Fos Protein And Sleep Homeostatic Regulatory Mechanism

A series of findings over the past decade have begun to identify the brain circuitry and neurotransmitters that regulate our daily cycles of sleep and wakefulness. Sleep and wakefulness are regulated by circadian rhythm and the homeostatic regulation system. Little is known about specific neuronal systems that regulate homeostatic aspects of sleep control. This study examined the effects of early and late phase sleep deprivation starting at different time and sleep recovery after the deprivation on the expression of the immediate early gene c-fos in the rat brain with immunohistochemisty. These observations were discussed with respect to the homeostatic regulation of sleep and to the functional consequences of wakefulness in specific brain areas. Our findings will add evidence to clarify the homeostatic aspects of sleep control as well as to elucidate the function of flip-flop switch in the homeostatic regulation of sleep.The main effects of early phase sleep deprivation (7:00-13:00) on the sleep-wake architecture during sleep recovery time:NREM sleep power density increased in 1.5-3 Hz accompanied by delta energy increasing. Stage transition numbers of NREM sleep to wakefulness decreased from 26 to 16, and of wakefulness to NREM sleep decreased from 37 to 23 in 2 hours. The bouts of NREM sleep episode over 32-64 sec and 64-128 sec decreased to 38% and 33% respectively, while the bouts of NREM sleep episode at 1024-2048 sec increased to 9-fold before. The main effects of late phase sleep deprivation (13:00-19:00) on the sleep-wake architecture during sleep recovery time:amount of wakefulness decreased accompanied by NREM sleep increased from 30 min/2 h to 60 min/2 h. Stage transition numbers increased but with no statistical difference. The bouts of NREM sleep episode over 512-1024 sec increased to 3.5-fold before.Immunohistochemisty results showed:the VLPO cluster neurons manifesting Fos-IR was elevated to 2.6 and 2.5-fold during early and late recovery sleep respectively after total sleep deprivation. Number of Fos-IR neurons in the MnPO increased to 1.1 and 1.5-fold during sleep recovery time after early and late phase sleep deprivation. Numbers of neurons expressing c-Fos-IR in the VTM were significantly decreased to 27% and 51% after early and late phase sleep recovery compared with sleep deprivation while this were 24% only after early phase sleep recovery in the DTM. The same result were showed in the LC, c-Fos-IR in this area decreased to 28% that of early sleep deprivation time. Numbers of neurons c-Fos-IR in the DRN were significantly decreased to 52% and 44% after early and late phase sleep recovery compared with sleep deprivation time. In contrast, Fos-IR neurons in the piriform and the cingulate cortex were most prevalent after sleep recovery. Fos-IR neurons in the piriform cortex increased to 2 times that of sleep deprivation time after early phase of sleep recovery. Fos-IR neurons in the cingulate cortex increased to 1.5 and 1.6-fold that of sleep deprivation time. The number of Fos-IR neurons in the vlPAG and the LPT manifesting is decreased to 80% and 52% during recovery sleep after total sleep deprivation. Numbers of neurons c-Fos-IR in the PPT were significantly decreased to 73% and 75% after early and late phase sleep recovery compared with sleep deprivation time.These results indicated:the VLPO cluster is more related to NREM sleep regulation. The activation of neurons in the VLPO and MnPO is associated with increasing sleep amount and not with increasing homeostatic sleep drive/pressure. The activation of neurons in the VLPO cluster inhibits neurons in the TMN and ensures the start of sleep. The piriform and cingulate cortex are both take part in the homeostatic regulation of sleep. Amount and power density of REM sleep exhibited no statistical difference for the reason of both REM-on and REM-off neurons decreased their activity.1. Power density of NREM sleep increased and stage transition numbers of NREM sleep to wakefulness and of wakefulness to NREM sleep decreased; short NREM sleep episode numbers decreased accompanied by longer NREM sleep episode numbers increased during early phase of sleep recovery. 2. Amount of NREM sleep increased accompanied by more stage transition numbers as well as short and longer NREM sleep episode numbers exhibited trend of increase.3. The activation of neurons in the VLPO and MnPO is associated with increasing sleep amount and without increasing homeostatic sleep drive/pressure.4. The activation of neurons in the VLPO cluster inhibits neurons in the TMN and ensure the start of sleep.5. The piriform and cingulate cortex are both take part in the homeostatic regulation of sleep. One of major inconveniences encountered in sleep studies is the time-consuming labor involved in EEG analysis. This study was designed to find the optimal EEG epoch duration that vividly reveals animals' sleep-wake profiles and relieve researchers from the laborious analysis of rodent sleep-wake parameters. We analyzed mouse and rat EEG signals by often-used epoch durations (4,8,10,20, and 30 sec) and compared the difference in sleep-wake profiles in terms of amounts of sleep and wakefulness, number and duration of episodes, number of sleep-wake stage transitions, and EEG power spectra.There were no statistical differences in the amount and EEG power density of wakefulness, non-rapid eye movement (non-REM, NREM), and REM sleep among the 5 epoch durations we used. However, the shorter the epoch, the more numerous the stage transitions and the larger the episode number. Setting the epoch duration depends on the outcome of experimental purposes. When the amount of each stage and power density of EEG signals are desired, a 30-sec epoch duration is an appropriate option to save time; and the results obtained are not different from those found by analysis of other epoch durations. If stage transition and duration and number of episodes are considered, a 4-sec epoch duration is suggested to be the best choice for analysis.1. Setting the epoch duration depends on the outcome of experimental purposes.2. When the amount of each stage and power density of EEG signals are desired, a 30-sec epoch duration is an appropriate option to save time.3. If stage transition and duration and number of episodes are considered, a 4-sec epoch duration is suggested to be the best choice for analysis. Conventional analysis of EEG signals for sleep scoring is based on the time domain assessment of wave patterns. Human experts carry out this task relying on the direct visualization of EEG epochs. The present work aimed to develop a simple computer-based, sleep scoring algorithm that categorizes three vigilance states including sleep stage (non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep) and wakefulness based on enquire frequency domain recur to relative thresholds. A variety of frequency and time-domain features were extracted from each 4-s epoch of the retrospective mice 24-h sleep data with application of a algorithm was implemented using Matlab version 7.0 (The Mathworks, Natick, MA). This algorithm is composed of five steps. Step 1, to determine EMG power-ratio. Step 2, the three area were determined by thresholds of 5.5 and 6 i.e. high energy, middle energy and low energy areas. Step 3, to acquire ratio ofθ/δ. Step 4, to distinguish wake from NREM sleep byθ/δratio in middle energy area, and Step 5, to distinguish REM from NREM sleep byθ/δratio in low energy area.The method achieved a high degree of>91% agreements with the waveform recognition procedure. The algorithm is a reliable tool for automatic three vigilance states detection, overcoming the inconsistency of manual scoring and reducing the time taken by experts.1. The average accuracy of the computer based algorithm were 90.6±1.4% when compared with visual scoring.2. The accuracy for each vigilance state were 94.60±3.24% for wake,92.62±3.05% for NREM sleep.3. The algorithm is a reliable tool for automatic three vigilance states detection.