Conditioned fear in low- and high-anxious rats is differentially regulated by cortical subcortical and midbrain 5-HT(1A) receptors.
Neuroscience
; 268: 159-68, 2014 May 30.
Article
em En
| MEDLINE
| ID: mdl-24657773
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 (10nmol/0.2µl) or the selective 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT - 0.3µg/0.2µl). 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.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ansiedade
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Encéfalo
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Condicionamento Psicológico
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Receptor 5-HT1A de Serotonina
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Medo
Limite:
Animals
Idioma:
En
Revista:
Neuroscience
Ano de publicação:
2014
Tipo de documento:
Article
País de afiliação:
Brasil
País de publicação:
Estados Unidos