Navegando por Palavras-chave "avoidance-learning"

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    Effects of amphetamine on the plus-maze discriminative avoidance task in mice
    (Springer, 2002-02-01) Silva, R. H.; Kameda, SR; Carvalho, R. C.; Rigo, G. S.; Costa, KLB; Taricano, I. D.; Frussa, R.; Universidade Federal de São Paulo (UNIFESP); Univ Santo Amaro
    Rationale: the contradictory amphetamine effects on memory could be due to different protocols of amphetamine administration or the well-known anxiogenic effect of the drug. Objective: the effects of different protocols of administration of amphetamine were investigated on mice tested in the plus-maze discriminative avoidance task (DAT), which provides simultaneous information about memory and anxiety. Methods: Acutely pre- or post-training, 0.3, 1.0, or 3.0 mg/kg amphetamine-treated, 10-day chronically 3.0 mg/kg amphetamine-treated, 0.3 mg/kg amphetamine plus 0.25 mg/kg scopolamine and 3.0 mg/kg amphetamine plus 3.0 mg/kg tacrine-treated mice were conditioned to choose between two enclosed arms (one of which was aversive) while avoiding two open arms. Learning/memory was evaluated by the percentage time in the aversive enclosed arm (PTAV), and anxiety by the percentage time in the open arms (PTO). Results: Given acutely before conditioning, amphetamine significantly decreased PTO in training, suggesting an anxiogenic effect, and significantly increased PTAV in the test, suggesting an amnestic action. Given acutely after the conditioning, no action of this drug on memory was found. After repeated treatment, the anxiogenic effect disappeared, while the amnestic effect remained. While no effects of subeffective doses of amphetamine and scopolamine co-administration were detected, tacrine attenuated the amnestic effect of amphetamine. Conclusions: Amphetamine has different effects on DAT when given pro- or post-training. While acute pre-training amnestic action is temporally correlated with an anxiogenic effect, there is tolerance to the anxiogenic but not to the amnestic effect after repeated administration. Because this acute amnestic effect of amphetamine is attenuated by tacrine, a possible relationship with cholinergic system cannot be discarded as a mechanism to amphetamine-induced amnesia in DAT.
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    The plus-maze discriminative avoidance task: a new model to study memory-anxiety interactions. Effects of chlordiazepoxide and caffeine
    (Elsevier B.V., 2000-10-30) Silva, R. H.; Frussa, R.; Universidade Federal de São Paulo (UNIFESP)
    The plus-maze discriminative avoidance paradigm is a new animal model of learning/memory that provides simultaneous information about anxiety. Mice are conditioned to choose between the two enclosed arms tin one of which light and noise are presented as aversive stimuli) while avoiding the two open arms of the apparatus. the test has the advantage of measuring, at the same time and in the same animals, learning/memory (by the percent time spent in aversive enclosed arm - PTAV) and anxiety (by the percent time spent in the open arms - PTO). the effects of chlordiazepoxide and caffeine on learning/memory and anxiety of mice tested in this paradigm were investigated. Chlordiazepoxide (5 mg/kg) significantly increased and caffeine (20 mg/kg) significantly decreased PTO during the training session, suggesting an anxiolytic and an anxiogenic effect, respectively. in the test session, chlordiazepoxide- or caffeine-treated mice presented higher PTAV, suggesting amnestic effects. Given together, chlordiazepoxide plus caffeine did not alter PTO, and the amnesic effect produced by each drug was no longer observed. It is concluded that learning/memory depends on an optimum emotional level. the pins-maze discriminative avoidance model appears to be a useful test to investigate this critical relationship between learning/memory and anxiety. (C) 2000 Elsevier Science B.V. All rights reserved.