Ramsar Campus, Mazandaran University of Medical Sciences, Ramsar, Iran.
Department of Physiology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran; Immunogenetics Research Center, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
Life Sci. 2021 Jan 15;265:118777. doi: 10.1016/j.lfs.2020.118777. Epub 2020 Nov 18.
The dorsal raphe nucleus (DRN) is a brainstem nucleus involved in the pathophysiology of the depression, through its serotoninergic innervation. Furthermore, depressive symptoms in patients are also associated with some memory and sleep complaints. Anatomical evidence confirmed the presence of projections from the lateral hypothalamus to serotonergic neurons of the dorsal raphe nucleus (DRN). These projection fibers release orexin neuropeptides which play roles in the spatial memory. Both of the orexinergic receptors are widely distributed in dorsal raphe nucleus. Therefore, the present work was aimed to assess the probable roles of orexin 1 and 2 receptors using an orexin 1 receptor antagonist, SB-334867-A, and an orexin 2 receptor antagonist, TCS-OX2-29 in the DRN on the retrieval, and consolidation phases of spatial reference memory in the Morris water maze (MWM) task. The results demonstrated that blocking orexin 1 receptors in the DRN impairs the process of memory consolidation in the spatial MWM via increasing in the time of the escape latency of the probe day. Blocking these receptors did not affect the retrieval phase of MWM learning. Furthermore, blocking of the orexin 2 receptors in this area did not affect neither consolidation nor retrieval phases of the memory. In conclusion, orexin 1 receptors in the DRN play major roles in the consolidation of the spatial reference memory in rats.
中缝背核（DRN）是与抑郁症病理生理学相关的脑干核团，通过其 5-羟色胺能神经支配。此外，患者的抑郁症状也与一些记忆和睡眠问题有关。解剖学证据证实了外侧下丘脑投射到中缝背核（DRN）5-羟色胺能神经元的存在。这些投射纤维释放食欲素神经肽，在空间记忆中发挥作用。两种食欲素受体广泛分布于中缝背核。因此，本工作旨在使用食欲素 1 受体拮抗剂 SB-334867-A 和食欲素 2 受体拮抗剂 TCS-OX2-29 评估中缝背核中食欲素 1 和 2 受体的可能作用，对空间参考记忆的检索和巩固阶段在 Morris 水迷宫（MWM）任务中。结果表明，DRN 中阻断食欲素 1 受体通过增加探测日逃逸潜伏期时间，损害空间 MWM 中记忆巩固过程。阻断这些受体不影响 MWM 学习的检索阶段。此外，阻断该区域的食欲素 2 受体既不影响记忆的巩固阶段，也不影响检索阶段。总之，DRN 中的食欲素 1 受体在大鼠空间参考记忆的巩固中起主要作用。
