Retrieval of the aversive memory : participation of NMDA receptor and examination of Zenk expression in the hippocampus of pigeons / Evocação da memoria aversiva : participação do receptor NMDA e analise da ativação de Zenk no hipocampo de pombos

AUTOR(ES)

Maria Luiza Antunes Sperandeo

DATA DE PUBLICAÇÃO

2005

RESUMO

The present study investigated the effects of the antagonist of the glutamate NMDA receptor, MK- 801, in the activation of zenk in the hippocampus of pigeons (Hp) submitted to the classical aversive conditioning. Two groups of pigeons received MK-801 (MKG, n=6) or saline (SG, n=6) 30 min before training with tone-shock associations. The control groups received unpaired stimulation (RCG, n=6), exposure to the context (CCG=7) or manipulation alone (MG=4). During the 20 min training session MKG and SG received three sound (1000-Hz, 83 dB, 1 s) and shock associations (10 mA, 35ms). The test to the context occurred 24 hours after the training. During the training session SG animals showed more freezing as compared with CCG (p<0,05). During the test, SG expressed higher freezing than all the other groups (p<0,001). ZENK analysis was conducted with imunohistochemistry. The density of ZENK-positive nuclei in the ventral hippocampus, specifically in the ventromedial hippocampus, was higher for SG as compared to the other groups (p<0,01). The fact that the animals from the MKG expressed lower freezing to the context may be considered as indicative of an amnesic effect of the MK-801. The density of ZENK-positive nuclei in the hippocampus suggests a regional activation that may be related to the retrieval of contextual aversive memory. The present study indicates that synaptic mechanisms mediated by NMDA glutamate receptors participate in the neural plasticity related to the retrieval of contextual aversive memory

ASSUNTO(S)

hippocampus (brain) hipocampo (cerebro) classical conditioning memoria - fisiologia pombo physiology n-methyl-d-aspartate receptors receptores de n-metil-d-aspartato condicionamento classico memory

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