CONDITIONED FEAR IN LOW- AND HIGH-ANXIOUS RATS IS DIFFERENTIALLY REGULATED BY CORTICAL SUBCORTICAL AND MIDBRAIN 5-HT1A RECEPTORS

Autor(es)

Ferreira, R. ^{[1, 2]} ; Nobre, M. J. ^{[1, 3, 2]}

Afiliação do(s) autor(es)

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

^[2] Inst Neurociencias & Comportamento INeC, BR-14040901 Ribeirao Preto, SP - Brazil

^[3] Uni FACEF, Dept Psicol, BR-14401135 Franca, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Neuroscience; v. 268, p. 159-168, MAY 30 2014.
• Citações Web of Science: 13

Resumo

Interactions between the prelimbic cortex and the basolateral amygdala underlie fear memory processing, mostly through acquiring and consolidating the learning of a conditioned fear. More recently, studies highlighted the role of the dorsal periaqueductal gray (DPAG) in the modulation of learning fear responses. In addition, extensive data in the literature have signaled the importance of serotonin (5-HT) on fear and anxiety. In the present study, the role of 5-HT neurotransmission of the prelimbic cortex, basolateral amygdala or the DPAG on the unconditioned and conditioned fear responses in rats previously selected as low-(LA) or high-anxious (HA) were assessed through local infusions of 5-HT itself (10 nmol/0.2 mu l) or the selective 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT - 0.3 mu g/0.2 mu l). Behavioral analysis was conducted using the fear-potentiated startle (FPS) procedure. Dependent variables recorded were the latency and amplitude of the unconditioned startle response and FPS. Our findings suggest that, on the prelimbic cortex, 5-HT modulates the expression of conditioned fear response in HA rats and this modulation is dependent on 5-HT1A receptors. This is not true, however, for the basolateral amygdala or the DPAG. In these regions LA but not HA rats were susceptible to the anxiolytic-like effect of 5-HT1A receptor activation. It is thought that the expression of conditioned fear in HA subjects may be dependent on other 5-HT receptors, as the 5-HT1B subtype, and/or changes in other systems such as the GABA and glutamate neurotransmitters. These results increase our understanding of the rostrocaudal influence of 5-HT on the unconditioned and conditioned fear responses in LA and HA subjects and, to some extent, are in disagreement with the theoretical current that emphasizes the role of 5-HT on anxiety, mainly at the subcortical and midbrain levels. (C) 2014 IBRO. Published by Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 10/15157-4 - Ansiedade traço e enriquecimento ambiental como fatores determinantes no desenvolvimento e funcionamento do circuito de recompensa e aversão de ratos tornados dependentes de álcool ou morfina
• Beneficiário: Manoel Jorge Nobre Do Espirito Santo
• Modalidade de apoio: Auxílio à Pesquisa - Regular