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.
OBJECTIVE
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.


METHODS
Prospective controlled laboratory study.


METHODS
Animal research laboratory at a university hospital.


METHODS
Male Sprague-Dawley rats (250-350 g).


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Rensing
H
H
Department of Anesthesiology and Critical Care Medicine, University of the Saarland, Homburg, Germany.
Jaeschke
H
H
Bauer
I
I
Pätau
C
C
Datene
V
V
Pannen
B H
BH
Bauer
M
M
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism*; D008297:Male; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D011336:Probability; D012313:RNA / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012016:Reference Values; D012680:Sensitivity and Specificity; D012771:Shock, Hemorrhagic / Q000097:blood / Q000378:metabolism*; D012772:Shock, Septic / Q000097:blood / Q000378:metabolism*
D017382:Reactive Oxygen Species; D012313:RNA; D019001:Nitric Oxide Synthase; D006419:Heme Oxygenase (Decyclizing)