Extracellular serotonin level in the basolateral nucleus of the amygdala and dorsal periaqueductal gray under unconditioned and conditioned fear states: An in vivo microdialysis study

Autor(es)

Zanoveli, Janaina M. ^[1] ; Carvalho, Milene C. ^[1] ; Cunha, Joice M. ^[1] ; Brandao, Marcus L. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Lab Psicobiol, BR-14040901 Ribeirao Preto, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Brain Research; v. 1294, p. 106-115, OCT 6 2009.
• Citações Web of Science: 26

Resumo

Serotonin (5-HT) plays a key role in the neural circuitry mediating unconditioned and conditioned fear responses related to panic and generalized anxiety disorders. The basolateral nucleus of the amygdala (BLA) and the dorsal periaqueductal gray (dPAG) appear to be mainly involved in these conditions. The aim of this study was to measure the extracellular level of 5-HT and its metabolite 5-hydroxyindolacetic acid (5-HIAA) in the BLA and dPAG during unconditioned and conditioned fear states using in vivo microdialysis procedure. Thus, for the unconditioned fear test, animals were chemically stimulated in the dPAG with semicarbazide, an inhibitor of the gamma-aminobutyric acid-synthesizing enzyme glutamic acid decarboxylase. For the conditioned fear test, animals were subjected to a contextual conditioned fear paradigm using electrical footshock as the unconditioned stimulus. The results show that the 5-HT and 5-HIAA level in the BLA and dPAG did not change during unconditioned fear, whereas 5-HT concentration, but not 5-HIAA concentration, increased in these brain areas during conditioned fear. The present study showed that the 5-HT system was activated during conditioned fear, whereas it remained unchanged during unconditioned fear, supporting the hypothesis that 5-HT has distinct roles in conditioned and unconditioned fear (dual role of 5-HT in anxiety disorders). (C) 2009 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 08/54445-5 - Envolvimento do sistema serotonérgico e dos receptores opióides, benzodiazepínicos e canabinóides do tipo CB1 da substância cinzenta periaquedutal nas respostas condicionadas e incondicionadas de medo
• Beneficiário: Joice Maria da Cunha
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 06/54387-0 - Participacao do nucleo basolateral da amigdala na mediacao de respostas condicionadas e incondicionadas de medo geradas pela estimulacao quimica da substancia cinzenta periaquedutal dorsal.
• Beneficiário: Janaina Menezes Zanoveli
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 06/06354-5 - Psicobiologia do medo e da ansiedade
• Beneficiário: Marcus Lira Brandão
• Modalidade de apoio: Auxílio à Pesquisa - Temático