PT  - JOURNAL ARTICLE
AU  - D. E. McMillan
AU  - W. H. Morse
TI  - SOME EFFECTS OF MORPHINE AND MORPHINE ANTAGONISTS ON SCHEDULE-CONTROLLED BEHAVIOR
DP  - 1967 Jul 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 175--184
VI  - 157
IP  - 1
4099  - http://jpet.aspetjournals.org/content/157/1/175.short
4100  - http://jpet.aspetjournals.org/content/157/1/175.full
SO  - J Pharmacol Exp Ther1967 Jul 01; 157
AB  - The effects of morphine, nalorphine and two benzomorphan narcotic antagonists were studied under a multiple fixed-ratio, fixed-interval schedule of food presentation. At appropriate doses all of the drugs increased rate of responding under the fixed-interval component. Higher doses decreased responding under both the fixed-interval and fixed-ratio components. The rank order of potency was the same for both the rate-increasing the rate-decreasing effects, with cyclazocine being the most potent, then morphine, pentazocine and nalorphine. The effects obtained after weekly injections of morphine could be replicated, suggesting that effects of tolerance were minimal. After daily administrations of morphine, however, higher doses decreased responding less, but the same qualitative effects were still observed. © 1967 by The Williams & Wilkins Company