Participation of beta-endorphin in the regulation of conditioned reflex activity of cats.

The role of beta-endorphin in the regulation of conditioned instrumental food-procuring reactions and more complex forms of nervous activity such as reflexes of choice of the side of reinforcement was studied in cats. It was established that the subcutaneous injection of small doses of beta-endorphin (10 micrograms/kg, 15 x 10(-6) micrograms/kg) exerts a facilitatory nonspecialized effect on positive and negative food-procuring conditioned reflexes that has an overall adaptive character overall. The influence of the same doses of beta-endorphin on conditioned reflexes of choice is more complex in character, depending upon the initial level of conditioned reflex activity and on the typological features of the experimental animals. A possible mechanism of the influence of beta-endorphin on higher nervous activity is discussed.