GluN2A-NMDA receptor inhibition disinhibits the prefrontal cortex, reduces forced swim immobility, and impairs sensorimotor gating
Abstract
Recent investigations into the rapid antidepressant effects of ketamine, along with studies on schizophrenia-related susceptibility genes, have highlighted the GluN2A subunit as a critical regulator of both emotion and cognition. However, the specific impacts of acute pharmacological inhibition of GluN2A-containing NMDA receptors on brain microcircuits and the subsequent behavioral consequences remain poorly understood. In this study, we first examined the effects of MPX-004, a selective GluN2A NMDA receptor inhibitor, on behavior within the dorsomedial prefrontal cortex (dmPFC). Local administration of MPX-004 in the dmPFC led to a reduced immobility duration in the forced swim test, an acute antidepressant-like effect, impairments in sensorimotor gating, and a schizophrenia-like phenotype. In vivo multiple-channel recordings and c-Fos staining revealed that MPX-004 decreases the activity of parvalbumin-expressing interneurons (PV-INs) and increases the activity of pyramidal neurons (PYNs). In vivo patch-clamp recordings further confirmed that PV-IN inactivation leads to an elevated PYN firing rate in the PFC. In vitro whole-cell recordings demonstrated that PV-INs receive stronger excitatory synaptic input and respond more robustly to presynaptic stimulation than do somatostatin-expressing interneurons (SST-INs) and PYNs, rendering them susceptible to GluN2A inhibition. Finally, the specific knockdown of GluN2A in prefrontal PV-INs abolished the behavioral effects of MPX-004, underscoring a critical role of the GluN2A-mediated modulation of PV-INs in these phenotypes. Together, these findings reveal that PV-INs are particularly vulnerable to GluN2A inhibition, leading to disinhibition of prefrontal circuits and resulting in both antidepressant-like and schizophrenia-like behaviors.
Keywords:
NMDA receptor; psychiatry; prefrontal cortex; microcircuit; disinhibition