Effect of cortisol on a model of stereotyped behavior of rabbits in the form of thumping.

Experiments conducted on 10 adult male Chinchilla rabbits showed that single 5-sec electrostimulation of the region of the medial hypothalamus induces a series of stereotyped behavioral responses in the form of synergic thumping on the floor of the experimental chamber. When the stimuli are repeated every 1.5-2 min adaptation to stimulation is observed, which is expressed in a gradual decrease of the number of thumps. To study the pharmacological and hormonal effects on the described behavior, an experimental model is proposed which consists of two series of stimulation, each of which consists of 10 successive stimuli. The investigated pharmacological agent (cortisol [hydrocortisone] hemisuccinate) was injected into the animals in the interval between the two series of stimulation. A statistical analysis of the experimental results showed that intraperitoneal injection of cortisol in doses of 10 and 20 mg/kg enhances the simulation-induced behavioral response and shortens the latent period of its manifestation compared with the control. Key words: rabbit, electrostimulation, medial hypothalamus, stereotyped behavior, cortisol.