Studies on the subtype selectivity of CP-101,606: evidence for two classes of NR2B-selective NMDA receptor antagonists.
The subtype-selectivity of racemic [(3)H]CP-101,606, a novel high-affinity NMDA receptor radioligand was determined using defined recombinant NMDA receptor subunits expressed in HEK 293 cells. [(3)H]CP-101,606 binds to adult rodent forebrain and NR1/NR2B receptors expressed in HEK 293 cells with K(D)=4.2 nM and 6.0 nM, respectively. In contrast, no high affinity specific binding was detected to NR1, NR2A, NR2B subunits expressed alone or NR1/NR2A receptors. HEK 293 cells were transfected with NR1, NR2A and NR2B receptor subunits and complexes comprising all three subunits were isolated by anti-NR2A immunoaffinity chromatography. Based on immunoblotting with subunit-selective antibodies, the immunopurified material contained all three NMDA receptor subunit polypeptides. However, in contrast to parallel studies in which high affinity [(3)H]Ro-25,6981 binding activity was observed, no high affinity [(3)H]CP-101,606 binding sites were detected to the immunopurified material. This study provides further evidence for two distinct classes of NR2B-directed NMDA receptor antagonists, one which binds with high affinity irrespective whether another NR2 subunit type is present (Ro-25,6981) and a second class which is affected significantly by the presence of another NR2 subunit type within the receptor complex, exemplified by CP-101,606.
Chazot
Paul L
PL
Institute of Pharmacy, Chemistry and Biomedical Sciences, University of Sunderland, Sunderland, Tyne and Wear SR2 3SD, UK. paul.chazot@sunderland.ac.uk
Lawrence
Stephanie
S
Thompson
Christopher L
CL
D000818:Animals; D018691:Excitatory Amino Acid Antagonists / Q000378:metabolism*; D006801:Humans; D010880:Piperidines / Q000378:metabolism*; D016548:Prosencephalon / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*
D018691:Excitatory Amino Acid Antagonists; C409466:NR1 NMDA receptor; C120997:NR2A NMDA receptor; C121001:NR2B NMDA receptor; D010880:Piperidines; D016194:Receptors, N-Methyl-D-Aspartate; C095106:traxoprodil mesylate