Towards an Understanding of Integrative Brain Functions

Nitric oxide and carbon monoxide: parallel roles as neural messengers

Solomon H. Snyder*, Samie R. Jaffrey and Randa Zakhary
Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD 21205 (USA)

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Abstract
Nitric oxide is now appreciated to be a molecule with important signaling functions in the body. The purification and cloning of the first NO synthesizing enzyme, NO synthase (NOS), from brain has led to the characterization of the roles of NO in normal physiology and in pathogenic states. NO synthesis is regulated in a complex manner, involving the association of activitatory and inhibitory proteins. The body appears to use at least one other, highly related gas in a signaling function, carbon monoxide (CO). The enzyme responsible for CO biosynthesis in brain, heme oxygenase-2 (HO2), is rapidly regulated by neurotransmitter stimulation. The role for CO as neurotransmitter is suggested by the altered intestinal motility in mice harboring a genomic deletion of HO2.

*Corresponding author: sol_snyder@qmail.bs.jhu.edu

Brain Research Reviews 26 (1998) 167-175
Copyright © 1998 Elsevier Science B. V. All rights reserved.