RESUMO
Nitric oxide is a signaling molecule that has various roles under normal conditions, notably in relation to vasodilation, neuronal function, and immune responses. Additionally, it has been implicated in some pathological states including multiple sclerosis. Multiple sclerosis is characterized by chronic inflammation and oligodendrocyte and axonal damage and ultimately death of neurons. The precise role of nitric oxide in pathogenesis is confounded by its opposing beneficial and deleterious effects. With respect to multiple sclerosis, increased nitric oxide metabolites have been well documented in the cerebrospinal fluid of patients. Reports on changes in the concentration of nitric oxide in the serum of patients have been inconsistent. Here, we report statistically significant increases in the concentrations of nitric oxide metabolites in the serum of multiple sclerosis patients not under medications from two subpopulations in Iran, supporting contentions that disease status does correlate with nitric oxide levels in this easily accessible body fluid. However, the tightness of the correlation appears to be insufficient to allow it to be used as an independent surrogate for assessment of disease status.