Inhibition of alpha-subunit glycine receptors by quinoxalines.
Quinoxalines are widely used compounds in electrophysiological studies to separate excitatory and inhibitory neurotransmission mediated by the strychnine-insensitive and strychnine-sensitive glycine receptor (NMDA, GlyR), respectively. We report here, that the quinoxaline NBQX is a potent antagonist of homo-oligomeric alpha1- and alpha2-subunit glycine receptors expressed in Xenopus laevis oocytes. NBQX elicited half-maximal inhibition of glycine evoked currents at a concentration of about 5 microM. DNQX and CNQX were found to be 5-fold and 20-fold less efficient than NBQX. At oocytes expressing alpha1beta2 subunit GABAA receptors the quinoxalines tested showed no significant inhibition of GABA responses up to a concentration of 100 microM. Our data indicates that these quinoxalines applied at concentrations sufficient to block NMDA receptor also attenuate GlyR responses.
Meier
Jochen
J
Johannes-Mueller-Institute of Physiology, Campus Charité, Humboldt-University Berlin, Tucholskystrasse 2, 10117 Berlin, Germany.
Schmieden
Volker
V
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000465:Algorithms; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D058787:GABA-A Receptor Antagonists; D006801:Humans; D009865:Oocytes / Q000378:metabolism; D011810:Quinoxalines / Q000494:pharmacology*; D018009:Receptors, Glycine / Q000819:agonists / Q000037:antagonists & inhibitors*; D014982:Xenopus laevis
D058787:GABA-A Receptor Antagonists; D011810:Quinoxalines; D018009:Receptors, Glycine; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione