快速眼动睡眠剥夺对中枢5-羟色胺缺失小鼠orexin阳性神经元活性的影响

为探讨中枢5羟色胺(5-HT)的缺失对正常睡眠和快速眼动睡眠剥夺(REM sleep deprivation)情况下orexin阳性神经元活动的影响,本研究利用中枢5-HT神经元缺失的条件性基因敲除小鼠(Pet1-Cre/Lmx1b flox/flox CKO小鼠),采用小平台水环境法建立小鼠快速眼动睡眠剥夺模型,免疫组化方法观察野生型小鼠和中枢5-HT神经元缺失小鼠在正常睡眠状态及8 h快速眼动睡眠剥夺后下丘脑内orexin阳性神经元的数量,免疫组化双标法观察orexin/c-fos双标神经元占orexin阳性神经元的比例。结果显示:CKO小鼠睡眠剥夺前后orexin阳性神经元的数量未见明显差别,与野生型小鼠相比亦未见统计学差别;在正常睡眠状态下(对照组),CKO小鼠orexin/c-fos双标神经元的数量与野生型小鼠相当,但睡眠剥夺后明显低于野生型小鼠睡眠剥夺组。本研究结果提示,作为维持觉醒的重要神经递质5-HT的缺失可能降低了中枢神经系统的觉醒水平,致使睡眠剥夺不能提高促发和维持觉醒的orexin阳性神经元的活性。

Effect of rapid eye movement sleep deprivation on neural activity of orexin-positive neurons in central serotonin deficient mice

To study the effect of central serotonin deficiency on the activity of orexin-expression neurons under normal sleep and rapid eye movement(REM) sleep deprived conditions,the central serotonin deficient mice(Pet1-Cre/Lmx1b flox/flox CKO mice) and small platform method was used to establish mouse model of REM sleep deprivation.Immunohistochemical method was performed to observe total number of orexin-positive neurons of both wild type and central serotonin deficient mice under normal sleep condition or 8 h REM sleep deprivation.Then double immunostaining was used to detect orexin/c-fos double-labeled cells and the percentage to total orexin-positive neurons was calculated.The results showed that total number of orexin-positive neurons was not changed under both normal sleep and REM sleep deprivation and there were not differences between the two genotypes.However,the percentage of orexin/c-fos double-labeled cells was significantly decreased in CKO mice after REM sleep deprivation compared with wild type littermates.The present results indicate that,the deficiency of serotonin,an important neural transmitter in sleep-wake regulation in central nervous system,may decrease the level of waking and fail to enhance the neural activity of orexin-expressing neurons after REM sleep deprivation.