Brain iNOS: current understanding and clinical implications.

Nitric oxide (NO) is a unique informational substance first identified as the endothelium-derived relaxing factor. It is generated by NO synthases and plays a prominent role in controlling a variety of organ functions in the cardiovascular, immune, reproductive and nervous systems. Inducible nitric oxide synthase (iNOS) is not normally present in the brain in youth but it can be detected in the brain after inflammatory, infectious or ischemic damage, as well as in the normal, aging brain. Brain iNOS seems to contribute to the pathophysiology of many diseases that involve the central nervous system, but the role of iNOS appears to go beyond tissue damage. Brain iNOS might be required for adequate repair following injury or damage. The effects of brain iNOS on the balance between damage and repair make this enzyme a promising therapeutic target in human disease.