Name: Johnathan Júnior Vaz Carvalho
Type: MSc dissertation
Publication date: 19/07/2016
Advisor:

Namesort descending Role
Valquíria Camin de Bortoli Advisor *

Examining board:

Namesort descending Role
Ana Paula Santana de Vasconcellos Bittencourt Internal Examiner *
Cristina Martins e Silva Internal Alternate *
Daniele Cristina de Aguiar External Examiner *
Sara Cristina Hott External Alternate *
Valquíria Camin de Bortoli Advisor *

Summary: 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 T-maze (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. Furthermore, noradrenaline injection did not alter locomotor activity of animals in the open field test, suggesting that the anxiolytic effect was not due to an increase in exploratory activity. The results also show that pre-treatment with phentolamine or propranolol attenuated anxiolytic-like effect of noradrenaline. Thus, this study suggests an involvement of noradrenergic neurotransmission in DPAG partially mediated by alpha and beta-adrenergic receptors in defensive reactions associated with GAD, but not with PD in the ETM.

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