Blocking NMDA receptors with drugs like PCP and ketamine causes psychosis-like symptoms in humans and hyperlocomotion in rodents. Mice lacking the GluN2D subunit of the NMDA receptor show reduced hyperlocomotion in response to these drugs, suggesting this subunit is key for that effect. This study tested male and female mice lacking GluN2D and found they also had blunted locomotor responses to PCP, S-ketamine, and R-norketamine, in both sexes. These knockout mice showed an anxious baseline, and the drugs had anxiolytic effects that varied by sex and genotype. S-ketamine disrupted spatial memory in females and object recognition in both sexes, regardless of genotype. The GluN2D subunit mediates sex-specific and drug-specific behavioral effects of NMDA receptor antagonists.
Working memory relies on synchronized brain oscillations involving interactions between pyramidal cells and GABAergic interneurons. NMDA receptor antagonists affect both oscillations and memory, but the link was unclear. In mice performing a touchscreen working memory task, phencyclidine (PCP) disrupted accuracy in wildtype but not GluN2D-knockout mice, indicating PCP's action requires the GluN2D subunit. MK-801, (S)-ketamine, and (R)-ketamine impaired accuracy in both genotypes. PCP increased baseline gamma power in the hippocampus only in wildtypes, while all drugs increased prefrontal gamma power. Low gamma activity during the memory maintenance phase rose when mice answered correctly, and this task-related increase was disrupted by all drugs. The GluN2D subunit mediates PCP's effects on hippocampal gamma and working memory.