Amnestic effect of cocaine after the termination of its stimulant action |
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Authors: | ST Niigaki RH Silva CL Patti JLS Cunha SR Kameda JC Correia-Pinto AL Takatsu-Coleman R Levin VC Abílio R Frussa-Filho |
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Affiliation: | 1. Department of Pharmacology, Universidade Federal de São Paulo, R. Botucatu, 862, Ed. Leal Prado, 1 andar, 04023062, São Paulo, SP, Brazil;2. Department of Physiology, Universidade Federal do Rio Grande do Norte, Av. Salgado Filho, s/n, 59078900, Natal, Brazil |
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Abstract: | The effects of cocaine on memory are controversial. Furthermore, the psychostimulant action of cocaine can be a critical issue in the interpretation of its effects on learning/memory models. The effects of a single administration of cocaine on memory were investigated during the presence of its motor stimulating effect or just after its termination. The plus-maze discriminative avoidance task (PM-DAT) was used because it provides simultaneous information about memory, anxiety and motor activity. In Experiment I, mice received saline, 7.5, 10, 15 or 30 mg/kg cocaine 5 min before the training session. In Experiment II, mice were trained 30 min after the injection of saline, 7.5, 10, 15 or 30 mg/kg cocaine. In Experiment III, mice received 30 mg/kg cocaine 30 min pre-training and pre-test. In Experiment IV, mice received 30 mg/kg cocaine immediately post-training. Tests were always conduced 24 h following the training session. Given 5 min before training, cocaine promoted a motor stimulant effect at the highest dose during the training session but did not impair memory. When cocaine was injected 30 min pre-training, the drug did not modify motor activity, but produced marked amnestic effects at all doses tested. This amnesia induced by cocaine given 30 min pre-training was not related to a state-dependent learning because it was not abolished by pre-test administration of the drug. Post-training cocaine administration did not induce memory deficits either. Our results suggest that the post-stimulant phase is the critical moment for cocaine-induced memory deficit in a discriminative task in mice. |
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Keywords: | PM-DAT discriminative avoidance task Sal (or sal) saline Coc (or coc) cocaine |
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