Korean J Otolaryngol-Head Neck Surg.  2000 Feb;43(2):136-142.

Effect of Antioxidants and Dexamethasone on inducible Nitric Oxide Synthase Expression and Nitric Oxide Production in Murine Macrophage Cells

• Kang JM
• Yeo SW
• Lee HY
• Chang KH
• Suh BD

Abstract

BACKGROUND AND OBJECTIVES
Nitric oxide(NO) plays a role in a number of physiologic functions and may be cytotoxic in high concentrations. Some kinds of cells including macrophage are known to produce large quantities of NO in response to inflammatory stimuli such as cytokines and lipopolysaccharide(LPS). Reactive oxygen species are also known to be important in the pathogenesis of cell and tissue injury such as otitis media with effusions. Using the macrophage RAW 264.7 cell, we have examined the ability of oxidant hydrogen peroxide (H2O2) to stimulate NO production and inducible nitric oxide synthase(iNOS) mRNA expression. Also, we have examined the effects of Dexamethasone(DEX) and antioxi- dants on H2O2 induced NO production. MATERIALS AND METHOD: Macrop- hages were cultured with LPS and H2O2 in the presence or absence of DEX or antioxidants for 24 hr. The effect of DEX and antioxidants on NO production and iNOS mRNA expression was examined by assaying the culture supernatant for oxidation product nitrite(NO-2) and nitrate (NO-3) content and Northern blot analysis. The effect of DEX on NO production when added at different stages of activation was determined.
RESULTS
DEX significantly inhibited the formation of NO2- and NO3- and iNOS mRNA expression in cells stimulated with LPS and H2O2. Antioxid- ants significantly inhibited the H2O2-induced augmentation of LPS induced NO2- and NO3- formation and iNOS mRNA expression.
CONCLUSION
H2O2 contributes to inflammatory process by augmenting the iNOS mRNA expression and NO synthesis induced by LPS, and DEX and anti- oxidants inhibits NO synthesis by inhibition of iNOS mRNA expression.

Keyword

iNOS; Nitric oxide; Dexamethasone; antioxidants

MeSH Terms

Antioxidants*
Ants
Blotting, Northern
Cytokines
Dexamethasone*
Hydrogen Peroxide
Macrophages*
Nitric Oxide Synthase Type II*
Nitric Oxide*
Otitis Media
Oxidants
Reactive Oxygen Species
RNA, Messenger
Antioxidants
Cytokines
Dexamethasone
Hydrogen Peroxide
Nitric Oxide
Nitric Oxide Synthase Type II
Oxidants
RNA, Messenger
Reactive Oxygen Species