The effect of corticosteroids on serum and cerebrospinal fluid nitric oxide levels in multiple sclerosis

Multiple sclerosis is a disease characterized by perivascular infiltrates a nd demyelination of the white matter in the central nervous system. In this study, we compared the serum and cerebrospinal fluid nitric oxide levels b efore and after methylprednisolone therapy, and during remission period, an d investigated the relationship of nitric oxide to the activity of multiple sclerosis. Cerebrospinal fluid and serum nitric oxide levels were measured blind as nitrite plus nitrate, using the nitrate reductase and Griess reac tion method in 20 patients with multiple sclerosis before and after cortico steroid therapy, and during remission period, and in 20 control subjects. M ean cerebrospinal fluid and serum nitric oxide levels were highest in the p retreatment group and lowest in the control group. There was no correlation with nitric oxide levels in these two groups. Although corticosteroid ther apy did not have any great effect on Expanded Disability Status Scales, it led to a decrease in nitric oxide levels. The possible cause of this might be the inhibition of nitric oxide synthesis by methylprednisolone, or a dec rease in multiple sclerosis activity. We conclude that serum or cerebrospin al fluid nitric oxide levels do not reflect the activity in multiple sclero sis.