Estrogen ameliorates trauma-hemorrhage-induced lung injury via endothelial nitric oxide synthase-dependent activation of protein kinase G.
OBJECTIVE
In this study, we tested the hypothesis that 17beta-estradiol (E2) administration after trauma-hemorrhage reduces lung injury through a mechanism involving estrogen receptor (ER)-dependent activation of the endothelial nitric oxide (NO) synthase (eNOS)/protein kinase G (PKG)/vasodilator-stimulated phosphoprotein (VASP) pathway.


BACKGROUND
Estrogen provides protection after injury via activation of multiple signaling cascades, including the cyclic GMP-dependent PKG pathway. Phosphorylation of VASP at Ser239 (p-VASP) can be used to assess PKG signaling activity.


METHODS
Male Sprague-Dawley rats (275-325 g) underwent soft tissue trauma (midline laparotomy) and hemorrhagic shock (mean blood pressure 35-40 mm Hg for 90 minutes) followed by fluid resuscitation. Animals were pretreated with a nonselective NOS inhibitor (N(omega)-nitro-L-arginine methyl ester; 30 mg/kg), a soluble guanylyl cyclase (sGC) inhibitor [1H-(1, 2, 4) oxadiazolo (3, 4-alpha) quinoxalin-1-one; 10 mg/kg] or an ER antagonist (ICI 182,780; 3 mg/kg) 30 minutes before E2 (100 microg/kg) or vehicle administration. Animals were killed at 2 hours after resuscitation.


RESULTS
Lung injury induced by trauma-hemorrhage is evidenced by edema (wet/dry ratio), neutrophil infiltration (myeloperoxidase activity), and with an increased expression of cytokines, chemokines, and adhesion molecules. E2 treatment after trauma-hemorrhage resulted in an increase in eNOS expression/phosphorylation, PKG-I activation, and VASP/p-VASP expression, which paralleled a decrease in lung injury. Inhibition of NOS and sGC abolished the E2-induced increase in PKG-I activity, VASP/p-VASP expression. Blockade of eNOS, PKG-I, and ER exacerbated lung inflammation and injury.


CONCLUSIONS
These results collectively suggest that activation of the eNOS-PKG/VASP pathway by E2 protects against trauma-hemorrhage-induced lung injury.
Kan
Wen-Hong
WH
Department of Surgery, Center for Surgical Research, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019, USA.
Hsu
Jun-Te
JT
Schwacha
Martin G
MG
Choudhry
Mashkoor A
MA
Bland
Kirby I
KI
Chaudry
Irshad H
IH
D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000187:drug effects / Q000378:metabolism; D018925:Chemokines / Q000032:analysis / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D016207:Cytokines / Q000032:analysis / Q000378:metabolism*; D004195:Disease Models, Animal; D004965:Estrogen Antagonists / Q000494:pharmacology*; D018836:Inflammation Mediators / Q000378:metabolism; D008171:Lung Diseases / Q000517:prevention & control*; D055370:Lung Injury; D008297:Male; D008840:Microfilament Proteins / Q000187:drug effects / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000187:drug effects / Q000378:metabolism; D010750:Phosphoproteins / Q000187:drug effects / Q000378:metabolism; D011336:Probability; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012680:Sensitivity and Specificity; D012771:Shock, Hemorrhagic / Q000150:complications; D015398:Signal Transduction; D014947:Wounds and Injuries / Q000150:complications; D000098662:Vasodilator-Stimulated Phosphoprotein
D015815:Cell Adhesion Molecules; D018925:Chemokines; D016207:Cytokines; D004965:Estrogen Antagonists; D018836:Inflammation Mediators; D008840:Microfilament Proteins; D010750:Phosphoproteins; D000098662:Vasodilator-Stimulated Phosphoprotein; D052250:Nitric Oxide Synthase Type III; D017869:Cyclic GMP-Dependent Protein Kinases