2-BFI protects against ischemic stroke by selectively acting on NR2B-containing NMDA receptors

Abstract NMDA receptors play opposing roles in the pathology of ischemic stroke, depending on whether they contain the NR2A or NR2B subunit. Building on our previous finding that the compound 2-(benzofuran-2-yl)-2-imidazoline (2-BFI) can inhibit NMDA receptor currents and exert neuroprotective effects during ischemic stroke, here we examined whether 2-BFI acts on NR2A- and/or NR2B-containing NMDARs. Whole-cell patch-clamp results showed that 2-BFI dose-dependently inhibited NR2A-containing NMDARs currents (IC 50 = 238.6µM) and NR2B-containing NMDARs currents (IC 50 = 18.47µM). Experiments in HEK293 cells expressing exogenous receptor subunits showed that 2-BFI exhibited a significantly higher affinity towards NR2B-containing NMDARs as compared to NR2A-containing ones. Administering both 2-BFI and an inhibitor of the NR2A subunit NVP-AAM077 to rats with transient middle cerebral artery occlusion(tMCAO) led to less severe cerebral ischemic injury than administering only NVP-AAM077. 2-BFI significantly altered the expression of proteins downstream of NR2B-containing NMDA receptor, but not of proteins downstream of NR2A-containing receptor. These results suggest that 2-BFI may exert neuroprotective effects in ischemic stroke by preferentially inhibiting NR2B-containing NMDA receptors.