Structure–activity analysis of a novel NR2C/NR2D‐preferring NMDA receptor antagonist: 1‐(phenanthrene‐2‐carbonyl) piperazine‐2,3‐dicarboxylic acid

Abstract

piperazine-2,3-dicarboxylic acid (PBPD) is a moderate affinity, competitive N-methyl-D-aspartate (NMDA) receptor antagonist with an atypical pattern of selectivity among NMDA receptor 2 subunit (NR2) subunits. We now describe the activity of several derivatives of PBPD tested at both rat brain NMDA receptors using L-[ 3 H]-glutamate binding assays and at recombinant receptors expressed in Xenopus oocytes. 2 Substituting various branched ring structures for the biphenyl group of PBPD reduced NMDA receptor activity. However, substituting linearly arranged ring structures -fluorenone or phenanthrene groups -retained or enhanced activity. 3 Relative to PBPD, the phenanthrene derivative (2S*,3R*)-1-(phenanthrene-2-carbonyl)piperazine-2,3-dicarboxylic acid (PPDA) displayed a 30-to 78-fold increase in affinity for native NMDA receptors. At recombinant receptors, PPDA displayed a 16-fold (NR2B) to 94-fold (NR2C) increase in affinity over PBPD. 4 Replacement of the biphenyl group of PBPD with a 9-oxofluorene ring system resulted in small changes in receptor affinity and subtype selectivity. 5 2 0 -Bromo substitution on the biphenyl group of PBPD reduced antagonist affinity 3-to 5-fold at NR2A-, NR2B-and NR2D-containing receptors, but had little effect on NR2C-containing receptors. In contrast, 4 0 -fluoro substitution of the biphenyl ring of PBPD selectively increased NR2A affinity. 6 The aromatic rings of PBPD and PPDA increase antagonist affinity and appear to interact with a region of the NMDA receptor displaying subunit heterogeneity. PPDA is the most potent and selective NR2C/NR2D-preferring antagonist yet reported and thus may be useful in defining NR2C/ NR2D function and developing related antagonists with improved NMDA receptor subtype selectivity.

NR2D-containing NMDA receptors mediate tissue plasminogen activator-promoted neuronal excitotoxicity

“…PPDA was reported as a selective NR2D competitive antagonist at low concentrations, as we used, with an IC50 value of around 0.1 mM. 23,24,29 Although, PPDA was also reported as an antagonist of NR2C, in agreement with the absence of NR2C mRNA in our cultured cortical neurons, N2RC was only detected in the cerebellum, thalamus and olfactory bulb. 30 At low concentration, PPDA completely prevented the worsening effect of tPA on NMDA-induced neuronal death.…”

“…To address this question, we took advantage of the absence of NR2C subunits in our cell culture system ( Figure 3) and used phenanthrene derivative (2S*, 3R*)-1-(phenanthrene-2-carbonyl)piperazine-2,3-dicarboxylic acid (PPDA) at a concentration of 0.2 mM, earlier reported to inhibit NR2D-containing NMDAR. 23,24 In the presence of PPDA, the deleterious effect of tPA on NMDA-induced neuronal death was completely prevented (Figure 4a), supporting the actual involvement of NR2D-containing NMDAR. To further validate the hypothesis that NR2D subunit has an important function in NMDAR-mediated neurotoxicity, primary cultures of cortical neurons (12-14 DIV) were transiently transfected with Stealth RNA interference targeting NR2D.…”

Cocaine Enhances NMDA Receptor-Mediated Currents in Ventral Tegmental Area Cells via Dopamine D5Receptor-Dependent Redistribution of NMDA Receptors

“…7B). Finally, consistently with our Western blot analysis, when we tested the putative NR2A antagonist NVP-AAM077 (0.004 -4 M) (Auberson et al, 2002), we observed a similar dose-dependent inhibition of NMDAR-mediated responses both in control slices and in slices pretreated with cocaine (data not shown), although we need to point out that NVP-AAM077 might also bind NR2C-containing receptors (Feng et al, 2004). Together, our biochemical results suggest that acute cocaine causes increased expression of NR2B-containing NMDARs, specifically at the synaptic membrane, whereas our pharmacological results seem to suggest increased presence of functional NR1/NR2A/NR2B complexes, which are less sensitive to ifenprodil and Ro25-6981 antagonism, rather than dimeric NR1/NR2B NMDARs.…”

Contribution of extrasynapticN-methyl-d-aspartate and adenosine A1 receptors in the generation of dendritic glutamate-mediated plateau potentials

“…Given the sixfold greater sensitivity of NR2CD over NR2AB subunits to PPDA [21], these data suggest that NR2CD subunits are activated and contribute to the voltage and calcium waveforms of dendritic NMDA spikes.…”