Effect of dexamethasone on nitric oxide (NO.) production by cultured astrocytes.

Glial cell-derived nitric oxide (NO.) and its regulation has significant implications for central nervous system pathophysiology. The aim of the present study was to determine the production of NO. by cultured rat astrocytes and peritoneal macrophages, and its regulation by glucocorticoids. Results corroborate the presence of both constitutive and induced NO. synthase (cNOS and iNOS) in astrocytes, while macrophages express only the inducible isoform. Dexamethasone was able to decrease NO. synthesis produced by induction of iNOS in macrophage and astrocyte phagocytosis, but not the NO. produced by the cNOS spontaneously expressed in cultured astrocytes.