Nitric Oxide (NO) Synthase Inhibitors: Potential Candidates for the Treatment of Anxiety Disorders?

Close to 19% of the world population suffers from anxiety. Current medications for this chronic mental disorder have improved treatment over the last half century or more, but the newer anxiolytics have proved disappointing, and enormous challenges remain. Nitric oxide (NO), an intra- and inter-cellular messenger in the brain, is involved in the pathogenesis of anxiety. In particular, excessive NO production might contribute to its pathology. This implies that it might be useful to reduce nitrergic activity; therefore, molecules aiming to downregulate NO production such as NO synthase inhibitors (NOSIs) might be candidates. Here, it was intended to critically review advances in research on these emerging molecules for the treatment of anxiety disorders. Current assessment indicates that, although NOSIs are implicated in anxiety, their potential anti-anxiety action remains to be established.