Targeted deletion of the GABRA2 gene encoding alpha2-subunits of GABA(A) receptors facilitates performance of a conditioned emotional response, and abolishes anxiolytic effects of benzodiazepines and barbiturates.
Pharmacol Biochem Behav
; 90(1): 1-8, 2008 Jul.
Article
em En
| MEDLINE
| ID: mdl-18313124
ABSTRACT
Mice with point-mutated alpha2 GABA(A) receptor subunits (rendering them diazepam insensitive) are resistant to the anxiolytic-like effects of benzodiazepines (BZs) in the conditioned emotional response (CER) test, but show normal anxiolytic effects of a barbiturate. We investigated the consequence of deleting the alpha2-subunit on acquisition of the CER with increasing intensity of footshock, and on the anxiolytic efficacy of a benzodiazepine, diazepam, and a barbiturate, pentobarbital. alpha2 knockout (KO) and wildtype (WT) mice were trained in a conditioned emotional response (CER) task, in which lever pressing for food on a variable interval (VI) schedule was suppressed during the presentation of a compound light/tone conditioned stimulus (CS+) that predicted footshock. The ability of diazepam and of pentobarbital to reduce suppression during the CS+ was interpreted as an anxiolytic response. There were no differences between the genotypes in shock sensitivity, as assessed by their flinch responses to increasing levels of shock. However, alpha2 KO mice showed a greater suppression of lever pressing than WT littermates in the presence of a compound cue signalling footshock. Diazepam (0, 0.5, 1 and 2 mg/kg) induced a dose-dependent anxiolytic-like effect in WT mice but no such effect was seen in KO mice. Similarly, although pentobarbital (20 mg/kg) reduced the ability of the CS+ to reduce lever pressing rates in WT mice, this effect was not seen in the KO. These findings suggest that alpha2-containing GABA(A) receptors mediate the anxiolytic effects of barbiturates, as well as benzodiazepines, and that they may be involved in neuronal circuits underlying conditioned anxiety.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ansiolíticos
/
Barbitúricos
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Benzodiazepinas
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Receptores de GABA-A
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Condicionamento Operante
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Subunidades Proteicas
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Emoções
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Pharmacol Biochem Behav
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Reino Unido