Coupling between agonist and chloride ionophore sites of the GABA(A) receptor: agonist/antagonist efficacy of 4-PIOL.

Article date: 2000/12/8

PubMed ID: 11108817

Journal name: European journal of pharmacology (ISSN: 0014-2999)


Eight gamma-aminobutyric acid (GABA) mimetics were tested on their ability to differentiate native GABA(A) receptor subtypes present in various rat brain regions. In rat brain cryostat sections, little regional variations by the agonistic actions of muscimol, thiomuscimol, 4,5,6,7-tetrahydroisoazolo(5,4-c)pyridin-3-ol, piperidine-4-sulphonic acid, taurine and beta-alanine on [35S]t-butylbicyclophosphorothionate ([35S]TBPS) binding to GABA(A) receptor channels were found. They were very similar to those found for GABA itself and indicated no direct correlation with single subunit distributions for any of these compounds. Only the low-efficacy GABA mimetic 5-(4-piperidyl)isoxazol-3-ol (4-PIOL) acted like a weak partial agonist or antagonist depending on the brain area. As the cerebellar granule cell layer was relatively insensitive to both modes of action, we tested 4-PIOL in recombinant alpha1beta2gamma2 (widespread major subtype) and alpha6beta2gamma2 (cerebellar granule cell restricted) receptors where it had different effects on GABA-modulated [35S]TBPS binding and on electrophysiological responses. 4-PIOL may thus serve as a potential lead for receptor subtype selective compounds.

This document is available from: http://directlinks.cc/files/muscimol/11108817.pdf

Author List: Rabe H, Picard R, Uusi-Oukari M, Hevers W, Lüddens H, Korpi E R

Publication Types: Journal Article; Research Support, Non-U.S. Gov't

Substances mentioned in the article: Bridged Bicyclo Compounds, Heterocyclic; GABA Agonists; Ionophores; Isoxazoles; Ligands; Piperidines; Receptors, GABA-A; 5-(4-piperidyl)isoxazol-3-ol; tert-butylbicyclophosphorothionate;

Mesh terms: Animals; Brain/metabolism; Bridged Bicyclo Compounds, Heterocyclic/metabolism; Cell Line; GABA Agonists/metabolism; Humans; Ionophores/metabolism; Isoxazoles/metabolism; Ligands; Male; Piperidines/metabolism; Rats; Rats, Wistar; Receptors, GABA-A/metabolism;

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