Involvement of peroxynitrite in LPS-induced apoptosis of trophoblasts

Objective: To examine whether or not peroxynitrite was involved in trophoblastic apoptosis induced by a bacterial endotoxin, lipopolysaccharide (LPS). Methods: Levels of nitrite/nitrate, stable metabolites of nitric oxide (NO), in culture medium of trophoblasts, were determined using Griess reagents. Trophoblastic apoptosis was identified morphologically and confirmed using in situ nick end labeling technique. The amount of nitrotyrosine, a footprint of peroxynitrite, was quantified by dot blotting. Statistical significance was determined by ANOVA. Results: Treatment of trophoblasts with LPS leads to apoptosis accompanied by formation of NO and nitrotyrosine. Aminoguanidine, an inhibitor of NO synthase (NOS), reduced peroxynitrite formation and prevented apoptosis. Scavengers of peroxynitrite also prevented apoptosis in this culture model. Conclusion: Peroxynitrite was involved in trophoblastic apoptosis induced by LPS. Peroxynitrite scavengers or inhibitors of NOS may thus be candidate therapeutic agents for infectious diseases, which is associated with overproduction of NO and peroxynitrite.