Papel da neurotransmissão noradrenérgica da substância cinzenta periaquedutal dorsal na modulação de comportamentos defensivos relacionados aos transtornos de ansiedade generalizada e de pânico

Abstract

The dorsal periaqueductal gray matter (DPAG) is a midbrain structure involved in the mediation of defensive behaviors associated with generalized anxiety disorder (GAD) and panic disorder (PD). There is evidence indicating the involvement of noradrenergic neurotransmission DPAG in the modulation of anxiety, however, there is no evidence for their involvement in panic attacks. In this sense, the objective of this study was to investigate the involvement of noradrenergic neurotransmission DPAG in mediating defensive behaviors related to GAD and PD in the elevated Tmaze (ETM), an animal model that combines the inhibitory avoidance response to GAD and the escape response to PD. For this, Wistar rats were given intra-DPAG administration of noradrenaline (10, 30 or 60 nmol / 0,1μL) or saline and tested in ETM. 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 effect noradrenaline injection in the same structure. Our results show that intra-DPAG administration of noradrenaline at the highest dose impaired the acquisition of inhibitory avoidance, suggesting an anxiolytic-like effect, but no effect on the escape response in ETM.