Article date: 1987/11/24
PubMed ID: 2830119
Journal name: European journal of pharmacology (ISSN: 0014-2999)
The presence of autoreceptors for gamma-aminobutyric acid (GABA) in the CNS was reinvestigated using rat cortex synaptosomes prelabeled with [3H]GABA and exposed to GABA by superfusion in the presence of a new GABA uptake inhibitor, N-(4,4-diphenyl-3-butenyl)-nipecotic acid (SK&F 89976A). This compound itself did not increase the basal or the depolarization-evoked release of [3H]GABA. GABA reduced in a concentration-dependent way the release of [3H]GABA evoked by 15 mM K+. The effect was not antagonized by bicuculline, picrotoxin or by the new GABAA antagonist SR 95531. The GABAA agonist muscimol did not affect [3H]GABA release. This was reduced by (-)baclofen (but not by the (+) isomer) and the concentration-inhibition curve of (-)baclofen was superimposable on to that of GABA. Also the K+-evoked release of endogenous GABA was stereoselectively and concentration dependently inhibited by the (-) enantiomer of baclofen. It is concluded that the release of GABA from rat cortical nerve endings may be inhibited through the activation of autoreceptors which appear to belong to the GABAB type.
Author List: Pittaluga A, Asaro D, Pellegrini G, Raiteri M
Publication Types: Journal Article; Research Support, Non-U.S. Gov't
Substances mentioned in the article: Anticonvulsants; Nipecotic Acids; Pyridazines; Receptors, GABA-A; Picrotoxin; gamma-Aminobutyric Acid; N-(4,4-diphenyl-3-butenyl)nipecotic acid; gabazine; Baclofen; Potassium; Bicuculline;
Mesh terms: Animals; Anticonvulsants/pharmacology; Baclofen/pharmacology; Bicuculline/pharmacology; Cerebral Cortex/drug effects; In Vitro Techniques; Male; Median Eminence/drug effects; Nipecotic Acids/pharmacology; Picrotoxin/pharmacology; Potassium/pharmacology; Pyridazines/pharmacology; Rats; Rats, Inbred Strains; Receptors, GABA-A/metabolism; Synaptosomes/drug effects; gamma-Aminobutyric Acid/metabolism;