Characterization of the binding of two novel glycine site antagonists to cloned NMDA receptors: evidence for two pharmacological classes of antagonists

Abstract

1 The potency of two novel glycine site antagonists, GV150,526A and GV196,771A, was assessed by their ability to inhibit the binding of [ 3 H]-MDL105,519 to cell homogenates prepared from mammalian cells transfected with either NR1-1a, NR1-2a, NR1-1a/NR2A, NR1-1a/NR2B, NR1-1a/ NR2C or NR1-1a/NR2D NMDA receptor clones. 2 The inhibition constants (K i s) for GV150,526A displacement of [ 3 H]-MDL105,519 binding to either NR1-1a or NR1-2a expressed alone were not signi®cantly dierent and were best ®t by a onesite binding model. GV150,526A inhibition to NR1-1a/NR2 combinations was best ®t by a two-site model with the NR1-1a/NR2C having an approximate 2 ± 4 fold lower anity compared to other NR1-1a/NR2 receptors. 3 The K i s for GV196,771A displacement of [ 3 H]-MDL105,519 binding to NR1-1a, NR1-2a and all NR1-1a/NR2 combinations was best ®t by a two-site binding model. There was no signi®cant dierence between the K i s for the binding to NR1-1a and NR1-2a; NR1-1a/NR2A receptors had an approximate 4 fold lower anity for GV196,771A compared to other NR1-1a/NR2 combinations. 4 The K i s for both GV150,526A and GV196,771A for the inhibition of [ 3 H]-MDL105,519 binding to membranes prepared from adult rat forebrain were determined and compared to the values obtained for binding to cloned NMDA receptors. 5 The K i s for a series of glycine site ligands with diverse chemical structures were also determined for the inhibition of [ 3 H]-MDL105,519 binding to NR1-1a/NR2A receptors. L689,560 displayed similar binding characteristics to GV150,526A. 6 It is suggested that glycine site antagonists may be divided into two classes based on their ability to distinguish between NR1 and NR1/NR2 receptors with respect to binding curve characteristics.

Glycine bidirectionally regulates ischemic tolerance via different mechanisms including NR2A‐dependent CREB phosphorylation

“…L689‐560 (L689) is a highly selective NMDAR glycine co‐agonist binding site inhibitor (Chopra et al . ; Javitt et al . ; Yao et al .…”

“…We first identified whether NMDAR co-agonist site (site B) takes an effect on L-Gly-induced iLTP suppression. L689-560 (L689) is a highly selective NMDAR glycine co-agonist binding site inhibitor (Chopra et al 2000;Javitt et al 2005;Yao et al 2012). Bathing L689 (0.5 lM) (Yao et al 2012) eliminated the depression of i-LTP (n = 6, p < 0.001; Fig.…”

Rotenone-induced inner retinal degeneration via presynaptic activation of voltage-dependent sodium and L-type calcium channels in rats

“…8b) resulted in significant suppression of Nfl downregulation (P < 0.0001, vs rotenone or NMDA alone). The glycine-binding site antagonist gavestinel (15 nmol/eye) 23 slightly reduced rotenone-induced Nfl downregulation, whereas it significantly suppressed NMDA-induced Nfl downregulation (P < 0.0001, vs NMDA alone). Unexpectedly, the AMPA/kainate receptor antagonist 6-Cyano-7-nitroquinoxaline-2,3-dione (CNQX, 50 and 100 nmol/eye, respectively) substantially reduced Nfl downregulation induced by both rotenone and NMDA (P = 0.0005 and P < 0.0001, vs rotenone and NMDA alone, respectively).…”