抑制SIK1易化蓝光牵引重置SCN生物钟逆转吸入全麻药致小鼠昼夜节律紊乱研究

The normal circadian rhythm is critical for the normal physiological functions of all organs in the body. General anesthesia is required for 75% of the 300 million surgical patients worldwide each year, for which inhalational anesthetics are the most convenient and widely used. Our previous study confirmed that inhalational anesthetics can cause severe circadian disorders, manifested as changes of motor activity and loss of melatonin circadian rhythm. The "central pacemaker” of circadian clock in mammalian located in the suprachiasmatic nucleus (SCN). Inhalational anesthetics can cause phase shifting and decreasing of clock gene expression in SCN. The mechanism may be related to perturbation of transcription onset of mPer gene and changes in phosphorylation level of GSK3β and AMPK that involved in the regulation of clock gene. This study aims to reset circadian clock in SCN by the use of naturally existed light entrainment phenomenon especially with short wavelength blue light. Blue light preconditioning or postconditioning will be given to mice before or after anesthesia. Meanwhile we design to inhibit the light entrainment limitation enzyme SIK1, to facilitate light entrained circadian clock reset under normal illumination level (800lux), so as to reverse or against inhalational anesthetics induced SCN circadian disorder in mice, and to restore the normal circadian rhythm after anesthesia. We will also explore the key molecular mechanisms that mediate reversing effects of blue light preconditioning or postconditioning in combination with SIK1 inhibitor, so as to develop innovative strategies for prevention and treatment of circadian disorder and the related adverse reactions following use of inhalational anesthetics in clinical setting.

正常昼夜节律对全身各器官系统正常功能至关重要。全球每年3亿手术患者中75%需要全身麻醉，吸入性全麻药使用方便且广泛。我们前期研究证实吸入性全麻药可引起小鼠昼夜节律严重紊乱，表现为活动能力变化，褪黑素昼夜节律消失。哺乳动物生物钟“中枢起搏点”位于视交叉上核。吸入性全麻药可引起钟基因相位偏移/表达量降低，机制可能与吸入性全麻药影响mPer基因转录启动过程或改变钟基因调控相关蛋白激酶GSK3β和AMPK磷酸化水平有关。本研究利用短波长光能有效牵引视交叉上核生物钟重置的天然现象，在小鼠麻醉前或苏醒后启动蓝色光照（480nm）前处理或后处理，同时抑制光牵引自限性关键酶SIK1，易化日常照度条件（800lux）光牵引效果，以期逆转或对抗吸入麻醉药诱发的小鼠视交叉上核生物钟紊乱，恢复全麻后正常昼夜节律。并探索光牵引逆转效果的关键分子机制，为临床防治吸入性全麻药诱发昼夜节律紊乱及其相关不良反应提供策略。

全身麻醉可被定义为一种遗忘、镇静、制动、镇痛以及意识消失等可逆性的药理学状态。全麻药物是如何导致意识消失以及又是如何从全麻中恢复意识的具体机制至今仍是自然科学未解之谜。既往研究发现全身麻醉与睡眠-觉醒有部分共同的神经环路机制，调控调节睡眠-觉醒的某些特定核团或者神经递质，可影响全麻的全身作用。下丘脑视交叉上核SCN是哺乳动物主要的中枢神经系统昼夜节律起搏点，调控睡眠-觉醒等生物节律。研究证实SCN向下丘脑背内侧核DMH有密集的投射，DMH将抑制性的γ-氨基丁酸能神经纤维投射到腹外侧视前核VLPO，将兴奋性的谷氨酸能神经纤维投射到外侧下丘LH。此外，SCN也可通过DMH投射到蓝斑核LC，从而兴奋睡眠-觉醒网络中的促觉醒神经元以及大脑皮层发挥促觉醒作用。动物研究和临床研究均表明蓝光可以促进觉醒。但单色蓝光对麻醉的影响如何，目前还不清楚。本研究发现：460nm的单色蓝光可以促进七氟烷麻醉苏醒而不影响麻醉诱导；单色蓝光可以减少2.5%七氟烷麻醉时爆发抑制的产生；单色蓝光通过激活SCN及SCN下游促觉醒核团LH和PFC在七氟烷麻醉中发挥减浅麻醉和促觉醒作用。本研究为利用自然的环境因素促进全身麻醉苏醒和处理全身麻醉苏醒延迟提供了新的思路。