Objective: 

Nitric oxide and superoxide radicals react each other to form peroxynitrite (ONOO-) that is far more toxic and reactive than its precursors, and is a relatively long-lived oxidant. ONOO- is a potent oxidant and nitrating agent which causes modifications, and reacts with numerous biomolecules including proteins, lipids, thiols, sulfhydryl groups and DNA bases. A well known reaction of ONOO- is forming 3-Nitrotyrosine (3-NT) by nitrating free or protein-bound tyrosine residues from ortho position. 3-NT, a stable and specific end product of ONOO-, is a biomarker that is used commonly for determining ONOO--mediated tissue damage in human disease and animal models. On the other hand, taurine is a free sulfur-containing beta-amino acid which has antioxidant, antiinflammatory and detoxificant properties. In this study, the role of endotoxemia on ONOO- formation via 3-NT detection, and the antioxidant effect of taurine in lipopolysaccharide (LPS)-treated guinea pigs were investigated.

Methods: 

Forty adult male guinea pigs were injected LPS (4 mg/kg), taurine (300 mg/kg) or taurine plus LPS intraperitoneally, and levels of 3-NT and taurine were measured by HPLC in spleen tissues. The One Way ANOVA test was used to analyze the significance of the differences between control and experimental groups.

Results: 

LPS administration significantly decreased the concentration of taurine whilst increased levels of 3-NT. It was determined that taurine decreased the levels of 3-NT in taurine plus LPS-treated group. The group in which taurine was administered alone, contradictory to its well-known antioxidant effect, taurine caused elevated concentration of 3-NT.

Conclusions: 

Taurine may act as an antioxidant during endotoxemia, while it may also act as a prooxidant in healthy conditions.