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

Autor(es)

Diniz, L. ^[1] ; dos Reis, B. B. ^[2] ; de Castro, G. M. ^[2] ; Medalha, C. C. ^[2] ; Viana, M. B. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Paulo, Dept Psiquiatria, Sao Paulo - Brazil

^[2] Univ Fed Sao Paulo, Dept Biociencias, BR-11060001 Santos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Brazilian Journal of Medical and Biological Research; v. 44, n. 10, p. 1048-1053, OCT 2011.
• Citações Web of Science: 14

Resumo

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. (AU)

• Processo FAPESP: 08/58815-1 - Efeito da administracao cronica de corticosterona sobre medidas de ansiedade e memoria e sobre a neurogenese hipocampal
• Beneficiário: Milena de Barros Viana
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 09/50830-4 - Efeito da administração crônica de corticosterona sobre medidas de ansiedade e memória e sobre a neurogênese hipocampal
• Beneficiário: Leila Diniz
• Modalidade de apoio: Bolsas no Brasil - Doutorado