不同训练方式建立大鼠空间记忆后海马结构NMDA受体表达的变化

Changes of NMDA receptor expression in rat hippocampal formation after establishment of spatial memory by different training modes

短期强化训练能否建立可靠的空间长时记忆?用不同训练方式建立空间记忆后,大鼠海马结构NMDA受体的表达发生怎样的变化?目前尚未见明确报道。本研究应用Morris水迷宫方法分别采用以下模式对大鼠进行训练:空间长时记忆训练模式(LT组)、空间短时记忆训练模式(ST组)以及短期强化训练模式(SRT组),对不同训练模式建立的空间记忆进行了比较,应用免疫荧光组织化学方法检测各组大鼠海马结构NMDA/NR1受体表达的变化。结果表明,Morris水迷宫训练过程中,LT和SRT组大鼠寻找站台的平均潜伏期和策略均无显著性差异;记忆检测发现,除LT组大鼠在站台所在象限的停留时间明显长于SRT组大鼠外,两组大鼠寻找站台的潜伏期和策略以及穿越站台的次数均无显著性差异。ST组大鼠海马结构NMDA/NR1的免疫反应强度与对照组相比,无显著差异。但是,LT和SRT组大鼠海马CA1区锥体细胞层及齿状回的颗粒细胞层NMDA/NR1免疫荧光反应都明显增强,两组之间比较无显著差异,但是两组分别与对照组和ST组相比均有显著性差异。上述结果提示,短期强化训练可建立与长期训练基本相同的空间长时记忆。大鼠海马结构CA1区和齿状回NMDA受体表达的增加,可能是空间长时记忆形成的机制之一。

There is no unambiguous report so far on whether short reinforcing training could establish stable spatial long-term memory and how the NMDA/NR 1 expression in the hippocampal formation changes after establishment of short- and long-term memory, In the present study, three spatial memory training modes of Morris water maze were used： spatial long-term memory training mode （LT group）, spatial short-term memory training mode （ST group） and short reinforcing training mode （SRT group）. The characteristics of those memories established by different training modes were compared, The immunofluorescence histochemical staining technique was used to observe the changes of NMDA/NR1 expression in the hippocampal formation in the three groups, The results showed that, during Morris water maze training, no significant difference was found in the mean latency and the strategies to the target between the LT and SRT groups. The examination of the memories following different trainings indicated that the mean latency and the strategies to the target as well as the times crossing the target in LT group were not significantly different from those in SRT group, except that the mean time remaining in the platform quadrant in LT group was significantly longer than that in SRT group. In addition, no significant difference in the intensity of NMDA/NR 1 immunoreactivity in CA 1, CA3 and dentate gyrus of the hippocampal formation was observed between the control and ST groups or between LT and SRT groups. However, the intensity of NMDA/NRI immunoreactivity in CA1 area and dentate gyrus in both LT and SRT groups was significantly increased as compared with that in ST or the control groups. These results suggest that the short reinforcing training mode can establish long-term spatial memory, which is almost the same as that established by the long-term training mode, and that the increase of NMDA/NRI expression in CAI area and dentate gyrus of the hippocampal formation may be one of the mechanisms of spatial long-term memory formation.