Comparative studies on binding of 3 different ligands to the N-methyl-D-aspartate recognition domain in brain synaptic membranes treated with Triton X-100.
Treatment with a low concentration of Triton X-100 almost tripled the binding of [3H]D,L-(E)-2-amino-4-propyl-5-phosphono-3-pentenoic acid (CGP 39653), a novel competitive antagonist at an N-methyl-D-aspartate (NMDA)-sensitive subclass of brain excitatory amino acid receptors, in synaptic membranes of the rat brain. The binding linearly increased with increasing protein concentrations of up to 0.4 mg/ml and also increased in proportion to incubation time with a plateau within 60 min after the initiation of incubation at 2 degrees C in Triton-treated membranes. Elevation of incubation temperature from 2 degrees C to 30 degrees C resulted in a marked decrease in the binding at equilibrium by 80%, and a maximal level was obtained within 1 min after the initiation of incubation at 30 degrees C with a gradual decline of up to 10 min. Bound [3H]CGP 39653 was rapidly dissociated by the addition of excess unlabeled L-glutamic acid (Glu), and the time required to attain complete dissociation was 60 min at 2 degrees C and 1 min at 30 degrees C, respectively. Among several agonists and antagonists tested, Glu was the most potent displacer of [3H]CGP 39653 binding with progressively less potent displacement by D-2-amino-5-phosphonovaleric, (+-)-3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic (CPP), D-2-amino-7-phosphonoheptanoic, N-methyl-D-aspartic and N-methyl-L-aspartic acids.(ABSTRACT TRUNCATED AT 250 WORDS)
Zuo
P
P
Department of Pharmacology, Setsunan University, Osaka, Japan.
Ogita
K
K
Han
D
D
Yoneda
Y
Y
D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives / Q000378:metabolism / Q000493:pharmacokinetics; D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects*; D003902:Detergents / Q000494:pharmacology*; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D066298:In Vitro Techniques; D008297:Male; D017830:Octoxynol; D010879:Piperazines / Q000378:metabolism; D011092:Polyethylene Glycols / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism*
D003902:Detergents; D005971:Glutamates; D010879:Piperazines; D016194:Receptors, N-Methyl-D-Aspartate; C069052:CGP 39653; D018698:Glutamic Acid; D011092:Polyethylene Glycols; D015763:2-Amino-5-phosphonovalerate; D017830:Octoxynol; C050592:3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid