Redox evaluation in sepsis model mice by the in vivo ESR technique using acyl-protected hydroxylamine

• Published in: Free radical biology & medicine 2014-03, Vol.68, p.72-79
• Main Authors: Okazaki, Shoko, Tachibana, Yoko, Koga-Ogawa, Yukari, Takeshita, Keizo
• Format: Article
• Language: English
• Subjects: Acyl-protected hydroxylamine; Animals; Disease Models, Animal; Electron Spin Resonance Spectroscopy; Free radicals; Hydroxylamine - administration & dosage; In vivo ESR; Lipopolysaccharides - toxicity; Male; Mice; Nitroxyl radical; Oxidation-Reduction; Oxidative stress; Oxidative Stress - drug effects; Pyrrolidines - administration & dosage; Reactive oxygen species; Reactive Oxygen Species - metabolism; Redox; Sepsis; Sepsis - chemically induced; Sepsis - metabolism; Sepsis - pathology
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2013.11.011

In vivo electron spin resonance (ESR) spectroscopy is a noninvasive technique that measures the oxidative stress in living experimental animals. The rate of decay of the ESR signal right after an injection of nitroxyl radical has been measured to evaluate the oxidative stress in animals, although the probe’s disposition could also affect this rate. Because the amount of probes forming the redox pair of hydroxyl amine and its corresponding nitroxyl radical was shown to be nearly constant in most organs or tissues 10min after the injection of 1-acetoxy-3-carbamoyl-2,2,5,5-tetramethylpyrrolidine (ACP) in mice, we evaluated the oxidative stress in sepsis model mice induced by lipopolysaccharide (LPS) by intravenously injecting ACP as a precursor of redox probes. The in vivo ESR signal increased up to 7–8min after the ACP injection and then decreased. Decay of the in vivo signal in LPS-treated mice was significantly slower than that in healthy mice, whereas no significant difference was observed in the rate of change in the total amount of redox probes in the blood and liver between these groups. ESR imaging showed that the in vivo signals observed at the chest and upper abdomen decayed slowly in LPS-treated mice. Suppression of the decay in LPS-treated mice was canceled by the administration of a combination of pegylated superoxide dismutase and catalase, or an inhibitor of nitric oxide synthase, or gadolinium chloride. These results indicate that the LPS-treated mouse is under oxidative stress and that reactive oxygen species, such as superoxide and peroxynitrite, related to macrophages are mainly involved in the oxidative stress. [Display omitted] •In vivo ESR signal of nitroxyl radical was durable in LPS-treated mice.•The signal duration was inhibited by either SOD + catalase or L-NAME.•The signal duration was also inhibited by GdCl3, an inactivator for macrophages.•Macrophage-related O2− and ONOO− should be involved in LPS-induced oxidative stress.