A Study Of Sleep Deprivation Models Based On Mouse Behavior And Detection Of BDNF Expression Levels

Sleep loss is an endemic phenomenon in modern society since available sleep time unable to meet physical needs owing to the increasing pressure and quickening pace of work or life.It is always associated with circadian rhythm of sleep-wake disorders.Long-term sleep loss would not only lead to poor sleep quality,but also threaten physical and mental health and cause endocrine disorder,decreased immunity,lack of concentration and soon.Sleep loss has a primary effect on cognition and emotion,mainly including learning and memory and anxiety disorders.Experimental procedures of sleep deprivation(SD)in animal models have been widely employed to unveil various aspects of sleep function as well as to study the effects of sleep loss on behavioral,physiological,cellular and molecular aspects.The ideal animal model is scientific and closed to real human life phenomenon,thus the phenomenon and law is more suitable for human studies.The commonly used SD methods(platform-over-water technique,gentle handing,moving treadmills or rotating wheel,etc.)are wide and varied,but they can’t effectively simulate human sleep loss.However,there are some significant physiological stress factors that affect the effects of sleep deprivation on animals.A new moderate mechanical technique of SD has been used in several studies and it employs intermittent tactile stimulation of freely behaving mice in a standard mouse laboratory cage,using a near-silent motorized mechanical device.In the process,mice just need to step across the shaft to avoid to be pushed to achieve the purpose of gentle deprivation of the whole sleep.To investigate if the new method has more advantages than other methods has important practical value for selecting a relative ideal SD method to do further research on the behavioral change after different duration.Molecular mechanism of learning and memory impairment induced by sleep deprivation is not clear.When sleep loss becomes a chronic condition,hippocampal plasticity and function will be compromised.The molecular mechanism is very complex,and BDNF and CB1 may play roles in it.It is reported that BDNF mediates the processes of learning and memory;After SD BDNF expression level would change;CB1 receptor not only participates in sleep stability regulation but also in learning and memory regulation;Activation of the CB1 receptor could promote the BDNF activity and this process plays an important role in neuroprotection and synaptic transmission.However,it has not been reported whether BDNF and eCB system jointly participate in the spatial learning and memory impairment induced by SD.Therefore,in this study we compared the behavior performance(anxiety-like behavior,learning and memory)induced by the usual SD method,multiple platforms-over-water technique and a new moderate mechanical technique of SD firstly and then their advantages and defects were compared to provide the reference for further long-term SD research.Long-term SD research included the behavior performance and the preliminary mechanism of the spatial learning and memory injury induced by SD.Then we verified the reliability of the model based on both behavior and molecular level Results are as following:(1)After 12 h/24 h SD,mice showed no differences from control mice in the test of anxiety-like behavior and the spatial learning and memory under the two SD methods.48 h SD resulted in that mice showed anxiety-like behavior and the learning performance of 4-8 trials was significantly poorer than the control group when the multiple platforms-over-water technique was used;However,it had no influence on anxiety-like behavior and the spatial learning and memory when the new moderate mechanical technique of SD was used(2)All mice subjected to chronic SD(1w/2w/3w SD)with the new moderate mechanical technique showed anxiety-like behavior.After 1 w SD and 2 w SD,mice showed no differences from control mice in the test of spatial learning and memory;However,the spatial learning and memory performance of 3 w SD mice were all significantly poorer than the control group.(3)By measuring related protein expression in hippocampus after long-term SD,we found the expression of BDNF of 2 w SD showed no difference from the control mice;1 w SD and 3 w SD group were both significantly lower than the control group;3 w SD group was also significantly lower than the 1 w SD group.The expression of CB1 receptor had no significant difference among the groups.Taken together,our findings show that there are some disadvantages in multiple platforms-over-water technique which cause animal stress and the new moderate mechanical technique of SD could reduce the interference of these factors and has no significant physiological stress effect.So it is more advantageous than the commonly used multiple platforms over-water technique.Short-term SD won’t induce anxiety-like behavior or spatial learning and memory deficits,while long-term intermittent SD could induce anxiety-like behavior.However,only after 3 w SD mice spatial learning and memory can be impaired.Therefor,the long-term sleep deprivation model can actually reflect the anxiety and learning and memory damage caused by chronic sleep loss.It remains uncertain if CB1 receptor mediates learning and memory impairment induced by SD;Only the expression of BDNF in hippocampus declines to a certain level can mediate the space learning and memory impairment.This finding also further validates the scientific reliability of long-term sleep deprivation models in molecular level.Our study would provide novel reference for SD study,as well as effective theoretical basis for improving the sleep loss-related cognitive disorder.