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 LPS-treated 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 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.