Participação de receptores noradrenérgicos na substância cinzenta periaquedutal dorsal na modulação de comportamentos defensivos relacionados à ansiedade

• Autor(a) principal: Souza, Dayane de Oliveira
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/8358
• topic: Noradrenaline; Dorsal periaqueductal gray matter; Anxiety; Light-dark test; Noradrenalina; Substância cinzenta periaquedutal dorsal; Teste de transição claro-escuro; Farmácia; Fentolamina; Ansiedade; 615

The role of the dorsal periaqueductal gray matter (DPAG) in fear and anxiety has been studied over the last decades. The evidence regarding the involvement of the noradrenergic system in anxiety is conflicting, depending on brain structure studied. Thus, in the present study we tested the hypothesis that noradrenaline injected directly into the DPAG of rats has anxiolytic-like effect in the light-dark transition test. The lightdark transition test is an ethological model of anxiety, quick and easy to perform, that does not require animal training. For this, Wistar rats were given intra-DPAG administration of noradrenaline (30, 60 or 90 nmol) or saline and tested in light-dark test. In addition, we investigated the effect of pre-treatment with intra-DPAG nonselective antagonists of alpha and beta-adrenergic receptors, phentolamine and propranolol, respectively, in the effect of noradrenaline injection in the same structure. After the tests, the animals were placed for five minutes in the open field, for measurement of locomotor activity. Our results show that noradrenaline (30 and 60 nmols) administered directly into the SCPD increased time spent in the light compartment and the number of transitions of the animals submitted to the light-dark transition test, suggesting an anxiolytic-like effect. In addition, intra-SCPD injection of norepinephrine did not change locomotor activity of animals in the open field test. The results also show that pre-treatment with intra-SCPD propranolol or phentolamine attenuated anxiolytic-like effect of norepinephrine when analyzing the time spent in the light compartment of the model. Thus, this work suggests an involvement of noradrenergic neurotransmission in the SCPD, via alpha and beta-adrenergics receptors in defensive reactions associated with generalized anxiety disorder in animals in the light-dark transition model.