title: Interaction of allosteric ligands with GABAA receptors containing one, two, or three different subunits.
abstract: The presence of allosteric binding sites on recombinant GABAA receptors formed after transfection of human embryonic kidney (HEK) 293 cells with alpha 1-, beta 3-, or gamma 2-subunits, or with various combinations of these subunits, was systematically investigated. From all possible subunit combinations, high affinity [3H]muscimol binding sites were induced in cells transfected with alpha 1 beta 3- or alpha 1 beta 3 gamma 2-subunits only. GABAA receptor associated [3H]flunitrazepam binding sites were induced in cells after transfection with alpha 1 gamma 2- or alpha 1 beta 3, gamma 2-subunits, and [35S]r-butylbicyclophosphorothionate (TBPS) binding sites were found in cells transfected with beta 3-, beta 3 gamma 2-, alpha 1 beta 3-, or alpha 1 beta 3 gamma 2-subunits. Binding of [35S]TBPS could be inhibited by pentobarbital, etazolate, (+)-etomidate, alphaxalone, propofol, chlormethiazole, and 4'-chlorodiazepam (Ro 5-4864) with a potency which differed in cells transfected with beta 3-, beta 3 gamma 2-, alpha 1 beta 3-, or alpha 1 beta 3 gamma 2-subunits. Results obtained indicate that receptors with different subunit composition actually can be formed in HEK cells and exhibit distinct pharmacological properties.
authors.affiliation: Department of Biochemical Psychiatry, University Clinic for Psychiatry, Vienna, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Zezula
authors.forename: A
authors.initials: A
authors.lastname: Slany
authors.forename: W
authors.initials: W
authors.lastname: Sieghart
mesh_terms: D000495:Allosteric Site; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000493:pharmacokinetics; D002460:Cell Line; D003292:Convulsants / Q000493:pharmacokinetics; D005445:Flunitrazepam / Q000493:pharmacokinetics; D018755:GABA Agonists / Q000493:pharmacokinetics; D018757:GABA Modulators / Q000493:pharmacokinetics; D058787:GABA-A Receptor Antagonists; D006801:Humans; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D009118:Muscimol / Q000493:pharmacokinetics; D011869:Radioligand Assay; D011963:Receptors, GABA-A / Q000187:drug effects / Q000378:metabolism*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D003292:Convulsants; D018755:GABA Agonists; D018757:GABA Modulators; D058787:GABA-A Receptor Antagonists; D011963:Receptors, GABA-A; D009118:Muscimol; D005445:Flunitrazepam; C037476:tert-butylbicyclophosphorothionate