title: Scopolamine amnesia of passive avoidance: a deficit of information acquisition.
abstract: Despite its increasing use as an animal model of memory deficit in human dementia, relatively few studies have attempted to assess the memory processes involved in the anticholinergic-induced impairment of passive avoidance retention. In the present experiments, the influence of scopolamine administered prior to or immediately following training on 24-h retention of step-through passive avoidance was studied in NMRI mice. In low doses (0.3-3.0 mg/kg ip) pretraining administration (-5 min) of scopolamine induced a very strong amnesia. Post-training scopolamine induced a significant effect only at the highest dose tested (30 mg/kg). In a retention test of longer than normal duration (600 vs 180 s), which resulted in a more favorable comparison value in the control group, an intermediate post-training dose (10 mg/kg) induced a small effect which approached significance; a finding which may account for conflicting reports in the literature concerning the ability of scopolamine to induce a post-training deficit. The pretraining effect does not appear to have been solely the result of state-dependent learning; scopolamine (3 mg/kg) administered before both the training and test sessions induced a deficit of approximately the same magnitude as that found when administered before training or before testing only. The results indicate that scopolamine can induce a small post-trial effect, presumably through an influence on consolidation processes. The much larger effect of pretrial scopolamine, however, indicates a primary influence on processes related to information acquisition. Together with findings from the literature, the present experiments suggest that scopolamine-induced amnesia partially, but not completely, models the memory deficits of human dementia.
authors.affiliation: Cassella AG, CNS Pharmacology, Frankfurt, West Germany.
authors.forename: D K
authors.initials: DK
authors.lastname: Rush
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D001921:Brain / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004597:Electroshock; D008297:Male; D008568:Memory / Q000187:drug effects*; D011939:Mental Recall / Q000187:drug effects*; D051379:Mice; D008815:Mice, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D011950:Receptors, Cholinergic / Q000187:drug effects; D012153:Retention, Psychology / Q000187:drug effects*; D012601:Scopolamine / Q000494:pharmacology*
chemical_list: D011950:Receptors, Cholinergic; D012601:Scopolamine