title: Estrogen-induced vasoprotection is estrogen receptor dependent: evidence from the balloon-injured rat carotid artery model.
abstract: BACKGROUND
  Previous studies have shown that estrogen (E2) is vasoprotective in multiple animal models of vascular injury, including mice with homologous disruptions of either the alpha or beta isoforms of the estrogen receptor (ER) gene, calling into question the ER dependency of the vasoprotective effect. This study used ICI 182,780, a nonselective ER antagonist, to test the hypothesis that the vasoprotective effect of E2 in the rat carotid injury model is ER mediated.
  
  
  RESULTS
  Intact female Sprague-Dawley rats were divided into 4 groups and treated with the nonselective ER antagonist ICI 182,780 (ICI; 0.5, 1.5, or 5 mg. kg(-1). d(-1), subcutaneously [S.C.]) or vehicle, beginning before balloon injury of the right common carotid artery and continuing for 14 days afterward. Four groups of ovariectomized rats (OVX) were treated with 17beta estradiol (E2) (20 microgram. kg(-1). d(-1), S.C.) alone or combined with ICI 5 mg. kg(-1). d(-1), S.C.; with ICI 5 mg. kg(-1). d(-1) alone; or with vehicle according to a similar protocol. Two weeks after injury, rats were killed, and the carotid arteries were evaluated for neointima formation using morphometric analysis. ICI 182,780 blunted the E2-related protective effect and increased neointima formation in injured carotid arteries of intact female rats in a dose-dependent fashion. ICI had no effect on neointima formation in OVX, but addition of ICI to E2 in OVX blocked the inhibitory effect of exogenous E2 on neointima formation.
  
  
  CONCLUSIONS
  These results indicate that the vasoprotective effect of E2 in the balloon-injured rat carotid artery model is mediated by ER.
authors.affiliation: The Vascular Biology and Hypertension Program, Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, USA. sbakir@uab.edu
authors.forename: S
authors.initials: S
authors.lastname: Bakir
authors.forename: T
authors.initials: T
authors.lastname: Mori
authors.forename: J
authors.initials: J
authors.lastname: Durand
authors.forename: Y F
authors.initials: YF
authors.lastname: Chen
authors.forename: J A
authors.initials: JA
authors.lastname: Thompson
authors.forename: S
authors.initials: S
authors.lastname: Oparil
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000502:physiology*; D020212:Carotid Artery Injuries / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D002404:Catheterization / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D004967:Estrogens / Q000502:physiology*; D005260:Female; D000077267:Fulvestrant; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000502:physiology*; D017539:Tunica Intima / Q000473:pathology
chemical_list: D004338:Drug Combinations; D004965:Estrogen Antagonists; D004967:Estrogens; D011960:Receptors, Estrogen; D000077267:Fulvestrant; D004958:Estradiol