NOS1 and major depressive disorder: This effect was not induced by 7-nitroindazole, a specific neuronal NOS inhibitor, suggesting that it is not dependent on neuronal NOS.(7) The interaction between the nitrergic system and anxiety- and depression-like behaviors is possibly dose-dependent since low L-arginine and L-NAME doses increased the antidepressant effect of scopolamine in the FST.(44,45) Notably, the antidepressant effect of mecamylamine may be potentiated by the co-administration of low L-NAME or L-arginine doses.