Tolerance to Morphine-Induced Increases in [14C]Catecholamine Synthesis in Mouse Brain

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Science  04 Dec 1970:
Vol. 170, Issue 3962, pp. 1106-1108
DOI: 10.1126/science.170.3962.1106


Morphine sulfate increased the incorporation of carbon-14-labeled tyrosine into labeled catecholamines in the mouse brain. Tolerance was manifested by a shift to the right in the dose-response curve for morphine after mice were treated repeatedly with morphine. Naloxone, a specific morphine antagonist, also shifted the dose-response curve for morphine to the right.

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