title: Novel positive allosteric modulators of GABAA receptors with anesthetic activity.
abstract: GABAA receptors are the main inhibitory neurotransmitter receptors in the brain and are targets for numerous clinically important drugs such as benzodiazepines, anxiolytics and anesthetics. We previously identified novel ligands of the classical benzodiazepine binding pocket in α1β2γ2 GABAA receptors using an experiment-guided virtual screening (EGVS) method. This screen also identified novel ligands for intramembrane low affinity diazepam site(s). In the current study we have further characterized compounds 31 and 132 identified with EGVS as well as 4-O-methylhonokiol. We investigated the site of action of these compounds in α1β2γ2 GABAA receptors expressed in Xenopus laevis oocytes using voltage-clamp electrophysiology combined with a benzodiazepine site antagonist and transmembrane domain mutations. All three compounds act mainly through the two β+/α- subunit transmembrane interfaces of the GABAA receptors. We then used concatenated receptors to dissect the involvement of individual β+/α- interfaces. We further demonstrated that these compounds have anesthetic activity in a small aquatic animal model, Xenopus laevis tadpoles. The newly identified compounds may serve as scaffolds for the development of novel anesthetics.
authors.affiliation: Institute of Biochemistry and Molecular Medicine, University of Bern, CH-3012 Bern, Switzerland.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Maldifassi
authors.affiliation: Institute of Biochemistry and Molecular Medicine, University of Bern, CH-3012 Bern, Switzerland.
authors.forename: Roland
authors.initials: R
authors.lastname: Baur
authors.affiliation: Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, 02114 Massachusetts.
authors.forename: David
authors.initials: D
authors.lastname: Pierce
authors.affiliation: Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, 02114 Massachusetts.
authors.forename: Anahita
authors.initials: A
authors.lastname: Nourmahnad
authors.affiliation: Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, 02114 Massachusetts.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Forman
authors.affiliation: Institute of Biochemistry and Molecular Medicine, University of Bern, CH-3012 Bern, Switzerland.
authors.forename: Erwin
authors.initials: E
authors.lastname: Sigel
mesh_terms: D000494:Allosteric Regulation / Q000187:drug effects; D000777:Anesthetics / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D001569:Benzodiazepines / Q000737:chemistry* / Q000494:pharmacology; D003198:Computer Simulation; D004353:Drug Evaluation, Preclinical; D005442:Flumazenil / Q000737:chemistry / Q000494:pharmacology; D008024:Ligands; D015394:Molecular Structure; D018408:Patch-Clamp Techniques; D011963:Receptors, GABA-A / Q000378:metabolism*; D029867:Xenopus Proteins / Q000378:metabolism; D014982:Xenopus laevis / Q000378:metabolism*
chemical_list: D000777:Anesthetics; D008024:Ligands; D011963:Receptors, GABA-A; D029867:Xenopus Proteins; D001569:Benzodiazepines; D005442:Flumazenil