Data/hora: 17/06/2024 17:50:33

Provedor de dados: | 56
País: | Brazil
Título: | Agonistic-like responses from the torus semicircularis dorsalis elicited by GABA A blockade in the weakly electric fish Gymnotus carapo
Autores: | Duarte,T.T.; Corrêa,S.A.L.; Santana,U.J.; Pereira,A.S.F.; Hoffmann,A.
Data: | 2006-07-01
Ano: | 2006
Palavras-chave: | Electric fish; Torus semicircularis dorsalis; GABA-ergic system; Electromotor modulation; Agonistic behavior.
Resumo: | Findings by our group have shown that the dorsolateral telencephalon of Gymnotus carapo sends efferents to the mesencephalic torus semicircularis dorsalis (TSd) and that presumably this connection is involved in the changes in electric organ discharge (EOD) and in skeletomotor responses observed following microinjections of GABA A antagonist bicuculline into this telencephalic region. Other studies have implicated the TSd or its mammalian homologue, the inferior colliculus, in defensive responses. In the present study, we explore the possible involvement of the TSd and of the GABA-ergic system in the modulation of the electric and skeletomotor displays. For this purpose, different doses of bicuculline (0.98, 0.49, 0.245, and 0.015 mM) and muscimol (15.35 mM) were microinjected (0.1 µL) in the TSd of the awake G. carapo. Microinjection of bicuculline induced dose-dependent interruptions of EOD and increased skeletomotor activity resembling defense displays. The effects of the two highest doses showed maximum values at 5 min (4.3 ± 2.7 and 3.8 ± 2.0 Hz, P &lt; 0.05) and persisted until 10 min (11 ± 5.7 and 8.7 ± 5.2 Hz, P &lt; 0.05). Microinjections of muscimol were ineffective. During the interruptions of EOD, the novelty response (increased frequency in response to sensory novelties) induced by an electric stimulus delivered by a pair of electrodes placed in the water of the experimental cuvette was reduced or abolished. These data suggest that the GABA-ergic mechanisms of the TSd inhibit the neural substrate of the defense reaction at this midbrain level.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2006000700013
Editor: | Associação Brasileira de Divulgação Científica
Relação: | 10.1590/S0100-879X2006000700013
Formato: | text/html
Fonte: | Brazilian Journal of Medical and Biological Research  v.39 n.7 2006
Fonte: | info:eu-repo/semantics/openAccess