Effects of reversible inactivation of the dorsomedial hypothalamus on panic- and anxiety-related responses in rats
AUTOR(ES)
Nascimento, J.O.G., Zangrossi Jr., H., Viana, M.B.
FONTE
Brazilian Journal of Medical and Biological Research
DATA DE PUBLICAÇÃO
2010-09
RESUMO
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.
Documentos Relacionados
- Effects of electroacupuncture on stress and anxiety-related responses in rats
- Effects of chronic corticosterone and imipramine administration on panic and anxiety-related responses
- On the relationships between ultrasonic calling and anxiety-related behavior in rats
- Effect of acute treatment with a water-alcohol extract of Erythrina mulungu on anxiety-related responses in rats
- Substance P in the medial amygdala: Emotional stress-sensitive release and modulation of anxiety-related behavior in rats