Effect of Oxytocin on the Emotional State and Behavior of Rats under Stress Conditions

Abstract

Oxytocin, a hormone exerting controlling effects on lactation, sexual and maternal behavior, and cyclic organization of sleep and wakefulness, is capable of significantly modulating reactions of the organism to the action of stressogenic stimuli. We studied the effects of injections of synthetic oxytocin on the behavioral phenomena and emotional state of rats during realization of a proconflict test induced by “punishments” (nociceptive electrical stimuli) in the process of drinking after water deprivation. Intraperitoneal injections of oxytocin in a 4.0 μg dose resulted in shortening of the delays of coming of rats to a water dish and also in an increase in the number of drinks of water punished by electrical stimulation, as compared with the corresponding indices in control animals. After oxytocin injections, the intensity of research activity of rats in the open field, in general, increased. After realization of the proconflict test, locomotor and orientational/research activities in animals preliminarily injected with oxytocin were much more intense than those in control rats (in the latter ones, these activities were sharply suppressed). Injections of oxytocin also led to certain normalization of the emotional state; after the proconflict test, negative shifts in this state in control rats were obvious. Therefore, oxytocin appreciably increases the resistivity of the organism against stress.