Nitrous oxide modulates cortical activity, wake-sleep oscillations, and produces antidepressant-like effects in mice
Emerging evidence suggests that nitrous oxide (N2O), a gaseous NMDA receptor antagonist and dissociative anesthetic, exerts rapid antidepressant effects akin to subanesthetic ketamine. However, its cellular, molecular, and behavioral effects remain poorly understood. Using in vivo two-photon imaging through cortical microprisms, we demonstrate that 50% N2O/O2 rapidly increases neuronal calcium activity in the mouse medial prefrontal cortex (mPFC). This was corroborated by elevated c-Fos expression at both protein and mRNA levels in mPFC lysates. Cortical EEG recordings revealed that N2O increased subsequent wake-associated gamma oscillations and enhanced slow-wave activity during sleep, suggestive of cortical activation and synaptic potentiation. In a chronic corticosterone stress model, N2O elicited antidepressant-like behavioral effects in several, though not all, domains. Together, these findings indicate that a single treatment with N2O rapidly enhances cortical activity, modulates sleep and wake EEG oscillations, and produces antidepressant-like effects, paralleling key actions associated with subanesthetic ketamine.