A specific quisqualate agonist inhibits kainate responses induced in Xenopus oocytes injected with rat brain RNA.
Electrophysiological recording was used to study non-N-methyl-D-aspartate (NMDA) excitatory amino acid (EAA) receptors after injection of rat brain ribonucleic acid (RNA) in Xenopus laevis oocytes. Quisqualate (QA) induced two types of responses, a smooth one and an oscillatory one. These responses are probably mediated by the ionotropic (QAi, a cationic channel) and the metabotropic (QAp, a newly discovered receptor coupled to phospholipase C) QA receptors respectively. alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) only induced a smooth inward current suggesting that it acts only on QAi. Kainate (KA) also induced a smooth inward current, the maximal KA response being 10-fold higher than the maximal AMPA. AMPA inhibited the KA response in a dose-dependent and competitive manner. Amongst various complex hypotheses the simplest to explain these results would be that KA and AMPA both activate the same receptor-channel complex, AMPA inducing a smaller response than KA.
Rassendren
F A
FA
CNRS Centre de Recherche de Biochimie Macromoléculaire, INSERM U 249, Montpellier, France.
Lory
P
P
Pin
J P
JP
Bockaert
J
J
Nargeot
J
J
D000818:Animals; D001921:Brain / Q000378:metabolism*; D003292:Convulsants / Q000494:pharmacology*; D005260:Female; D007051:Ibotenic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D007608:Kainic Acid / Q000494:pharmacology*; D007700:Kinetics; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010069:Oxadiazoles / Q000494:pharmacology*; D016318:Quisqualic Acid; D012313:RNA / Q000187:drug effects* / Q000235:genetics; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D014982:Xenopus laevis; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
D003292:Convulsants; D010069:Oxadiazoles; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D007051:Ibotenic Acid; D012313:RNA; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D016318:Quisqualic Acid; D007608:Kainic Acid