AMPA receptor antagonists, GYKI 52466 and NBQX, do not block the induction of long-term potentiation at therapeutically relevant concentrations

• Published in: Brain research bulletin 2000-08, Vol.52 (6), p.511-517
• Main Authors: Kapus, Gábor, Székely, József I, Durand, Jacques, Ruiz, Arnaud, Tarnawa, István
• Format: Article
• Language: English
• Subjects: AMPA receptors; Animals; Anti-Anxiety Agents - pharmacology; Benzodiazepines; Biological and medical sciences; Central nervous system; Dose-Response Relationship, Drug; Electrophysiology; Epilepsy - drug therapy; Epilepsy - physiopathology; Excitatory Amino Acid Antagonists - pharmacology; Excitatory Postsynaptic Potentials - drug effects; Excitatory Postsynaptic Potentials - physiology; Fundamental and applied biological sciences. Psychology; GYKI 52466; Hippocampus; Hippocampus - cytology; Hippocampus - drug effects; Hippocampus - metabolism; Long-term potentiation; Long-Term Potentiation - drug effects; Long-Term Potentiation - physiology; Male; Memory - drug effects; Memory - physiology; NBQX; Neurodegenerative Diseases - drug therapy; Neurodegenerative Diseases - physiopathology; Neurons - cytology; Neurons - drug effects; Neurons - metabolism; Organ Culture Techniques; Quinoxalines - pharmacology; Rats; Rats, Sprague-Dawley; Receptors, AMPA - antagonists & inhibitors; Receptors, AMPA - drug effects; Receptors, AMPA - metabolism; Vertebrates: nervous system and sense organs
• ISSN: 0361-9230; 1873-2747
• DOI: 10.1016/S0361-9230(00)00288-4

The involvement of α-amino-3-hydroxy-5-methylizoxazole-4-propionic acid (AMPA) receptors in induction of long-term potentiation (LTP) was examined in rat hippocampal slice preparation. Using conventional extracellular recording, excitatory postsynaptic potentials (EPSPs) and population action potentials (PSs), evoked by low-frequency stimulation of the Schaffer collateral-commissural fibres, were recorded in the CA1 region. The effects of a competitive AMPA receptor antagonist, 6-nitro-7-sulfamoylbenzo(f)quinoxaline-2,3-dione (NBQX), and that of a non-competitive blocker, 1-(4-aminophenyl)-4-methyl-7,8-methylendioxy-5H-2,3-benzodiazepine (GYKI 52466) have been examined. 0.25–0.5 μM of NBQX and 20–40 μM of GYKI 52466 did not suppress the induction of LTP. LTP was attenuated only at the highest concentrations tested (1 μM NBQX or 80 μM GYKI 52466). These in vitro concentrations, however, exceed the brain levels needed for in vivo anticonvulsant action. Furthermore, even at the highest concentrations both compounds suppressed only the expression but not the induction of LTP. Namely after their washout LTP reappeared. Thus, at pharmacologically relevant concentrations these AMPA receptor antagonists apparently do not suppress LTP, a cellular mechanism underlying memory formation. These experiments suggest that in clinical practice AMPA receptor blockade may have some advantage over N-methyl-D-aspartate receptor antagonism, which is accompanied by severe memory impairment.