Search

Nitric oxide (NO) is a messenger that participates in several physiological and pathophysiological processes. It is produced by several cell types and may act on almost all of them. In living systems, its main reactions are interaction with oxyhemoglobin, with metals in proteins and its degradation by superoxide anion. It is part of signaling cascades by activating guanylate ciclase. In the central nervous system, it participates in the coupling of brain activity and blood flow, to guide nerve endings grow, to regulate neuronal migration and survival as well as glial cell differentiation and neurotransmitter release. NO is produced by NO synthase (NOS), of which three isoforms exist. The brain is the organ with the highest NOS activity. Glutamate is the main neurotransmitter associated with NO. Both toxic and protective effects are associated with NO. NO toxicity was known before its physiological function, it is associated with several pathologies including depression, neurodegenerative diseases, migraine, epilepsy and multiple sclerosis. Those pathologies involve the great amount of processes mediated by NO, all the cell types that produced it and all the cell that are responsive to this messenger. [ABSTRACT FROM AUTHOR]