Normal Sleep Cycle of Male Albino Rats

Abstract

For the study on the sleep, especially on the paradoxical sleep, cats have been usually utilized. However, according to the purpose of the study, small animals as rats, guinea pigs are also useful. This study was designed to investigate the standard indices concerning the normal sleep cycle of albino rats during 24 hours. Nine adult male rats weighing between 280 and 350 g were used. All experiments began between 1 and 3 p.m. and lasted until the next day from October to March. Two pairs of screw electrodes were implanted in the skull overlying the frontal and occipital cortices under Nembutal anesthesia. EMG recordings were obtained from a pair of surgical suture needle inserted into the neck muscles. EKG was recorded from a suture needle electrode in a posterior paw, referred to the neck muscle. Respiration was recorded by a newly-devised pneumographic method, having a short gumm-tube fulfilled with active charcoal. For the eye movement recording, two stainless steel electrodes fixed on a plastic plate were inserted into the eyeball from the outside of the orbita. The animal preliminaly made habituated was placed in an electrically shielded, soundproof , dimly illuminated box, with an observation one-way window after the effect of operation had been over. During recording the animal was free to move around in the box to eat, drink and explore. Four states-hyper vigilance, arousal, slow wave sleep and paradoxical sleep-were distinguished from each other with the following criteria. The hyper vigilance means an active arousal during which the animals are awake with the eyes open, showing attentive movements. The arousal means a resting arousal during which the animals are awake but relaxed behaviorally. The slow wave sleep represents the state in which the animals sleep behaviorally showing spindles or slow waves in the frontal and occipital EEG, with some remnant EMG activity in the neck muscle and regular pneumogram.

The Circadian Sleep-Wakefulness Rhythm of the Golden Hamster

“…This figure is close to that found in cats [5], but very much different from that found in rabbits [3], rats [2], guinea pigs [4] and mice [7]. A similarly great amount of PS was found also in the ground squirrel, Citellus tridecemlineatus, but these latter data were based on rough documentation only [6].…”

Temporary augmentation of paradoxical sleep and slow wave sleep by inhibitors of RNA synthesis.

“…Changes in the sleep pattern induced by the drugs were investigated in comparison with the baseline recording. From the polygraph patterns, three states were defined as awake, slow wave sleep (SS) and PS according to the classification of MATSUMOTO et al (1967). SS was divided into light sleep (LS) and deep sleep (DS) depending on the polygraph patterns such that LS was defined as the state in which the EEG was 100-200 µV and 2-8 cps with regular respiration and DS as the state in which the EEG was 200-400 ,uV and 1-13 cps with regular respiration.…”