title: Explicitly unpaired delivery of morphine and the test situation: extinction and retardation of tolerance to the suppressing effects of morphine on locomotor activity.
mesh_terms: D000818:Animals; D003214:Conditioning, Classical / Q000187:drug effects*; D004361:Drug Tolerance; D005108:Extinction, Psychological / Q000187:drug effects*; D005260:Female; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D009115:Muridae; D012931:Social Environment
chemical_list: D009020:Morphine