“睡眠-觉醒”节律偏移在NR2B介导的老年POCD中的作用

Postoperative cognitive dysfunction (POCD) exhibits the impaired learning and memory as the major performance and age is one of the most important risk factors. Based on our previous studies and other research findings, we suggest that the sleep-wake rhythm could shift under general anesthesia, furthermore, the aging-induced amplitude reduction of central circadian pacemaker and the decreased secretion of melatonin may delay the reset of sleep-wake rhythm. The phase-shifting sleep-wake rhythm may affect the rhythmic expression of NR2B and finally change learning and memory via its downstream molecules AMPAR and CREB. Long-time phase-shifting sleep-wake rhythm after general anesthesia could finally result in POCD. In this study, we will subcutaneously implant the Mini Mitter and the microchip of Intellicage into mice and perform the laparotomy under general anesthesia. Daylight changes, noise isolation, melatonin intervention and agonistic or antagonistic NR2B/AMPAR/CREB will be used to detect changes of sleep-wake rhythm and cognitive function under different treatments in different ages. Behavioral and molecular biology techniques will be uesd to explore the role of NR2B-AMPAR/CREB in the crosstalk between long-time phase-shifting sleep-wake rhythm and POCD among the aged. This study will provide new ideas for the prevention and treatment of POCD.

术后认知功能障碍(POCD)以学习和记忆功能受损为重要表现，年龄是其重要危险因素。我们的前期研究和现有文献提示，"睡眠-觉醒"节律可在全麻药物的作用下发生偏移，年老导致的中枢昼夜起搏器振幅减少，褪黑素分泌下降等，可使"睡眠-觉醒"节律恢复延迟。偏移的睡眠节律可影响NR2B的节律性表达，从而通过影响其下游AMPAR和CREB的表达导致学习和记忆的改变。全麻后"睡眠-觉醒"节律长时期偏移可最终形成POCD。本研究将在小鼠皮下植入Mini Mitter及智能鼠笼检测芯片，于全麻下行普通开腹术，采用光照变化、噪音隔离、褪黑素干预及NR2B、AMPAR、CREB激动/拮抗等方法，检测不同年龄及处理下"睡眠-觉醒"节律及认知功能改变，采用行为学、分子生物学等技术，探讨NR2B-AMPAR/CREB在"睡眠-觉醒"节律长时期偏移与老年POCD之间的机制联系，为临床防治POCD提供新的思路。

术后认知功能障碍(POCD)以学习和记忆功能受损为重要表现，年龄是其重要危险因素。我们的前期研究和现有文献提示，“睡眠-觉醒”节律可在全麻药物的作用下发生偏移，年老导致的中枢昼夜起搏器振幅减少，褪黑素分泌下降等，可使“睡眠-觉醒”节律恢复延迟。在动物和临床试验中均提示在昼夜节律紊乱的状态下，学习和记忆力明显下降，而改善昼夜节律可缓解甚至逆转认知损害，所以昼夜节律对学习与记忆至关重要。节律的中枢控制器位于下丘脑视交叉上核(Suprachiasmatic Nucleus, SCN）。研究普遍认为，由Bmal1-Clock和Per-Cry复合体所介导的钟基因转录-翻译反馈调节环路可为昼夜节律转换提供重要分子基础。本项目深入探讨了长时程异氟醚麻醉后昼夜节律的改变与认知功能下降间的机制关联。首先建立了6小时长时程小鼠活动期1.3%异氟醚麻醉POCD模型；通过腹腔内植入Mini Mitter，智能鼠笼、水迷宫，条件恐惧实验，新物体识别等检测手段明确POCD小鼠昼夜、体温昼夜节律振幅、相位、中值等参数和空间记忆、情景记忆、新物体识别等记忆功能的改变；使用RT-PCR检测，Chronos-Fit程序拟合POCD小鼠中枢和外周的Bmal1、Clock、Cry1、Per2生物钟基因的余弦函数，明确节律性改变；通过在麻醉前1周对小鼠行褪黑素灌胃预处理、麻醉前3天调整小鼠光照方案为24hr完全黑暗或24hr持续光照、麻醉前1-2周干预小鼠饮食时间来调制昼夜节律，明确认知功能改变；通过中枢和外周给予NR2B、5-HT7R拮抗剂、激动剂，探讨NR2B和5-HT7R在异氟醚麻醉后昼夜节律和认知功能改变中的机制关联。