Ketoconazole inhibits lipopolysaccharide-induced activation of the nitric oxide synthase gene in the murine macrophage cell line J774

The aim of this study was to determine whether ketoconazole can affect the expression of the nitric oxide (NO) synthase gene in the murine macrophage cell line J774, The inducible enzyme (i-NOS) is activated in murine macroph ages by LPS and cytokines, Exposure of the J774 cell line to ketoconazole f or 24 h did not induce any NO release. Cells preincubated with ketoconazole and treated with LPS showed a significant decrease in nitrite levels in th e culture medium, compared with controls (cells treated with LPS alone), Th e addition of 1 mM N-monomethyl-L-arginine (L-NMMA), a structural analogue of arginine, reduced nitrite levels by about 88 +/- 9.2% in cells treated w ith LPS alone, whereas in those treated with ketoconazole + LPS, the levels were comparable to the baseline values detected in control cells. Northern blotting, used to assess i-NOS mRNA expression in the J774 cells, showed t hat ketoconazole reduced the LPS-induced increase in i-NOS mRNA activation by about 50%, These results support another mechanism for the antiinflammat ory effect of ketoconazole (i.e. reduction in i-NOS gene expression and con sequently inhibition of reactive radical NO production), that may explain t he antierythema and antiedema action of this compound, besides its antimyco tic effects.