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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

GABAergic antagonist blocks the reduction of tonic immobility behavior induced by activation of 5-HT2 receptors in the basolateral nucleus of the amygdala in guinea pigs

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Donatti, Alberto Ferreira [1] ; Andrade Leite-Panissi, Christie Ramos [1, 2]
Total Authors: 2
[1] Univ Sao Paulo, Psychobiol Postgrad Program, Sch Philosophy Sci & Literature Ribeirao Preto, BR-14040901 Ribeirao Preto, SP - Brazil
[2] Univ Sao Paulo, Dept Morphol Stomatol & Physiol, Dent Sch Ribeirao Preto, BR-14040904 Ribeirao Preto, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Brain Research Bulletin; v. 79, n. 6, p. 358-364, AUG 14 2009.
Web of Science Citations: 10

Tonic immobility (TI) is a temporary state of profound motor inhibition induced by situations that generate intense fear, with the objective of protecting an animal from attacks by predators. A preliminary study by our group demonstrated that microinjection into the basolateral nucleus of the amygdala (BLA) of an agonist to 5-HT(1A) and 5-HT(2) receptors promoted a decrease in TI duration. In the current study, the effects of GABAergic stimulation of the BLA and the possible interaction between GABA(A) and 5-HT(2) receptors on TI modulation were investigated. Observation revealed that GABAergic agonist muscimol (0.26 nmol) reduced the duration of TI episodes, while microinjection of the GABAergic antagonist bicuculline (1 nmol) increased TI duration. Additionally, microinjection of 5-HT(2) agonist receptors (alpha-methyl-5-HT, 0.32 nmol) into the BLA decreased TI duration, an effect reversed by pretreatment with bicuculline (at the dose that had no effect per se, 0.2 nmol). Moreover, the activation of GABA(A) and 5-HT(2) receptors in the BLA did not alter the spontaneous motor activity in the open field test. These experiments demonstrated that the activation of GABA(A) and 5-HT(2) receptors of the BLA possibly produce a reduction in unconditioned fear that decreases the TI duration in guinea pigs, but this is not due to increased spontaneous motor activity, which could affect a TI episode nonspecifically. Furthermore, these results suggest an interaction between GABAergic and serotoninergic mechanisms mediated by GABA(A) and 5-HT(2) receptors. In addition, the GABAergic circuit of the BLA presents a tonic inhibitory influence on TI duration. (C) 2009 Elsevier Inc. All rights reserved. (AU)

FAPESP's process: 05/00096-1 - Functional anatomy evaluation of the defensive behavior of tonic immobility in guinea pigs
Grantee:Christie Ramos Andrade Leite Panissi
Support type: Regular Research Grants