Hyperalgesic effect induced by barbiturates, midazolam and ethanol: pharmacological evidence for GABA-A receptor involvement
Braz. j. med. biol. res
; 30(2): 251-6, Feb. 1997. graf
Article
em En
| LILACS
| ID: lil-188435
Biblioteca responsável:
BR1.1
ABSTRACT
The involvement of GABA-A receptors in the control of nociception was studied using the tail-flick test in rats. Non-hypnotic doses of the barbiturates phenobarbital (5-50 mg/kg), pentobarbital (17-33 mg/kg), and thiopental (7.5-30 mg/kg), of the benzodiazepine midazolam (10 mg/kg) or of ethanol (0.4-1.6 g/kg) administered by the systemic route reduced the latency for the tail-flick response, thus inducing a 'hyperalgesic' state in the animals. In contrast, non-convulsant doses of the GABA-A antagonist picrotoxin (0.12- 1.0 mg/kg) administered systemically induced an increase in the latency for the tail-flick response, therefore characterizing an 'antinociceptive' state. Previous picrotoxin (0.12 mg/kg) treatment abolished the hyperalgesic state induced by effective doses of the barbiturates, midazolam or ethanol. Since phenobarbital, midazolam and ethanol reproduced the described hyperalgesic effect of GABA-A-specific agonists (muscimol, THIP), which is specifically antagonized by the GABA-A antagonist picrotoxin, our results suggest that GABA-A receptors are tonically involved in the modulation of nociception in the rat central nervous system.
Texto completo:
1
Índice:
LILACS
Assunto principal:
Picrotoxina
/
Barbitúricos
/
Midazolam
/
Receptores de GABA-A
/
Etanol
/
Hiperalgesia
Limite:
Animals
Idioma:
En
Revista:
Braz. j. med. biol. res
Assunto da revista:
BIOLOGIA
/
MEDICINA
Ano de publicação:
1997
Tipo de documento:
Article
/
Project document