Shinohara Keisuke, Hata Toshimichi
Faculty of Psychology, Doshisha University, Kyotanabe, Japan.
Faculty of Psychology, Doshisha University, Kyotanabe, Japan.
Behav Brain Res. 2014 Feb 1;259:261-7. doi: 10.1016/j.bbr.2013.11.016. Epub 2013 Nov 17.
Several studies have demonstrated that the hippocampal N-methyl-D-aspartate type glutamate receptors (NMDARs) are necessary for the acquisition but not the retention of spatial reference memory. In contrast, a few studies have shown that post-acquisition repetitive intraperitoneal injections of an NMDAR antagonist facilitate the retention of spatial reference memory in a radial maze task. In the present study, we investigated the role of hippocampal NMDARs in the retention of spatial reference memories in Morris water maze. In Experiment 1, 24 h after training (4 trials/day for 4 days), D-AP5 was chronically infused into the hippocampus of rats for 5 days. In the subsequent probe test (seven days after training), we found that rats infused with D-AP5 spent a significantly longer time in the target quadrant compared to chance level, whereas rats in the control group did not. In Experiment 2, D-AP5 was infused into the hippocampus 1 (immediate) or 7 (delayed) days after the training session. In the probe test, following the retention interval of 13 days, immediate infusion facilitated the performance in a manner similar to Experiment 1, whereas the delayed infusion did not. These findings suggest that hippocampal NMDARs play an important role in the deterioration of spatial reference memory.
多项研究表明，海马体中的N-甲基-D-天冬氨酸型谷氨酸受体（NMDARs）对于空间参考记忆的获取是必需的，但对于其保持并非必需。相比之下，一些研究表明，在获取记忆后腹腔内重复注射NMDAR拮抗剂可促进大鼠在放射状迷宫任务中对空间参考记忆的保持。在本研究中，我们调查了海马体NMDARs在莫里斯水迷宫中空间参考记忆保持中的作用。在实验1中，训练后24小时（每天4次试验，共4天），将D-AP5长期注入大鼠海马体，持续5天。在随后的探针试验（训练后7天）中，我们发现注入D-AP5的大鼠在目标象限停留的时间明显长于随机水平，而对照组大鼠则没有。在实验2中，在训练后1天（即时）或7天（延迟）将D-AP5注入海马体。在探针试验中，经过13天的保持期后，即时注入的效果与实验1相似，促进了大鼠的表现，而延迟注入则没有。这些发现表明，海马体NMDARs在空间参考记忆的衰退中起重要作用。
