Morphine: Conditioned Increases in Self-Administration in Rhesus Monkeys

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Science  05 Dec 1969:
Vol. 166, Issue 3910, pp. 1306-1307
DOI: 10.1126/science.166.3910.1306


Operant responding in three monkeys was maintained by intravenous presentations of morphine. Nalorphine produced reliable increases in morphine-reinforced responding. With successive daily nalorphine injections there was adecreased latency of self-administration responding for morphine, and substituted saline injections produced conditioned increases in morphine-reinforced responding.

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