Interactions between ACTH, morphine, and naloxone and their effects on locomotor behavior

A series of behavioral experiments were performed to evaluate possible interactions between ACTH, morphine and naloxone with regard to locomotor activity in an open field. Manipulations included the administration of one of the drugs followed 30 min later by one of the other drugs. This allowed the examination of the effects of a drug on the ongoing behavior induced by the other drug. In two other experiments which differed in the time of day they were run, locomotor patterns as the result of the administration of combinations of the three drugs were examined for three hours. The results of the present experiments suggest a possible common mode of action of ACTH, opiate agonists and antagonists that was dependent on time of day and stress intensity.