Effects of morphine and heroin on discrimination learning and consolidation in mice.
Morphine and heroin were administered to mice learning to swim toward a light source (L procedure) or toward the dark (D procedure), in a Y water maze, under pre and post-trial drug treatment conditions. In the pre-trial experiments a clear disrupting effect on performance with the two procedures followed administration of both drugs, but for the L performance never fell below the 50% level of correct choices. Analysis of the performance within each session demonstrated a disruption in the long term memory consolidation mechanism. The administration of naloxone, or alternatively, discontinuation of the treatment, was followed by a gradual improvement, in performance by the treated animals. In both procedures, a performance disruption also followed the administration of the drugs immediately after each experimental session.
D000818:Animals; D003624:Darkness; D004193:Discrimination Learning / Q000187:drug effects*; D003932:Heroin / Q000494:pharmacology*; D008027:Light; D008568:Memory / Q000187:drug effects*; D051379:Mice; D008811:Mice, Inbred DBA; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology
D009270:Naloxone; D003932:Heroin; D009020:Morphine