Modulation of Adult Neurogenesis by the Nitric Oxide System

Nitric oxide (NO) is a gaseous free radical that acts as a second messenger having an important biological role in intercellular communication and in intracellular signaling in many tissues, including the brain (reviewed by [1]). NO is synthesized by the nitric oxide synthase (NOS) family of enzymes, which convert L-arginine to L-citrulline and NO. There are three different isoforms of NOS: a) neuronal NOS (nNOS or NOS I), b) endothelial NOS (eNOS or NOS III), and c) inducible NOS (iNOS or NOS II) (reviewed by [2]). Different members of the NOS family control different functions of NO (reviewed by [1]).