Discovery of Dihydropyrrolo[1,2-<i>a</i>]pyrazin-3(4<i>H</i>)-one-Based Second-Generation GluN2C- and GluN2D-Selective Positive Allosteric Modulators (PAMs) of the <i>N</i>-Methyl-<scp>d</scp>-Aspartate (NMDA) Receptor
Matthew P. Epplin, Ayush Mohan, Lynnea D. Harris, Zongjian Zhu, Katie L. Strong, John Bacsa, Phuong Le, David S. Menaldino, Stephen F. Traynelis, Dennis C. Liotta
Abstract
The N-methyl-d-aspartate receptor (NMDAR) is an ion channel that mediates the slow, Ca2+-permeable component of glutamatergic synaptic transmission in the central nervous system (CNS). NMDARs are known to play a significant role in basic neurological functions, and their dysfunction has been implicated in several CNS disorders. Herein, we report the discovery of second-generation GluN2C/D-selective NMDAR-positive allosteric modulators (PAMs) with a dihydropyrrolo[1,2-a]pyrazin-3(4H)-one core. The prototype, R-(+)-EU-1180-453, exhibits log unit improvements in the concentration needed to double receptor response, lipophilic efficiency, and aqueous solubility, and lowers cLogP by one log unit compared to the first-generation prototype CIQ. Additionally, R-(+)-EU-1180-453 was found to increase glutamate potency 2-fold, increase the response to maximally effective concentration of agonist 4-fold, and the racemate is brain-penetrant. These compounds are useful second-generation in vitro tools and a promising step toward in vivo tools for the study of positive modulation of GluN2C- and GluN2D-containing NMDA receptors.