title: Dose-dependent impairing effects of morphine on avoidance acquisition and performance in male mice.
abstract: The effects of morphine (6.3, 12.6, and 25.2 mg/kg) on active avoidance behavior of BALB/C mice are explored in three acquisition sessions and in two subsequent performance sessions. Morphine-treated animals showed an increase in avoidance acquisition with respect to control group without differences in performance. However, a dramatical, concomitant rise in the locomotor activity of the animals (increase in the number of crossings during the intertrial intervals) prompted us to transform the data employing a formula with which a measure of actual learning was obtained. Applying this formula, we have observed that morphine administration impairs, dose-dependently, acquisition and performance of avoidance. Thus, the impairing effects of morphine on avoidance could be masked by their stimulant effects on locomotor activity.
authors.affiliation: Area de Psicobiología, Facultad de Psicología, Universitat de Valencia, Spain. asuncion.aguilar@uv.es
authors.forename: M A
authors.initials: MA
authors.lastname: Aguilar
authors.forename: J
authors.initials: J
authors.lastname: Miñarro
authors.forename: V M
authors.initials: VM
authors.lastname: Simón
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009020:Morphine / Q000494:pharmacology*; D009294:Narcotics / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D009294:Narcotics; D009020:Morphine