Department of Psychology, Arizona State University, Box 1104, Tempe, AZ 85287-1104, USA.
Eur J Neurosci. 2011 Sep;34(6):1023-30. doi: 10.1111/j.1460-9568.2011.07820.x. Epub 2011 Sep 2.
Chronic stress results in reversible spatial learning impairments in the Morris water maze that correspond with hippocampal CA3 dendritic retraction in male rats. Whether chronic stress impacts different types of memory domains, and whether these can similarly recover, is unknown. This study assessed the effects of chronic stress with and without a post-stress delay to evaluate learning and memory deficits within two memory domains, reference and working memory, in the radial arm water maze (RAWM). Three groups of 5-month-old male Sprague-Dawley rats were either not stressed [control (CON)], or restrained (6 h/day for 21 days) and then tested on the RAWM either on the next day [stress immediate (STR-IMM)] or following a 21-day delay [stress delay (STR-DEL)]. Although the groups learned the RAWM task similarly, groups differed in their 24-h retention trial assessment. Specifically, the STR-IMM group made more errors within both the spatial reference and working memory domains, and these deficits corresponded with a reduction in apical branch points and length of hippocampal CA3 dendrites. In contrast, the STR-DEL group showed significantly fewer errors in both the reference and working memory domains than the STR-IMM group. Moreover, the STR-DEL group showed better RAWM performance in the reference memory domain than did the CON group, and this corresponded with restored CA3 dendritic complexity, revealing long-term enhancing actions of chronic stress. These results indicate that chronic stress-induced spatial working and reference memory impairments, and CA3 dendritic retraction, are reversible, with chronic stress having lasting effects that can benefit spatial reference memory, but with these lasting beneficial effects being independent of CA3 dendritic complexity.
慢性应激会导致雄性大鼠在 Morris 水迷宫中出现可逆的空间学习障碍，这与海马 CA3 树突回缩有关。目前尚不清楚慢性应激是否会影响不同类型的记忆领域，以及这些记忆领域是否可以类似地恢复。本研究通过评估应激后是否存在延迟来评估两种记忆领域（参考记忆和工作记忆）的学习和记忆缺陷，评估慢性应激对雄性 Sprague-Dawley 大鼠在放射臂水迷宫（RAWM）中的影响。三组 5 月龄雄性 Sprague-Dawley 大鼠分别未进行应激处理（对照组，CON）、束缚应激（每天 6 小时，共 21 天），然后在应激后即刻（STR-IMM）或应激后 21 天延迟（STR-DEL）进行 RAWM 测试。尽管各组在 RAWM 任务中学习情况相似，但在 24 小时保留试验评估中存在差异。具体而言，STR-IMM 组在空间参考和工作记忆领域均出现更多错误，且这些缺陷与海马 CA3 树突分支点和长度减少有关。相比之下，STR-DEL 组在参考和工作记忆领域的错误明显少于 STR-IMM 组。此外，STR-DEL 组在参考记忆领域的 RAWM 表现优于 CON 组，且这与 CA3 树突复杂性的恢复有关，表明慢性应激具有长期增强作用。这些结果表明，慢性应激引起的空间工作记忆和参考记忆损伤以及 CA3 树突回缩是可逆转的，慢性应激具有持久的作用，可以改善空间参考记忆，但这些持久的有益作用与 CA3 树突复杂性无关。
