title: Morphine dependence in rats: secondary reinforcement from environmental stimuli.
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004777:Environment; D006801:Humans; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009021:Morphine Dependence; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D012054:Reinforcement, Psychology; D013375:Substance Withdrawal Syndrome
chemical_list: D009020:Morphine