Effects of reversible inactivation of the dorsomedial hypothalamus on panic- and anxiety-related responses in rats
Braz. j. med. biol. res
;
43(9): 869-873, Sept. 2010. ilus
Artigo
em Inglês
| LILACS
| ID: lil-556857
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.
Texto completo:
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Índice:
LILACS (Américas)
Assunto principal:
Transtornos de Ansiedade
/
Transtorno de Pânico
/
Agonistas de Receptores de GABA-A
/
Hipotálamo
/
Muscimol
Tipo de estudo:
Estudo de etiologia
Limite:
Animais
Idioma:
Inglês
Revista:
Braz. j. med. biol. res
Assunto da revista:
Biologia
/
Medicina
Ano de publicação:
2010
Tipo de documento:
Artigo
País de afiliação:
Brasil
Instituição/País de afiliação:
Universidade Federal de São Paulo/BR
/
Universidade de São Paulo/BR
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