title: Time course of scopolamine effect on memory consolidation and forgetting in rats.
abstract: The effect of scopolamine on the consolidation and forgetting of emotional memory has not been completely elucidated yet. The aim of the present study was to investigate the time course of scopolamine effect on consolidation and forgetting of passive avoidance response. In a first experiment of the present study, we tested the effect of scopolamine (1mg/kg, i.p., immediately after acquisition), on 24h and 48h retention performance of the step-through passive avoidance task, in adult male Wistar rats. On the 24h retested trial, the latency of the passive avoidance response was significantly lower, while on the 48h retested trial it was significantly higher in scopolamine than in the saline-treated group. In a second experiment, we assessed the 24h time course of scopolamine (1mg/kg) effect on memory consolidation in passive avoidance task. We found that scopolamine administration only within the first six and half hours after acquisition improved memory consolidation in 48h retention performance. Finally, a third experiment was performed on the saline- and scopolamine-treated rats (given immediately after acquisition) that on the 48h retention test did not step through into the dark compartment during the cut-off time. These animals were retested weekly for up to first three months, and after that, every three months until the end of experiment (i.e., 15 months after acquisition). The passive avoidance response in the saline treated group lasted up to 6 weeks after acquisition, while in the scopolamine treated group 50% of animals conserved the initial level of passive avoidance response until the experiment end point. In conclusion, the present data suggest that (1) improving or impairment effect of scopolamine given in post-training periods depends on delay of retention trial, (2) memory consolidation process could be modify by scopolamine within first six and half hours after training and (3) scopolamine could delay forgetting of emotional memory.
authors.affiliation: Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, 30100 Murcia, Spain; Research Institute of Aging, University of Murcia, 30100 Murcia, Spain. Electronic address: miroljub@um.es.
authors.forename: Miroljub
authors.initials: M
authors.lastname: Popović
authors.affiliation: Department of Neurology, Santa Lucía University General Hospital, 30202 Cartagena, Spain.
authors.forename: Verónica
authors.initials: V
authors.lastname: Giménez de Béjar
authors.affiliation: Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, 30100 Murcia, Spain; Research Institute of Aging, University of Murcia, 30100 Murcia, Spain.
authors.forename: Natalija
authors.initials: N
authors.lastname: Popović
authors.affiliation: Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, 30100 Murcia, Spain; Research Institute of Aging, University of Murcia, 30100 Murcia, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Caballero-Bleda
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D008297:Male; D008568:Memory / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D012601:Scopolamine / Q000008:administration & dosage*
chemical_list: D012601:Scopolamine
keywords: Emotional memory; Forgetting; Memory consolidation; Passive avoidance; Rat; Scopolamine