Differential activation pattern of redox-sensitive transcription factors and stress-inducible dilator systems heme oxygenase-1 and inducible nitric oxide synthase in hemorrhagic and endotoxic shock

• Published in: Critical care medicine Vol. 29; no. 10; p. 1962
• Main Authors: Rensing, H, Jaeschke, H, Bauer, I, Pätau, C, Datene, V, Pannen, B H, Bauer, M
• Format: Journal Article
• Language: English
• Published: United States 01.10.2001
• Subjects: Animals; Blotting, Northern; Blotting, Western; Disease Models, Animal; Gene Expression Regulation; Heme Oxygenase (Decyclizing) - genetics; Heme Oxygenase (Decyclizing) - metabolism; Male; Nitric Oxide Synthase - genetics; Nitric Oxide Synthase - metabolism; Probability; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species - metabolism; Reference Values; RNA - analysis; Sensitivity and Specificity; Shock, Hemorrhagic - blood; Shock, Hemorrhagic - metabolism; Shock, Septic - blood; Shock, Septic - metabolism
• ISSN: 0090-3493
• DOI: 10.1097/00003246-200110000-00019

To investigate the role of redox-sensitive transcription factors nuclear factor kappa-B (NF-kappaB) or activator protein-1 (AP-1) for hepatic gene expression of heme oxygenase (HO)-1 and inducible nitric oxide synthase (iNOS) in models of hemorrhagic or endotoxic shock. Prospective controlled laboratory study. Animal research laboratory at a university hospital. Male Sprague-Dawley rats (250-350 g). After anesthesia, animals were assigned to hemorrhagic shock (mean arterial pressure 35-40 mm Hg for 60 mins), sham operation, or endotoxemia (1 mg/kg intraperitoneally). To assess the role of reactive oxygen species for activation of NF-kappaB or AP-1, animals were treated with the antioxidant trolox (6 mg/kg body weight). In additional experiments, animals were pretreated with dexamethasone (10 mg/kg body weight), an inhibitor of the transactivating function of DNA-bound AP-1 or with actinomycin-D (2 mg/kg body weight), an inhibitor of DNA-directed RNA synthesis. Activation of NF-kappaB or AP-1 was assessed by electrophoretic mobility shift assay. HO-1 and iNOS gene expression were assessed by Northern and Western blot. Hemorrhage and resuscitation induced hepatic HO-1 transcripts 12-fold. Induction was abolished by actinomycin-D and was attenuated by dexamethasone and the antioxidant trolox. Activation of AP-1 was observed after hemorrhagic but not after endotoxic shock. AP-1 activation was inhibitable by trolox and correlated with accumulation of HO-1 transcripts. In contrast, a weak activation of NF-kappaB was observed after hemorrhage that was not affected by trolox. A profound activation of NF-kappaB after endotoxic shock correlated with induction of iNOS but failed to induce HO-1 transcripts. These data suggest that AP-1 but not NF-kappaB activation is dependent on reactive oxygen intermediates in vivo and contributes to HO-1 gene expression. Thus, AP-1-dependent HO-1 induction under oxidative stress conditions may subserve a similar function as a stress-inducible vasodilator system as does NF-kappaB-dependent iNOS expression in liver inflammation.