Effects of chronic corticosterone and imipramine administration on panic and anxiety-related responses

Effects of chronic corticosterone and imipramine administration on panic and anxiety-related responses

Author Diniz, Leila Autor UNIFESP Google Scholar
Dos Reis, B.b. Autor UNIFESP Google Scholar
De Castro, G.m. Autor UNIFESP Google Scholar
Medalha, Carla Christina Autor UNIFESP Google Scholar
Viana, Milena de Barros Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract It is known that chronic high levels of corticosterone (CORT) enhance aversive responses such as avoidance and contextual freezing. In contrast, chronic CORT does not alter defensive behavior induced by the exposure to a predator odor. Since different defense-related responses have been associated with specific anxiety disorders found in clinical settings, the observation that chronic CORT alters some defensive behaviors but not others might be relevant to the understanding of the neurobiology of anxiety. In the present study, we investigated the effects of chronic CORT administration (through surgical implantation of a 21-day release 200 mg pellet) on avoidance acquisition and escape expression by male Wistar rats (200 g in weight at the beginning of the experiments, N = 6-10/group) tested in the elevated T-maze (ETM). These defensive behaviors have been associated with generalized anxiety and panic disorder, respectively. Since the tricyclic antidepressant imipramine is successfully used to treat both conditions, the effects of combined treatment with chronic imipramine (15 mg, ip) and CORT were also investigated. Results showed that chronic CORT facilitated avoidance performance, an anxiogenic-like effect (P < 0.05), without changing escape responses. Imipramine significantly reversed the anxiogenic effect of CORT (P < 0.05), although the drug did not exhibit anxiolytic effects by itself. Confirming previous observations, imipramine inhibited escape responses, a panicolytic-like effect. Unlike chronic CORT, imipramine also decreased locomotor activity in an open field. These data suggest that chronic CORT specifically altered ETM avoidance, a fact that should be relevant to a better understanding of the physiopathology of generalized anxiety and panic disorder.
Keywords Corticosterone
Generalized anxiety disorder
Panic disorder
Elevated T-maze
Language English
Date 2011-10-01
Published in Brazilian Journal of Medical and Biological Research. Associação Brasileira de Divulgação Científica, v. 44, n. 10, p. 1048-1053, 2011.
ISSN 0100-879X (Sherpa/Romeo, impact factor)
Publisher Associação Brasileira de Divulgação Científica
Extent 1048-1053
Origin http://dx.doi.org/10.1590/S0100-879X2011007500117
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000295721600010
SciELO ID S0100-879X2011001000010 (statistics in SciELO)
URI http://repositorio.unifesp.br/handle/11600/6628

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