TARGETING NMDAR PORE DYSFUNCTION: MK-801–DERIVED BLOCKER PROTECTS GLUN2A-N615S MICE FROM AUDIOGENIC SEIZURES

N-methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels essential for synaptic plasticity, learning, and memory. When NMDAR function is disturbed, it can contribute to neurological and psychiatric disorders. Many de novo missense mutations affect the pore region, including the M2 loop that shapes ion flow and the physiological Mg2+ block. GluN2A-N615S (N615S) is a model pore variant with loss of Mg2+ block, and a knock-in (KI) mouse line is available.
We compared NMDAR antagonists in vivo, focusing on the novel MK-801–derived blocker K2060 and comparing it with ketamine and memantine. WT and N615S male mice received i.p. vehicle or drug and were tested 30 min later. We assessed acoustic startle response (ASR) and prepulse inhibition (PPI), and evaluated protection against audiogenic seizures (AGS). Locomotor activity was measured in the open field across increasing K2060 doses.
N615S mice showed ~5-fold lower ASR than WT and reduced PPI at higher prepulse intensities. At 5 mg/kg, none of the drugs changed ASR or PPI in either genotype. In the AGS assay, memantine, ketamine, and K2060 were protective at 5 mg/kg, but at 1 mg/kg only K2060 significantly reduced AGS versus vehicle. WT locomotion was unchanged up to 30 mg/kg K2060, whereas N615S mice showed reduced locomotion and stereotypy at 15 mg/kg.
Overall, these results indicate higher in vivo potency of K2060 than ketamine or memantine in the N615S model, while preserving startle and PPI at 5 mg/kg, supporting K2060 as a potent and well-tolerated tool compound for studies of NMDAR pore variants.