,行Morris水迷宫训练)、丙泊酚组(丙泊酚100 mg·kg-1·h-1,ip;分别于麻醉2 h/4 h后的2 d/2周行Morris水迷宫训练:P2d,P4d,P2W,P4W)、异氟醚组(异氟醚1.2%;分别于麻醉2 h/4 h后的2 d/2周行Morris水迷宫训练:I2d,I4d,I2W,I4W).Morris水迷宫实验连续进行5 d,每天2次,记录逃避潜伏期变化,用以测试各组大鼠的空间学习记忆能力.行为学实验后立即分离海马组织CA1区,应用免疫组化法和酶标法半定量检测c-Fos和EGR-1核蛋白的阳性表达.结果 4 h异氟醚麻醉后,大鼠的认知功能损害均可持续至麻醉后2周,尤以老年大鼠常见且程度严重,表现为学习速度和记忆质量均有所下降(P<0.05),青年组大鼠学习速度略有下降(P<0.05);4 h丙泊酚麻醉后,老年组大鼠认知功能改变可持续至麻醉后2周,但与异氟醚麻醉相比程度较轻,主要表现为学习速度减慢(P<0.05).免疫组化法和酶标法检测结果:与对照组相比,Morris水迷宫训练后,大鼠海马CA1区c-Fos和EGR-1的表达均明显增加(P<0.05);I4d,I4W组老年大鼠和P4d组青年大鼠c-Fos阳性细胞率与单纯训练组大鼠相比有所下降(P<0.05);I4d组老年大鼠EGR-1阳性细胞率与单纯训练组大鼠相比有所下降(P<0.05).结论 麻醉可能会引起大鼠行为学改变,可持续至麻醉后2 d至2周;随着麻醉时程的延长和年龄的增加,改变更为明显,且异氟醚作用较丙泊酚显著.麻醉对大鼠海马CA1区c-Fos和EGR-1表达的影响可能是导致大鼠行为学改变的机制.

Impairment of congnitive function in rats by propofol or isotlurane anesthesia and differential expression of c-Fos and E-GR-1

Objective To investigate the changes in rat cognitive function and c-Fos, EGR-1 expression in rat hippocampus CAI after propofol or isoflurane anesthesia in rats. Methods Sixty 3-month-young rats and sixty 20-month-old rats were ramdomly divided into 4 groups respectively: the control group, the Morris Water Maze (MWM) group, the propofol anesthetized group(rats anesthetized by propofol for 2 h or 4 h, then performed MWM test to assess the cognitive function 2 day or 2 weeks later: P2d, P4d, P2W, P4W), and the isoflurane group (rats inhaled 1.2% anesthetized for 2 h or 4 h0 then performed MWM test to assess the cognitive function 2 day or 2 weeks later: I2d, I4d, I2W, I4W). Rats were killed immediately after the test, and the hippocampus were isolated for determination of c-Fos and EGR-1 using immumo-histochemical and non-radiocative protein kinase assay technique. Results Four hour's isoflurane anesthesia could induce cognitive decline in rats of both age(P< 0.05). The impairment of spatial memory existed at least 2 weeks after anesthesia, and was more serious in old rats than in young rats(P< 0.05); 4 hours propofol anesthesia decreased cognitive function only in old rats(P< 0.05), with less impairment compared to isoflurane anesthesia (P< 0.05). The result of immu-mohistochemical showed that the expression of c-Fos and EGR-1 in MWM group was significantly higher than that of the control group (P< 0.05) ; c-Fos expression in I4d, I4W group of old rats, P4d group of young rats and EGR-I expression in I4d group of old rats were decreased compared with that in MWM group (P< 0.05). Conclusion Impairment of rat cognitive function by propofol or isoflurane lasted for 2 weeks post anesthesia, which was more serious in isoflurane group and exhibited positive correlation with age and anesthesia duration. Inhibition of c-Fos and EGR-1 expression post anesthesia might play an important role in postoperative cog-nitive dysfunction.