The complicated reflex complexes on the basis of orientation exploratory-behavior, emotional state and pain reaction play an important role in the analisator activity of the brain cortex. The rate of inhibition of orientation-exploratory reactions shows the intensity of the inner inhibition. In a complex with other indicators it can characterize the intensity and the mobility of the basic nerve processes of the cortex. The role of the neurosteroids has not been studied sufficiently in this direction. The results of the present study show the role of testosterone in the regulation of the horizontal and vertical locomotor activity and the latent period of the pai reaction of male immature rats. They are part of an investigation on the role of neurosteroids in adaptive reaction s. The indicator entropy of the behavior as a haracte risti of the organization of the behavior of rats in an n field study together with the probability structure of the behavior was also used. Testosterone was found to inhibit the horizontal and vertical locomotor activity of rats and prolong the latent period of the pain reaction in the tail flick test. The effect of the neurosteroid was apparent 4 hours after injection and was maintained for 24 hours. It was concluded that testosterone might play a role in the regulation of the locomotor behavioral acts and of the pain reaction. Testosterone influences all the organization of the behavior, it decreases the entropy of the behavior which is connected with a precipitation of the process of inhibition of the exploratory activity and the emotion reactivity, simultaneously changing the dynamic of the behavioral entropy 1998 Prous Science. All rights reserved.
