Nitrous oxide acts directly at the mu opioid receptor.
Gillman
M A
MA
Lichtigfeld
F J
FJ
D006801:Humans; D009609:Nitrous Oxide / Q000494:pharmacology*; D011957:Receptors, Opioid / Q000187:drug effects*; D017450:Receptors, Opioid, mu
D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D009609:Nitrous Oxide