Effects of reversible inactivation of the dorsomedial hypothalamus on panic- and anxiety-related responses in rats

Effects of reversible inactivation of the dorsomedial hypothalamus on panic- and anxiety-related responses in rats

Author Nascimento, Juliana Olivetti Guzman Autor UNIFESP Google Scholar
Zangrossi Junior, Helio Google Scholar
Viana, Milena de Barros Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Universidade de São Paulo (USP)
Abstract The medial hypothalamus is part of a neurobiological substrate controlling defensive behavior. It has been shown that a hypothalamic nucleus, the dorsomedial hypothalamus (DMH), is involved in the regulation of escape, a defensive behavior related to panic attacks. The role played by the DMH in the organization of conditioned fear responses, however, is less clear. In the present study, we investigated the effects of reversible inactivation of the DMH with the GABA A agonist muscimol on inhibitory avoidance acquisition and escape expression by male Wistar rats (approximately 280 g in weight) tested in the elevated T-maze (ETM). In the ETM, inhibitory avoidance, a conditioned defensive response, has been associated with generalized anxiety disorder. Results showed that intra-DMH administration of the GABA A receptor agonist muscimol inhibited escape performance, suggesting an antipanic-like effect (P < 0.05), without changing inhibitory avoidance acquisition. Although a higher dose of muscimol (1.0 nmol/0.2 µL; N = 7) also altered locomotor activity in an open field when compared to control animals (0.2 µL saline; N = 13) (P < 0.05), the lower dose (0.5 nmol/0.2 µL; N = 12) of muscimol did not cause any motor impairment. These data corroborate previous evidence suggesting that the DMH is specifically involved in the modulation of escape. Dysfunction of this regulatory mechanism may be relevant in the genesis/maintenance of panic disorder.
Keywords Muscimol
Generalized anxiety disorder
Panic disorder
Dorsomedial hypothalamus
Elevated T-maze
Language English
Sponsor Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Date 2010-09-01
Published in Brazilian Journal of Medical and Biological Research. Associação Brasileira de Divulgação Científica, v. 43, n. 9, p. 869-873, 2010.
ISSN 0100-879X (Sherpa/Romeo, impact factor)
Publisher Associação Brasileira de Divulgação Científica
Extent 869-873
Origin https://dx.doi.org/10.1590/S0100-879X2010007500075
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000283262800009
SciELO ID S0100-879X2010000900009 (statistics in SciELO)
URI https://repositorio.unifesp.br/handle/11600/5921

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