Paradoxical antagonism by bicuculline of the inhibition by baclofen of the electrically evoked release of [3H]GABA from rat cerebral cortex slices.
The presynaptic regulation of the electrically evoked release of [3H]GABA was studied in the rat cerebral cortex. Among the GABA receptor agonists tested (GABA, SL 75102, muscimol, THIP, isoguvacine, (+/-)-baclofen), only (+/-)-baclofen inhibited the stimulation-evoked release of [3H]GABA. This effect of baclofen was stereoselective in favor of the (-) enantiomer. The inhibition by (+/-)-baclofen of the electrically evoked release of [3H]GABA was antagonized by bicuculline and picrotoxin. Our results suggest that the release of [3H]GABA in vitro can be modulated by a receptor-mediated mechanism which is sensitive to baclofen, bicuculline and picrotoxin but not to GABA, muscimol or THIP.
Maurin
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Y
Department of Biology, Laboratoire d'Etudes et de Recherches Synthélabo, Paris, France.
D000818:Animals; D001418:Baclofen / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D001640:Bicuculline / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000187:drug effects / Q000502:physiology; D013237:Stereoisomerism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism* / Q000494:pharmacology
D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; D001418:Baclofen; D001640:Bicuculline