丙泊酚麻醉对新生期大鼠海马BDNF及Trk-B的影响

目的观察新生期大鼠丙泊酚麻醉对空间学习记忆能力发育的影响。方法 7日龄SD大鼠45只,随机平均分为3组:空白对照组,不做任何处理;丙泊酚麻醉组,腹腔注射丙泊酚25 mg.kg-1,每20 min给予首次剂量的1/2,麻醉维持2 h;中长链脂肪乳注射组,腹腔注射脂肪乳25 mg.kg-1,每隔20 min给予首次剂量的1/2。待麻醉后4 h,每组随机处死6只,免疫组化法分析海马的caspase-3表达,蛋白免疫印迹法测定BDNF和Trk-B的水平。其余同窝饲养至40 d时行Morris水迷宫测定。结果与对照组比较,丙泊酚麻醉组海马BDNF及Trk-B表达明显减少、caspase-3表达明显增加(P<0.05),脂肪乳组与对照组差异无显著性。Morris水迷宫实验中,丙泊酚组大鼠寻找隐藏平台潜伏期较对照组明显延长(P<0.05),在记忆保留实验中丙泊酚组大鼠穿越平台次数明显少于对照组(P<0.05),脂肪乳组与对照组均无明显差异。结论新生期大鼠丙泊酚麻醉可影响空间认知功能发育,该效应可能与新生期海马内神经元凋亡增加,BDNF途径抑制有关。

Effects of propofol anesthesia on the expression of BDNF and Trk-B in hippocampus in neonatal rats

Aim To observe the effects of propofol anesthesia on the spatial learning and memory function in neonatal rats.Methods Forty-five seven-day-old SD rats were randomly divided into three groups as followings:the control group in which rats were not treated,the propofol anesthesia group in which rats were administered intraperitoneally with propofol(25 mg·kg-1) initially then maintained with the half dosage every 20 min for 2 h,and the long chain fat emulsion group in which rats were treated with emulsion using the same regiment as propofol group.Four hours after treatment,six rats in each group were randomly executed and hippocampus were harvested to assay for the expression of Caspase-3 by immunohistochemistry and the level of BDNF and Trk-B by Western blot.The rest were bred to forty days old,then the ability of spatial learning and memory was measured by Morris water maze.Results Compared with the control group,the levels of BDNF and Trk-B decreased significantly.In contrast,the expression of Caspase-3 increased markedly in the propofol group(P<0.05).There was no significant difference between the control group and the emulsion group.The Morris water maze test showed a significantly longer escape latency in the propofol group than in the control group(P<0.05).Compared with the control group,the propofol group exhibited a lower frequency of passing through the platform(P<0.05).There was also no significant difference between the control group and the emulsion group.Conclusion Propofol anesthesia in neonatal rats can interfere with the development of the spatial cognitive function,which may result from the enhanced apoptosis of neurons and the inhibited activity of BDNF pathway in hippocampus during neonatal period.