[Changes in the wakefulness-sleep cycle in mice induced by endogenous substances from the tissues of the susliks Citellus parryi and C. undulatus during hibernation].

Intraabdominal injections of albino mice of extracts from the brain (2mg/g) and epithelial tissue of the small intestine (1.3 mg/g) of hibernating ground squirrels result within 6 hours in the decrease of the duration of the awake state (by 2.1-2.4 times), inhibition of paradoxical sleep, the increase in the duration of the slow wave sleep, and the decrease in the brain temperature (by 4.5-6 degrees). These indices are affected to a significantly lower extent by injections of intestinal extracts from non-hibernating animals. It is suggested that in homoiothermic animals, changes of temperature homeostasis and sleep cycle are controlled by endogeneous substances which are present in the brain and tissues of the internal organs.