Browsing by Subject "Memory consolidation"
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- PublicationOpen AccessPost-training scopolamine treatment induced maladaptive behavior in open field habituation task in rats(Public Library of Science (PLoS), 2014-06-17) Caballero Bleda, María; Popovic, Natalija; Popovic Popovic, Miroljub; Anatomía Humana y Psicobiología; Research Institute of Aging, University of MurciaThe effects of scopolamine on memory consolidation are controversial and depend on several factors (i.e. site of administration, time of administration and testing, dose, cognitive task, experimental protocol, specie, strain, etc.). Generally, the range dose of systemic administered scopolamine, used in memory consolidation studies, has varied from 0.05 to 50 mg/kg. However, according to the literature, the most frequently used doses of scopolamine efficient on memory consolidation, are 1 and 30 mg/kg, low and high doses, respectively. In open field habituation studies only lower doses of scopolamine were used to test memory consolidation. Therefore, in the present study we compared the effects of low (1 mg/kg) and high (30 mg/kg) scopolamine dose, on the open field habituation task, in male Wistar rats. Scopolamine was administered immediately after the acquisition task and animals were retested 48 h later on. On the retested day, the ambulation and rearing in the open field decreased in the same manner in all tested groups. In saline- and 1 mg/kg scopolamine-treated animals, the time spent in grooming significantly decreased in the habituation task, while the same parameter significantly increased in animals treated with 30 mg/kg of scopolamine. The defecation rate significantly decreased (control group), maintained (1 mg/kg of scopolamine treated animals) or significantly increased (30 mg/kg of scopolamine treated group) on retention test. In conclusion, the present data suggest that post-training scopolamine administration does not affect locomotion neither exploration in the habituation to a novel environment, but increases defecation and grooming, two behaviours associated with fearful and stressful situations.
- PublicationRestrictedTime course of scopolamine effect on memory consolidation and forgetting in rats(Elsevier, 2014-11-18) Giménez de Béjar, Verónica; Caballero Bleda, María; Popovic, Natalija; Popovic Popovic, Miroljub; Anatomía Humana y PsicobiologíaThe 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.
- PublicationOpen AccessVerapamil blocks scopolamine enhancement effect on memory consolidation in passive avoidance task in rats(Frontiers Media, 2017-08-23) Giménez de Béjar, Verónica; Caballero Bleda, María; Popovic, Natalija; Popovic Popovic, Miroljub; Anatomía Humana y PsicobiologíaOur recent data have indicated that scopolamine, a non-selective muscarinic receptor antagonist, improves memory consolidation, in a passive avoidance task, tested in rats. It has been found that verapamil, a phenylalkylamine class of the L-type voltage-dependent calcium channel antagonist, inhibits [3H] N-methyl scopolamine binding to M1 muscarinic receptors. However, there are no data about the effect of verapamil on memory consolidation in the passive avoidance task, in rats. The purpose of the present study was to examine the effects of verapamil (0.5, 1.0, 2.5, 5.0, 10, or 20 mg/kg i.p.) as well as the interaction between scopolamine and verapamil on memory consolidation in the step-through passive avoidance task, in Wistar rats. Our results showed that verapamil (1.0 and 2.5 mg/kg) administered immediately after the acquisition task significantly increased the latency of the passive avoidance response, on the 48 h retested trial, improving memory consolidation. On the other hand, verapamil in a dose of 5 mg/kg, that per se does not affect memory consolidation, significantly reversed the memory consolidation improvement induced by scopolamine (1 mg/kg, i.p., administered immediately after verapamil treatment) but did not change the passive avoidance response in rats treated by an ineffective dose of scopolamine (30 mg/kg). In conclusion, the present data suggest that (1) the post-training administration of verapamil, dose-dependently, improves the passive avoidance response; (2) verapamil, in ineffective dose, abolished the improvement of memory consolidation effect of scopolamine; and (3) exists interaction between cholinergic muscarinic receptors and calcium homeostasis-related mechanisms in the consolidation of emotional memory.
- PublicationOpen AccessVerapamil parameter- and dose-dependently impairs memory consolidation in open field habituation task in rats(Frontiers Media, 2017-01-10) Giménez de Béjar, Verónica; Caballero Bleda, María; Popovic, Natalija; Popovic Popovic, Miroljub; Anatomía Humana y PsicobiologíaThe purpose of the present study was to examine the effects of the phenylalkylamine class of the L-type voltage-dependent calcium channel antagonist, verapamil (1.0, 2.5, 5.0, or 10 mg/kg i.p.), administered immediately after the acquisition task, on memory consolidation of the open field habituation task, in male Wistar rats. On the 48 h retested trial, all tested parameters (ambulation in the side wall and in the central areas, number of rearing, time spent grooming and defecation rate) significantly decreased in the saline treated animals. A significant decrease of rearing was observed in all verapamil treated groups. On the retention day, the ambulation in the side wall and central areas significantly decreased in the animals treated with 1 mg/kg and 10 mg/kg of verapamil, while the time spent grooming and the defecation rate significantly decreased only in the group treated with 1 mg/kg of verapamil. According to the change ratio scores that correct the individual behavioral baseline differences during initial and final sessions, habituation deficit was found in animals treated with verapamil as follows: ambulation along the side wall area (1, 2.5, and 5 mg/kg), number of rearing (all used dose) and time spent grooming (2.5, 5, and 10 mg/kg). In conclusion, the present data suggest that the post-training administration of verapamil, parameter- and dose-dependently, impairs the habituation to a novel environment.