A participação de diferentes sistemas neuromodulatórios no hipocampo, núcleo basolateral da amígdala e córtex pré-frontal ventromedial na extinção de memórias aversivas

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

2012

RESUMO

Extinction consists of the learned inhibition of retrieval of previously acquired memory. Many forms of learning are modulated by ¿-noradrenergic, D1-dopaminergic and H2-histaminergic receptors on ventromedial prefrontal cortex (vmPFC), basolateral amygdala (BLA) and dorsal hippocampus. Therefore, the aim of this work was investigated the modulation of aversive memory extinction in these brain structures. Male Wistar rats were submitted to inhibitory avoidance paradigm (EI) or contextual fear conditioning (CCM). The drugs were infused through cannulae implanted into the DH, BLA or vmPFC immediately after the extinction session and their effects were evaluated 24 h later. D-serine (50 ¿g/side), a NMDA receptor stimulant, and SKF9188 (12.5 ¿g/side), a histamine methyl-transferase inhibitor, enhanced the consolidation of the extinction memory in EI and CCM tasks. However, AP5 (5 ¿g/side), a NMDA-antagonist, and ranitidine (17.5 ¿g/side), a H2- histaminergic antagonist, impaired the extinction of both tasks, indicated that NMDA receptors are involved in the consolidation of extinction of both tasks, and histamine H2 receptors modulate that process in all areas studied. Noradrenaline (1 ¿g/side), timolol 1 ¿g/side), a ¿-adrenergic antagonist, SKF38393 (12.5 ¿g/side) and SCH23390 (1.5 ¿g/side), D1 agonist and antagonist receptor, respectively, also affected the extinction, but their effects varied with the task and with the site of infusion, suggesting that extinction modulation by ¿- and D1 is more complex. In conclusion, the three structures investigated are activated in the aversive memory extinction and the neuromodulatory systems act of different forms in these structures.

ASSUNTO(S)

memória : fisiologia memory extinção psicológica : fisiologia extinction neuromodulatory systems contextual fear conditioning

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