Morphine discrimination in the pigeon using a color tracking procedure.
Pigeons were trained to discriminate 5.0 mg/kg morphine from saline. After morphine, subjects tracked the location of red response keys and after saline, the location of green keys. When stimulus generalization to other drugs was investigated dl-methadone produced morphine-like responding and this response generalization was primarily due to the l-isomer. Pretreatment with 1.0 mg/kg naloxone shifted the morphine generalization curve 10-fold to the right but only shifted the rate suppression curve 3-fold to the right. dl-Cyclazocine generated dose-related increases in responding on the red key location and in 3 of 5 birds, responses after 1.0 mg/kg were indistinguishable from those after morphine training doses. Meperidine did not produce responding on the red keys, nor did diazepam, cocaine, d-amphetamine, phencyclidine or pentobarbital. The discriminative stimulus effects of morphine are thus stereo-selective and pharmacologically specific. Generalization of responding to dl-cyclazocine but not to phencyclidine suggests that the morphine-like discriminative dl-cyclazocine cue was not due to interaction at sigma opiate receptors.
M G
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Paule
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Wenger
D000818:Animals; D003042:Cocaine / Q000494:pharmacology; D003116:Color; D010856:Columbidae; D003463:Cues; D003496:Cyclazocine / Q000494:pharmacology; D003913:Dextroamphetamine / Q000494:pharmacology; D003975:Diazepam / Q000494:pharmacology; D004192:Discrimination, Psychological / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005794:Generalization, Response / Q000187:drug effects; D008297:Male; D008614:Meperidine / Q000494:pharmacology; D008691:Methadone / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology*; D009294:Narcotics / Q000494:pharmacology; D010424:Pentobarbital / Q000494:pharmacology; D010622:Phencyclidine / Q000494:pharmacology; D011597:Psychomotor Performance / Q000187:drug effects*
D009294:Narcotics; D009020:Morphine; D008614:Meperidine; D010424:Pentobarbital; D003042:Cocaine; D010622:Phencyclidine; D003496:Cyclazocine; D003975:Diazepam; D003913:Dextroamphetamine; D008691:Methadone