RESUMEN
This study investigated the effect of the AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 2.5 and 5.0 nmol/side) microinjected into the core and shell sub-regions of the accumbens (Acb) nucleus, on food intake and the level of anxiety in female rats. Bilateral microinjections of CNQX (5.0 nmol/side) into the Acb shell (AP, +1.08 to +2.04), but not into the Acb core, induced an anxiolytic-like effect in relation to rats microinjected with vehicle, since the animals exhibited low level of SAP in the feeding test. The anxiolytic-like effect induced by 5.0 nmol CNQX microinjection into the Acb shell may not be ascribed to changes in the motor activity of the animals, because the frequency of locomotion, rearing and grooming remained unchanged after the drug microinjection. However, neither Acb shell nor Acb core CNQX microinjections were able to change the animals food intake along 1h feeding behaviour evaluation. Food intake remained unchanged 24h after the drug microinjections either into the Acb shell or into the Acb core. The data suggest that AMPA receptor blockade in the Acb nucleus may differentially change the ingestive and defensive behaviours in female rats.
Asunto(s)
6-Ciano 7-nitroquinoxalina 2,3-diona/farmacología , Ingestión de Alimentos/efectos de los fármacos , Actividad Motora/efectos de los fármacos , Núcleo Accumbens/efectos de los fármacos , Receptores AMPA/antagonistas & inhibidores , 6-Ciano 7-nitroquinoxalina 2,3-diona/administración & dosificación , Análisis de Varianza , Animales , Ansiedad/fisiopatología , Ansiedad/psicología , Conducta Animal/efectos de los fármacos , Conducta Animal/fisiología , Relación Dosis-Respuesta a Droga , Ingestión de Alimentos/fisiología , Antagonistas de Aminoácidos Excitadores/administración & dosificación , Antagonistas de Aminoácidos Excitadores/farmacología , Conducta Exploratoria/efectos de los fármacos , Conducta Exploratoria/fisiología , Miedo/psicología , Femenino , Preferencias Alimentarias/efectos de los fármacos , Preferencias Alimentarias/fisiología , Aseo Animal/efectos de los fármacos , Aseo Animal/fisiología , Microinyecciones , Actividad Motora/fisiología , Núcleo Accumbens/metabolismo , Ratas , Ratas Wistar , Factores de TiempoRESUMEN
The hippocampus and amygdala, the entorhinal cortex and the parietal cortex participate, in that sequence, both in the formation and in the expression of memory for a step-down inhibitory avoidance task in rats. Bilateral infusion of AP5 or muscimol caused retrograde amnesia when given 0 min after training into both hippocampus and amygdala, when given or 180 min after training into the entorhinal cortex, or when given 180 min after training into the parietal cortex. Therefore, memory formation requires the sequential and integrated activity of all these areas mediated by glutamate NMDA receptors in each case. Pre-test administration of CNQX 1 day after training into hippocampus and amygdala, 1 or 31 days after training in entorhinal cortex, or 1, 31 or 60 days after training in the parietal cortex temporarily blocked retention test performance. Therefore, 1 day after training, all these brain structures are necessary for retrieval; 1 month later, the hippocampus and amygdala are no longer necessary for retrieval but the entorhinal and parietal cortex still are; and 60 days after training only the parietal cortex is needed. In all cases the mechanisms of retrieval require intact glutamate AMPA receptors.