title: TCN 201 selectively blocks GluN2A-containing NMDARs in a GluN1 co-agonist dependent but non-competitive manner.
abstract: Antagonists that are sufficiently selective to preferentially block GluN2A-containing N-methyl-d-aspartate receptors (NMDARs) over GluN2B-containing NMDARs are few in number. In this study we describe a pharmacological characterization of 3-chloro-4-fluoro-N-[4-[[2-(phenylcarbonyl)hydrazino]carbonyl]benzyl]benzenesulphonamide (TCN 201), a sulphonamide derivative, that was recently identified from a high-throughput screen as a potential GluN2A-selective antagonist. Using two-electrode voltage-clamp (TEVC) recordings of NMDAR currents from Xenopus laevis oocytes expressing either GluN1/GluN2A or GluN1/GluN2B NMDARs we demonstrate the selective antagonism by TCN 201 of GluN2A-containing NMDARs. The degree of inhibition produced by TCN 201 is dependent on the concentration of the GluN1-site co-agonist, glycine (or D-serine), and is independent of the glutamate concentration. This GluN1 agonist-dependency is similar to that observed for a related GluN2A-selective antagonist, N-(cyclohexylmethyl)-2-[{5-[(phenylmethyl)amino]-1,3,4-thiadiazol-2-yl}thio]acetamide (TCN 213). Schild analysis of TCN 201 antagonism indicates that it acts in a non-competitive manner but its equilibrium constant at GluN1/GluN2A NMDARs indicates TCN 201 is around 30-times more potent than TCN 213. In cortical neurones TCN 201 shows only modest antagonism of NMDAR-mediated currents recorded from young (DIV 9-10) neurones where GluN2B expression predominates. In older cultures (DIV 15-18) or in cultures where GluN2A subunits have been over-expressed TCN 201 gives a strong block that is negatively correlated with the degree of block produced by the GluN2B-selective antagonist, ifenprodil. Nevertheless, while TCN 201 is a potent antagonist it must be borne in mind that its ability to block GluN2A-containing NMDARs is dependent on the GluN1-agonist concentration and is limited by its low solubility.
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK.
authors.forename: S
authors.initials: S
authors.lastname: Edman
authors.forename: S
authors.initials: S
authors.lastname: McKay
authors.forename: L J
authors.initials: LJ
authors.lastname: Macdonald
authors.forename: M
authors.initials: M
authors.lastname: Samadi
authors.forename: M R
authors.initials: MR
authors.lastname: Livesey
authors.forename: G E
authors.initials: GE
authors.lastname: Hardingham
authors.forename: D J A
authors.initials: DJ
authors.lastname: Wyllie
mesh_terms: D000465:Algorithms; D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology; D055724:Electrophysiological Phenomena; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D005998:Glycine / Q000378:metabolism / Q000494:pharmacology; D009474:Neurons / Q000502:physiology; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010957:Plasmids / Q000235:genetics; D018075:RNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D018092:Kainic Acid Receptors / Q000819:agonists* / Q000235:genetics; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists* / Q000037:antagonists & inhibitors* / Q000235:genetics; D012694:Serine / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology*; D014162:Transfection; D014982:Xenopus laevis; D006834:Hydrazines; D000096926:Benzenesulfonamides
chemical_list: D018691:Excitatory Amino Acid Antagonists; D018698:Glutamic Acid; D005998:Glycine; D018075:RNA, Complementary; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate; D012694:Serine; D013449:Sulfonamides; C574512:TCN 201; D006834:Hydrazines; D000096926:Benzenesulfonamides