Nitric Oxide Gas (aka Laughing Gas) kills neurons. John Hopkins has a Dr. Ted Dawson who studied Nitric oxide in neuronal injury in stroke and excitotoxicity and elucidated the molecular mechanisms by which nitric oxide and poly (ADP-ribose) polymerase kills neurons. His studies of nitric oxide led to major insights into the neurotransmitter functions of this gaseous messenger molecule. He co-discovered the neurotrophic properties on non-immunosuppressant immunophilin ligands.

Just adding more info to the mix.

Vicky