Region-specific changes of GABAA receptors by tolerance to and dependence upon pentobarbital.
Eur J Pharmacol
; 236(1): 23-30, 1993 May 12.
Article
em En
| MEDLINE
| ID: mdl-8391453
ABSTRACT
An experimental model for inducing tolerance to and dependence upon pentobarbital was characterized. Rats were infused with pentobarbital, 300 micrograms/10 microliter per h i.c.v. for 6 or 7 days, through pre-implanted cannulas by osmotic minipumps. Measurement of brain and serum levels showed that pentobarbital remained mainly inside of the brain. Measurements of sleeping time and susceptibility to convulsant-induced seizures indicated a substantial degree of tolerance and dependence (24 h after termination of infusion). Results of GABAA receptor binding assays showed marked regional variations. While [35S]t-butylbicyclophosphorothionate (TBPS) binding sites were increased in frontal cortices and striata of pentobarbital-dependent animals, KD was increased in striata of tolerant animals. Dependence upon pentobarbital was correlated with increased [3H]flunitrazepam binding sites in all three regions examined. Both high and low affinity [3H]muscimol binding sites were increased in dependent animals, but low affinity sites were decreased in frontal cortices of tolerant animals. KDs of [3H]muscimol high affinity sites were increased in cerebellum after animals developed dependence upon pentobarbital. KDs of [3H]muscimol low affinity sites were decreased in striata of pentobarbital tolerant animals. These findings further support the hypothesis that GABAA receptors in discrete areas of the brain have different subunit compositions and are regulated differentially by pharmacological modulators.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Pentobarbital
/
Receptores de GABA-A
/
Compostos Bicíclicos Heterocíclicos com Pontes
/
Transtornos Relacionados ao Uso de Substâncias
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
1993
Tipo de documento:
Article