Comparative characteristics of the discriminative and analgesic effects of morphine

Experiments on mice were made to study and compare the discriminative and analgesic effects of morphine. The time-course of tolerance to the drug effects was found to be different. The Schild method permitted one to determine significantly different characteristics of naloxone antagonism (pA2) as regards the analgesic and discriminative effects of morphine. The data obtained attest to the different mechanisms of the analgesic and discriminative effects of morphine.