Nitrous oxide (laughing gas) is an NMDA antagonist, neuroprotectant and neurotoxin. - Jevtovic-Thodorovic,V.; Todorovic,S.M.; Mennerick,S.; Powell,S.; Dikranian,K.; Benshoff,N.; Zorumski,C.F.; Olney,J.W. (Nat Med, 1998)