新生期重复吸入七氟醚的大鼠幼年期学习记忆功能与海马体积变化

Effects of neonatal repeated inhalation of sevoflurane on ability of learning and memory and hippocampal volume in infantile rats

目的近期大量研究表明七氟醚麻醉可能引起学习记忆功能障碍。文中拟通过Morris水迷宫检测学习记忆能力及MRI测量海马体积,探索新生期间断重复吸入2.6%七氟醚后的大鼠幼年期海马体积与学习记忆能力变化。方法新生SD大鼠32只,随机数字表法分为实验组和对照组,各16只,出生后第7、14、21天分别吸入2.6%七氟醚、1 L/min O2+1 L/min Air;均于第31-37天行Morris水迷宫实验以检测学习记忆能力;第37天在1%戊巴比妥钠腹腔注射麻醉后行MRI颅脑扫描,测量颅脑容积及双侧海马体积。结果 1定位航行实验中,2组大鼠第32-35天逃避潜伏期差异无统计学意义(P>0.05);空间探索实验中,实验组较对照组平台象限滞留时间、平台象限运动距离、平台区域进入次数差异均无统计学意义(P>0.05)。2实验组较对照组颅脑容积差异无统计学意义[(1.53±0.18)cm3vs(1.60±0.13)cm3,P>0.05];右侧海马体积差异无统计学意义[(16.15±1.76)mm3vs(16.46±1.71)mm3,P>0.05]、左侧海马体积减小[(16.46±1.71)mm3)vs(18.10±2.53)mm3,P<0.05]。结论新生期间断重复吸入七氟醚后对大鼠幼年期学习记忆能力影响不大,MRI测量海马体积尚不足以用来诊断认知功能障碍。

Objective A large number of recent studies show that sevoflurane anesthesia may cause learning and memory dysfunction. The aim of this study was to explore changes of learning and memory ability and hippocampal volume in infantile rats after neonatal interrupted and repeated inhalation of 2. 6% sevoflurane through detecting the learning and memory ability by Morris water maze and the hippocampus volume by MRI. Methods Thirty two neonatal SD rats were randomly devided into two groups（ n = 16） ：experimental group and control group. Rats inhalated 2. 6% sevoflurane in the experimental group and 1 L / min O2＋ 1 L / min Air in the control group at the postnatal days of 7,14 and 21（ P7,P14,P21）.The learning and memory ability was determined by the Morris water maze test from P31 to P37; The brains of rats were scanned by magnetic resonance imaging（ MRI） machine under anesthesia with 1%sodium pentobarbital at P37,and the brain and bilateral hippocampal volumes were measured. Results 1 In the place navigation test,the escape latency had no significant difference between the two groups（ P﹤0. 05）. In the spatial probe test,the dwelling time,movement distance and number of entering times in platform quadrant decreased slightly in experimental group compared with those in the control group,while there was no significant difference（ P﹤0. 05）. 2The brain volume [（ 1. 53 ± 0. 18） cm3vs（ 1. 60 ± 0. 13）cm3]and right hippocampal volume [（ 16. 15 ± 1. 76） mm3vs（ 16. 46 ± 1. 71） mm3] had no significant difference between the two groups（ P﹤0. 05）. The left hippocampal volume [（ 16. 46 ± 1. 71） mm3]was decreased in the experimental group compared with the control group [（ 18. 10 ± 2. 53） mm3]（ P﹤0. 05）. Conclusion The learning and memory ability has no significant changes in infantile rats after neonatal interrupted and repeated sevoflurane inhalation and MRI examination of hippocampal volume is not sufficient for the diagnosis of cognitive dysfunction.