Effect Of Rapid Eye Movement Sleep On Neural Activity Of Orexin Neurons In Central Serotonin Deficient Mice

To study the effect of central serotonin deficiency on Orexin neuronal activity under normal sleep and rapid eye movement (REM) sleep deprived conditions. Small platform method was used to establish mouse model of REM sleep deprivation. Immunohistochemistry method was performed to observe total number of Orexin positive neurons of both wild type and central serotonin deficient mice (Pet1-Cre/Lmx1b flox/flox CKO mice) under normal sleep condition or 8 h REM sleep deprivation. Then double immunostaining was used to detect Orexin/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 was not different between the two genotypes. However, the percentage of Orexin/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.