Effect of Dexamethasone and Nigella sativa on Inducible Nitric Oxide Synthase in the Lungs of a Murine Model of Allergic Asthma

The aim of this study was to investigate the effects of Nigella sativa (NS) fixed oil in comparison to dexamethasone (Dex) on inducible nitric oxide synthase (iNOS), peripheral blood eosinophils (PBE), allergen specific serum IgG1 and interleukins and airway inflammation in a murine model of allergic asthma. Thirty-one mice were divided into four groups. Group I (n = 6) served as the control group. Group II (n = 10) mice were sensitized intraperitoneally and challenged intratracheally with cone albumin with no treatment. Group III(n = 6) mice were sensitized, challenged, and treated with Dex for 17 days starting at 24 hours after the first challenge. Group IV (n = 9) mice were sensitized, challenged, and treated with NS fixed oil for 17 days as well. For all groups, the following procedures were carried out: immunohistochemical study of iNOS in lung tissues, detection of PBE percentage, and histopathological examination of lung tissues for inflammatory cells. Lung tissue iNOS expression increased in sensitized, non-treated mice compared with controls, but this increase was not significant. NS fixed oil treatment significantly reduced PBE and lung inflammation but did not significantly reduce lung tissue iNOS expression compared with the control group. These effects were comparable to the effects of Dex. These results suggest that Nigella sativa exhibits immunomodulatory and antiinflammatory effect which may be useful for treatment of allergic asthma.