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

Autor(es)

Donatti, Alberto Ferreira ^[1] ; Andrade Leite-Panissi, Christie Ramos ^{[2, 1]}

Afiliação do(s) autor(es)

^[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

• Tipo de documento: Artigo Científico
• Fonte: Brain Research Bulletin; v. 79, n. 6, p. 358-364, AUG 14 2009.
• Citações Web of Science: 10

Resumo

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)

• Processo FAPESP: 08/04150-9 - Participação dos receptores ionotrópicos glutamatérgicos no núcleo magno da rafe na hiperventilação e hipotermia induzidas por hipóxia e por hipercapnia
• Beneficiário: Aline Aparecida Ferrarese Tiballi
• Modalidade de apoio: Bolsas no Brasil - Programa Capacitação - Treinamento Técnico
• Processo FAPESP: 05/00096-1 - Avaliação anátomo-funcional do comportamento defensivo de imobilidade tônica em cobaias
• Beneficiário: Christie Ramos Andrade Leite Panissi
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 05/60760-2 - Avaliação anátomo-funcional do comportamento defensivo de imobilidade tônica em cobaias
• Beneficiário: Aline Aparecida Ferrarese Tiballi
• Modalidade de apoio: Bolsas no Brasil - Programa Capacitação - Treinamento Técnico