[Efficiency of the "disk-over-water" method without feedback for sleep deprivation in rats].

The "disk-over-water" method, where animals are awakened by disk rotation triggered by sleep EEG signals, was efficiently used in many studies involving sleep deprivation. Recently, the modification of this method has been developed where, during the period of deprivation, the disk was rotated in accordance with a pre-set program (the "disk-over-water" method without feedback). We considered this modification as a potentially promising one for investigation of relationship between maternal sleep and litter development. However, none of these methods has been used in experiments on female rats, and efficiency of the method without feedback has never been tested using electrophysiological estimation of sleep-wake states either. Performing these tasks was the goal of the present study. Cortical EEG, hippocampal theta-activity and locomotor activity were recorded in 14 female Wistar rats underwent sleep deprivation in the "disk-over-water" setup without feedback. Three days long during the deprivation periods from 11:00 to 14:00 the disk was rotated for 8 s with 15 s intervals. REM sleep was totally eliminated during these periods, and amounts of slow wave sleep did not exceed 10% of 3 h. The results were identical both for pregnant and non-pregnant rats. The rate of sleep reduction during deprivation periods in our experimental conditions did not differ from that in the original system with the feedback. Thus the simplified "disk-over-water" method without feedback can be used in the studies involving relatively short sleep deprivation periods.