Estrogen induced changes in Akt-dependent activation of endothelial nitric oxide synthase and vasodilation.
OBJECTIVE
Acute administration of estrogen results in vasodilation and increased nitric oxide (NO) production. We examined the hypothesis that this is due to activation of Akt/PKB which subsequently increases eNOS activity.


RESULTS
Treatment of bovine microvascular and human umbilical endothelial cells (HUVEC) with 17-beta-estradiol (E2) (10(-9) to 10(-5)M) increased phosphorylation of Akt within 1 min and this was followed by phosphorylation of eNOS. These effects were blocked by wortmannin, a PI(3)K inhibitor and the upstream activator of Akt. The estrogen receptor antagonist, ICI 182,780, inhibited eNOS phosphorylation. E2 increased calcium dependent NOS activity and nitrite production and this was inhibited by wortmannin and ICI 182,780. E2 increased the vasodilatory response of aortic rings to acetylcholine and wortmannin blocked the effect. E2 (10(-9)M) dilated cerebral microvascular vessels under conditions of no flow, constant flow and increasing flow and this was blocked by wortmannin. Tamoxifen, a partial estrogen receptor antagonist, also dilated the microvessels.


CONCLUSIONS
: E2 increases NO production through an Akt/PKB dependent pathway. This is associated with increased sensitivity to endothelial dependent dilation. In cerebral microvessels, E2 and tamoxifen produce significant dilation at low concentrations with and without acetylcholine induced stimulation of endothelial vasodilation.
Critical Care Division, Department of Neuroanaesthesia, McGill University Health Center, Montreal, Que., Canada.
Maria
M
Florian
Yan
Y
Lu
Mark
M
Angle
Sheldon
S
Magder
D000109:Acetylcholine / Q000494:pharmacology; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D015153:Blotting, Western; D002417:Cattle; D002460:Cell Line; D002550:Cerebral Veins / Q000187:drug effects / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D005260:Female; D000077267:Fulvestrant; D006801:Humans; D066298:In Vitro Techniques; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D009573:Nitrites / Q000378:metabolism; D010052:Ovariectomy; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017207:Rats, Sprague-Dawley; D013629:Tamoxifen / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*; D000077191:Wortmannin
D000730:Androstadienes; D004965:Estrogen Antagonists; D009573:Nitrites; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D013629:Tamoxifen; D000077267:Fulvestrant; D004958:Estradiol; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; C494918:AKT1 protein, human; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D000109:Acetylcholine; D000077191:Wortmannin