Article date: 1988/10/1
PubMed ID: 2853310
Journal name: Neuropharmacology (ISSN: 0028-3908)
The effects of various benzodiazepine receptor ligands on the GABA autoreceptor have been studied in slices of cerebral cortex of the rat. The GABAA receptor agonist muscimol inhibited the K+-stimulated release of [3H]GABA with a pIC25 of 7.65 +/- 0.11. This effect was antagonised by the GABAA receptor antagonist bicuculline, which had an IC50 of 0.36 +/- 0.03 microM. Small concentrations (less than 1 microM) of the benzodiazepine full agonist clonazepam did not significantly alter K+-evoked release of [3H]GABA but shifted the concentration-effect curve for muscimol to the left. This effect was blocked by the benzodiazepine antagonist flumazenil. By contrast, the benzodiazepine full inverse agonist methyl beta-carboline-3-carboxylate shifted the muscimol concentration-effect curve to the right and this too was blocked by flumazenil. The results suggest that the GABA autoreceptor in cortical slices from the rat is modulated by a benzodiazepine receptor.
Author List: Ennis C, Minchin M C
Publication Types: Journal Article
Substances mentioned in the article: Carbolines; Ligands; Receptors, GABA-A; 1-methyl-beta-carboline-3-carboxylic acid; Muscimol; Flumazenil; Clonazepam; Bicuculline;
Mesh terms: Animals; Bicuculline/pharmacology; Carbolines/pharmacology; Clonazepam/pharmacology; Flumazenil/pharmacology; Ligands; Male; Muscimol/pharmacology; Rats; Receptors, GABA-A/drug effects;