Simultaneous comparison of L-NAME and melatonin effects on RAW 264.7 cell line's iNOS production and activity.

Background: NO (nitric oxide) inhibition could be used for evaluating the drug's efficacy for NO-mediated inflammatory disorders. The aim of this study was to investigate the influence of L-NAME and melatonin on different NO production levels in RAW 264.7 cell line as an in vitro model for inflammatory diseases. Materials and methods: RAW 264.7 macrophage cell line was used to compare the effects of L-NAME and melatonin on basal and Lipopolysaccharide (LPS)-induced iNOS levels. The cells were treated using L-NAME and melatonin for 1 h, afterward incubated with/without LPS for 8 and 24 h. Finally, iNOS mRNA, protein, activity, and nitrite concentrations were evaluated. Results: Inhibition rate of nitrite by 1 mM L-NAME compared with LPS control were 78% and 80% during 8 and 24 h, respectively. Real-time PCR showed that in the LPStreated group, 1 mM L-NAME could result in 14% increase of iNOS-mRNA compared with the control group during 8 h. Dose-dependent activity of iNOS in LPS-induced cells from non-treated to 4 mM L-NAME showed 79% reduction while at the same concentrations of melatonin this decrease was 32% (p-value <0.05). Conclusion: L-NAME showed lower iNOS expression modulating efficacy than melatonin. The result concluded lower potential of the NOS synthetic inhibitors rather than melatonin in the treatment of NO-related disorders. [ABSTRACT FROM AUTHOR]