母婴早期分离对成年大鼠学习记忆的影响及其神经生物学机制实验研究

Experimental study of the effects and neurobiological mechanisms of early maternal separation on the learning and memory in rats

目的：观察母婴早期分离对成年大鼠学习记忆的影响，并探讨其可能的神经生物学机制。方法将出生后7 d的仔鼠24只随机分为3组，即正常对照组、母婴部分分离组和母婴完全分离组，各8只。大鼠出生后81～84 d，用Morris水迷宫观察母婴分离对成年大鼠学习记忆的影响，以尼氏染色显示海马CA1区神经元的损伤情况，并检测海马丙二醛（MDA）和超氧化物歧化酶（SOD）的含量。结果母婴部分分离组大鼠逃避潜伏期（EL）比正常对照组延长（P＜0．05），海马CA1区神经元轻度丢失，穿越平台次数、平台象限游泳时间、海马MDA和SOD含量与正常对照组比较差异无统计学意义（ P＞0．05）；母婴完全分离组大鼠EL较正常对照组延长（P＜0．05），穿越平台次数和平台象限的游泳时间比正常对照组和母婴部分分离组均减少（P＜0．05），海马CA1区神经元损伤较母婴部分分离组加重，MDA含量比正常对照组升高（P＜0．05），SOD活性较正常对照组和母婴部分分离组均降低（P＜0．05）。结论母婴早期分离程度越深，大鼠成年期学习记忆能力降低明显，这可能是大鼠脑内氧自由基过度堆积导致海马CA1区神经元损伤所致。

Objective To observe the effects of early maternal separation on the learning and memory in rats and investigate the possible neurobiological mechanisms .Methods 24 neonatal rats 7 days after birth were randomly divided into normal control group ,partial maternal separation group （ PMS） and complete maternal separation group （ CMS） ,8 rats in each group .The effect of early maternal separation on the learning and memory in rats at 81 to 84 days after birth was observed by Morris water maze ,the damage of neurons in hippocampus CA 1 area was detected by Nissl staining,and the content of malondialdehyde （ MDA） and superoxide dismutase （ SOD） in hippocampus were detected.Results The escape latent period of PMS rats was longer than that in normal control group （P〈0.05）. There were no statistical significance between PMS group and normal control group on times of crossing platform , swimming time in the platform quadrant and contents of MDA and SOD in hippocampus （P〉0.05）.There was nean-on mild loss in the hippocampus CA 1 area.The escape latent period in CMS group was longer than that in normal con-trol group （P〈0.05）,the times of crossing platform and the swimming time in the platform area were reduced as compared with those in normal control group and PMS group （P〈0.05）,the damage of neurons in CA1 area was ag-gravated as compared with that in PMS group , the content of MDA was higher than that in normal control group （ P〈0.05） ,the activity of SOD was decreased as compared with that in normal control group and PMS group （P〈0.05）.Conclusion The deeper early ma-ternal separation ,the more learning and memory reduc-ing in adult rats,which may be result from the neuron damage of the hippocampus CA 1 area caused by exces-sive accumulation of oxygen free radical in rat brain .