Carbon monoxide: a novel neural messenger or putative neurotransmitter?

The novel data indicating the role of carbon monoxide as an eventual putative neurotransmitter are discussed. The perspectives of further studies are delineated. Actually following scarce points suggest that carbon monoxide (CO) my be eventually neurotransmitter: an uneven distribution in the nervous system of heme oxygenase, which produces CO; the generation of long term potentiation in hippocampus; possible mediation of release of hypothalamic factors; eventual signalling role of CO in immune system.