TY - JOUR

T1 - Molecular pharmacology of the AMPA agonist, (S)-2-amino-3-(3-hydroxy-5-phenyl-4-isoxazolyl)propionic acid [(S)-APPA] and the AMPA antagonist, (R)-APPA

AU - Ebert, B

AU - Madsen, U

AU - Lund, Trine Meldgaard

AU - Lenz, S M

AU - Krogsgaard-Larsen, P

PY - 1994/6

Y1 - 1994/6

N2 - The heterocyclic analogue of (S)-glutamic acid, (S)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid [(S)-AMPA] is a potent and selective AMPA receptor agonist, whereas the enantiomeric compound, (R)-AMPA, is virtually inactive. We have previously characterized (RS)-2-amino-3-(3-hydroxy-5-phenyl-4-isoxazolyl)propionic acid [(RS)-APPA] as a partial AMPA receptor agonist showing about 60% of the efficacy of (RS)-AMPA. This partial agonism produced by (RS)-APPA is, however, only apparent, since resolution of (RS)-APPA has now been shown to provide the full AMPA receptor agonist, (S)-APPA, whereas (R)-APPA is a non-N-methyl-D-aspartic acid (non-NMDA) receptor antagonist showing preferential AMPA blocking effects. In agreement with classical theories for competitive interaction between agonists and antagonists, the efficacy of depolarizations produced by (S)-APPA in the rat cortical wedge preparation was shown to be progressively reduced with increasing molar ratios of (R)-APPA/(S)-APPA. These compounds and the competitive antagonists (RS)-2-amino-3-(3-carboxymethoxy-5-methyl-4-isoxazolyl)propionic acid [(RS)-AMOA], 6-cyano-7-nitroquinoxalin-2,3-dione (CNQX) and 6-nitro-7-sulfamoylbenzo(f)quinoxalin-2,3-dione (NBQX) were also tested in [3H]AMPA and [3H]CNQX binding systems, the latter ligand being used in the absence or presence of thiocyanate ions. On the basis of these studies it is suggested that (RS)-AMPA and the AMPA agonist (S)-APPA interact with a high-affinity receptor conformation, whereas the competitive antagonists (RS)-AMOA and (R)-APPA, derived from these agonists, preferentially bind to a low-affinity AMPA receptor conformation.(ABSTRACT TRUNCATED AT 250 WORDS)

AB - The heterocyclic analogue of (S)-glutamic acid, (S)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid [(S)-AMPA] is a potent and selective AMPA receptor agonist, whereas the enantiomeric compound, (R)-AMPA, is virtually inactive. We have previously characterized (RS)-2-amino-3-(3-hydroxy-5-phenyl-4-isoxazolyl)propionic acid [(RS)-APPA] as a partial AMPA receptor agonist showing about 60% of the efficacy of (RS)-AMPA. This partial agonism produced by (RS)-APPA is, however, only apparent, since resolution of (RS)-APPA has now been shown to provide the full AMPA receptor agonist, (S)-APPA, whereas (R)-APPA is a non-N-methyl-D-aspartic acid (non-NMDA) receptor antagonist showing preferential AMPA blocking effects. In agreement with classical theories for competitive interaction between agonists and antagonists, the efficacy of depolarizations produced by (S)-APPA in the rat cortical wedge preparation was shown to be progressively reduced with increasing molar ratios of (R)-APPA/(S)-APPA. These compounds and the competitive antagonists (RS)-2-amino-3-(3-carboxymethoxy-5-methyl-4-isoxazolyl)propionic acid [(RS)-AMOA], 6-cyano-7-nitroquinoxalin-2,3-dione (CNQX) and 6-nitro-7-sulfamoylbenzo(f)quinoxalin-2,3-dione (NBQX) were also tested in [3H]AMPA and [3H]CNQX binding systems, the latter ligand being used in the absence or presence of thiocyanate ions. On the basis of these studies it is suggested that (RS)-AMPA and the AMPA agonist (S)-APPA interact with a high-affinity receptor conformation, whereas the competitive antagonists (RS)-AMOA and (R)-APPA, derived from these agonists, preferentially bind to a low-affinity AMPA receptor conformation.(ABSTRACT TRUNCATED AT 250 WORDS)

KW - 6-Cyano-7-nitroquinoxaline-2,3-dione

KW - Alanine

KW - Animals

KW - Brain

KW - Cell Membrane

KW - Cerebral Cortex

KW - Evoked Potentials

KW - Isoxazoles

KW - Male

KW - Organ Specificity

KW - Radioligand Assay

KW - Rats

KW - Rats, Wistar

KW - Receptors, AMPA

KW - Stereoisomerism

KW - Structure-Activity Relationship

KW - alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid

M3 - Journal article

C2 - 7526921

VL - 24

SP - 507

EP - 515

JO - Neurochemistry International

JF - Neurochemistry International

SN - 0197-0186

IS - 6

ER -