RT Journal Article
SR Electronic
T1 Inhibition of GluN2A-containing NMDA Receptors by 2-Naphthoic Acid
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP mol.113.087189
DO 10.1124/mol.113.087189
A1 Han Yu
A1 Gabriela K Popescu
YR 2013
UL http://molpharm.aspetjournals.org/content/early/2013/07/19/mol.113.087189.abstract
AB N-Methyl-D-aspartate (NMDA) receptors mediate excitatory synaptic transmission in central nervous system and play important roles in synaptic development and plasticity, but also mediate glutamate neurotoxicity. Recently, 2-naphthoic acid (NPA) and its derivatives have been identified as allosteric, noncompetitive NMDA receptor inhibitors. The selectivity of NPA derivatives among NMDA receptor subtypes was mapped structurally to the ligand-binding domain, and was proposed to be mediated by residues on the S1 segment. To delineate the kinetic mechanism by which NPA inhibits NMDA receptor activity, we examined its effects on the NMDA receptor gating reaction. Using whole-cell patch clamp on HEK293 cells expressing recombinant GluN1/GluN2A, we found that NPA has 50% inhibitory effect at 1.9 mM. Further, from one-channel current recordings, we found that 4 mM NPA caused a 62% decrease in open probability by decreasing mean open time 2.5-fold and by increasing mean closed time 2-fold. Kinetic modeling suggested that NPA binding stabilizes NMDA receptor closed states and increases the energy barriers toward open states, causing NMDA receptors to dwell longer in pre-open states along the activation pathway. The reaction mechanisms we derived provide quantitative insight into the inhibitory mechanism of NPA and help anticipate its effects on GluN1/GluN2A receptors during both physiological and pathological activation modalities.