Nitric oxide and nitric oxide synthase in Huntington's disease

Nitric oxide (NO) is a biologically active inorganic molecule produced when the semiessential amino acid I-arginine is converted to I-citrulline and N O via the enzyme nitric oxide synthase (NOS). NO is known to be involved in the regulation of many physiological processes, such as control of blood f low, platelet adhesion, endocrine function, neurotransmission, neuromodulat ion, and inflammation, to name only a few. During neuropathological conditi ons, the production of NO can be either protective or toxic, dependent on t he stage of the disease, the isoforms of NOS involved, and the initial path ological event. This paper reviews the properties of NO and NOS and the pat hophysiology of Huntington's disease (HD). It discusses ways in which NO an d NOS may interact with the protein product of HD and reviews data implicat ing NOS in the neuropathology of HD. This is followed by a synthesis of cur rent information regarding how NO/NOS may contribute to HD-related patholog y and identification of areas for potential future research. J. Neurosci. R es. 64:99-107, 2001. (C) 2001 Wiley-Liss, Inc.