RESUMEN
This study investigated the effect of α-adrenoceptor agonists microinjected into the shell region of the accumbens nucleus (AcbSh) on feeding and anxiety-related behaviors in free-feeding rats. Male Wistar rats with a chronically implanted cannula into the AcbSh were unilaterally microinjected with either clonidine (CLON, α(2)-adrenoceptor agonist) or phenylephrine (PHEN, α(1)-adrenoceptor agonist) at the doses of 6 and 20 nmol and submitted to the elevated plus-maze (EPM), a pre-clinical test of anxiety. Immediately after the EPM test, the animals underwent food intake evaluation for 30 min. The data showed that rats microinjected with CLON (20 nmol/0.2 µl) into the AcbSh exhibited increased %Open arm time, which is compatible with an anxiolytic-like effect. The CLON-induced anxiolysis was corroborated by increased head-dipping and decreased stretched-attend posture, two ethologically derived behaviors which are fear/anxiety-motivated. The animal's locomotor activity was not changed by 20 nmol CLON microinjection into the AcbSh. However, neither dose of PHEN microinjected into the AcbSh was able to alter either the spatial-temporal or ethological variables representative of fear/anxiety and locomotion. Food intake was not altered by any dose of CLON and PHEN microinjected into the AcbSh, but the 20 nmol CLON microinjection induced increased motor activity in the feeding test. The data suggests that noradrenergic projections to the AcbSh may underlie fear/anxiety modulation through α(2)-adrenoceptor in the AcbSh, while feeding behavior was unaffected by noradrenergic modulation in the AcbSh of free-feeding rats. This article is part of a Special Issue entitled 'Anxiety and Depression'.
Asunto(s)
Agonistas alfa-Adrenérgicos/farmacología , Ansiedad/inducido químicamente , Ingestión de Alimentos/efectos de los fármacos , Miedo/efectos de los fármacos , Núcleo Accumbens/efectos de los fármacos , Análisis de Varianza , Animales , Clonidina/farmacología , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Microinyecciones , Núcleo Accumbens/fisiología , Fenilefrina/farmacología , Ratas , Ratas WistarRESUMEN
In an attempt to establish a relationship between food intake and fear/anxiety-related behaviours, the goal of this study was to investigate the effect of bilateral injections of GABAA (Muscimol, MUS, doses 25 and 50ng/side) and GABAB (Baclofen, BAC, doses 32 and 64ng/side) receptor agonists in the nucleus accumbens shell (AcbSh) on the level of fear/anxiety-like and feeding behaviours in 24h food-deprived rats. The antagonists of GABAA (Bicuculline, BIC, doses 75 and 150ng/side) and GABAB (Saclofen, SAC, doses 1.5 and 3µg/side) were also tested. The results indicated that the total number of risk assessment behaviour decreased after the injection of both doses of GABAA agonist (MUS) into the AcbSh of 24h food-deprived rats exposed to elevated plus maze. Similar results were obtained after treatment with both doses of GABAB (BAC) agonist in the AcbSh. These data indicated that the activation of both GABAA and GABAB receptors within the AcbSh caused anxiolysis in 24h food-deprived rats. In addition, feeding behaviour (food intake, feeding latency and feeding duration) remained unchanged after treatment with both GABA agonists. In contrast, both food intake and feeding duration decreased after injections of both doses of BIC (GABAA antagonist), while the feeding latency remained unchanged after treatment with both GABA antagonists in the AcbSh of 24h food-deprived rats. The treatment with SAC (GABAB antagonist) did not affect feeding behaviour. Collectively, these data suggest that emotional changes evoked by pharmacological manipulation of the GABA neurotransmission in the AcbSh are not linked with changes in food intake.
Asunto(s)
Ansiedad/psicología , Miedo/psicología , Conducta Alimentaria/efectos de los fármacos , Privación de Alimentos/fisiología , GABAérgicos/farmacología , Núcleo Accumbens , Animales , Baclofeno/análogos & derivados , Baclofeno/farmacología , Conducta Animal/efectos de los fármacos , Bicuculina/farmacología , Ingestión de Alimentos/efectos de los fármacos , Miedo/efectos de los fármacos , GABAérgicos/administración & dosificación , Agonistas del GABA/farmacología , Antagonistas del GABA/farmacología , Agonistas de Receptores de GABA-A/farmacología , Antagonistas de Receptores de GABA-A/farmacología , Agonistas de Receptores GABA-B/farmacología , Antagonistas de Receptores de GABA-B/farmacología , Masculino , Microinyecciones , Muscimol/farmacología , Núcleo Accumbens/anatomía & histología , Ratas , Ratas Wistar , Técnicas EstereotáxicasRESUMEN
Objetivo: Método: Resultados: Conclusão: Realizamos um estudo sobre os efeitos das variações na posição de colocação do fone TDH escrever por extenso 39 junto à orelha externa e suas influências na percepção fisiológica do som, colocação dos fones evita intercorrências clínicas indesejáveis, como o colabamento do meato acústico externo, que comprometem o diagnóstico audiológico.