Mechanism of estrogen-mediated attenuation of hepatic injury following trauma-hemorrhage: Akt-dependent HO-1 up-regulation.
Protein kinase B (Akt) is known to be involved in proinflammatory and chemotactic events in response to injury. Akt activation also leads to the induction of heme oxygenase (HO)-1. Up-regulation of HO-1 mediates potent, anti-inflammatory effects and attenuates organ injury. Although studies have shown that 17beta-estradiol (E2) prevents organ damage following trauma-hemorrhage, it remains unknown whether Akt/HO-1 plays any role in E2-mediated attenuation of hepatic injury following trauma-hemorrhage. To study this, male rats underwent trauma-hemorrhage (mean blood pressure, approximately 40 mmHg for 90 min), followed by fluid resuscitation. At the onset of resuscitation, rats were treated with vehicle, E2 (1 mg/kg body weight), E2 plus the PI-3K inhibitor (Wortmannin), or the estrogen receptor (ER) antagonist (ICI 182,780). At 2 h after sham operation or trauma-hemorrhage, plasma alpha-GST and hepatic tissue myeloperoxidase (MPO) activity, IL-6, TNF-alpha, ICAM-1, cytokine-induced neutrophil chemoattractant-1, and MIP-2 levels were measured. Hepatic Akt and HO-1 protein levels were also determined. Trauma-hemorrhage increased hepatic injury markers (alpha-GST and MPO activity), cytokines, ICAM-1, and chemokine levels. These parameters were markedly improved in the E2-treated rats following trauma-hemorrhage. E2 treatment also increased hepatic Akt activation and HO-1 expression compared with vehicle-treated, trauma-hemorrhage rats, which were abolished by coadministration of Wortmannin or ICI 182,780. These results suggest that the salutary effects of E2 on hepatic injury following trauma-hemorrhage are in part mediated via an ER-related, Akt-dependent up-regulation of HO-1.
Hsu
Jun-Te
JT
Center for Surgical Research and Department of Surgery, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Kan
Wen-Hong
WH
Hsieh
Chi-Hsun
CH
Choudhry
Mashkoor A
MA
Schwacha
Martin G
MG
Bland
Kirby I
KI
Chaudry
Irshad H
IH
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D054360:Chemokine CXCL1 / Q000096:biosynthesis; D054426:Chemokine CXCL2 / Q000096:biosynthesis; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology; D000077267:Fulvestrant; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005982:Glutathione Transferase / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000096:biosynthesis*; D006470:Hemorrhage / Q000201:enzymology* / Q000473:pathology; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis; D008099:Liver / Q000201:enzymology* / Q000293:injuries* / Q000473:pathology; D008297:Male; D009195:Peroxidase / Q000096:biosynthesis; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000378:metabolism; D012151:Resuscitation; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D015854:Up-Regulation / Q000187:drug effects; D000077191:Wortmannin; D014947:Wounds and Injuries / Q000201:enzymology* / Q000473:pathology
D000730:Androstadienes; D054360:Chemokine CXCL1; D054426:Chemokine CXCL2; D004958:Estradiol; D004965:Estrogen Antagonists; D004967:Estrogens; D000077267:Fulvestrant; D005982:Glutathione Transferase; D051547:Heme Oxygenase-1; D018799:Intercellular Adhesion Molecule-1; D015850:Interleukin-6; D009195:Peroxidase; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D011960:Receptors, Estrogen; D014409:Tumor Necrosis Factor-alpha; D000077191:Wortmannin; C513297:Cxcl1 protein, rat; C513296:Cxcl2 protein, rat