title: Estrogen, inflammation, and platelet phenotype.
abstract: BACKGROUND
  Although exogenous estrogenic therapies increase the risk of thrombosis, the effects of estrogen on formed elements of blood are uncertain.
  
  
  OBJECTIVE
  This article examines the genomic and nongenomic actions of estrogen on platelet phenotype that may contribute to increased thrombotic risk.
  
  
  METHODS
  To determine aggregation, secretion, protein expression, and thrombin generation, platelets were collected from experimental animals of varying hormonal status and from women enrolled in the Kronos Early Estrogen Prevention Study.
  
  
  RESULTS
  Estrogen receptor beta predominates in circulating platelets. Estrogenic treatment in ovariectomized animals decreased platelet aggregation and adenosine triphosphate (ATP) secretion. However, acute exposure to 17beta-estradiol did not reverse decreases in platelet ATP secretion invoked by lipopolysaccharide. Thrombin generation was positively correlated to the number of circulating microvesicles expressing phosphatidylserine.
  
  
  CONCLUSIONS
  Assessing the effect of estrogen treatments on blood platelets may lead to new ways of identifying women at risk for adverse thrombotic events with such therapies.
authors.affiliation: Department of Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota, USA. miller.virginia@mayo.edu
authors.forename: Virginia M
authors.initials: VM
authors.lastname: Miller
authors.forename: Muthuvel
authors.initials: M
authors.lastname: Jayachandran
authors.forename: Kazumori
authors.initials: K
authors.lastname: Hashimoto
authors.forename: John A
authors.initials: JA
authors.lastname: Heit
authors.forename: Whyte G
authors.initials: WG
authors.lastname: Owen
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D047629:Estrogen Receptor beta / Q000378:metabolism; D004967:Estrogens / Q000494:pharmacology; D020022:Genetic Predisposition to Disease; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008593:Menopause / Q000502:physiology; D010974:Platelet Aggregation / Q000502:physiology; D011960:Receptors, Estrogen / Q000378:metabolism*; D013927:Thrombosis / Q000235:genetics / Q000503:physiopathology*; D051197:Toll-Like Receptor 4 / Q000008:administration & dosage
chemical_list: D047629:Estrogen Receptor beta; D004967:Estrogens; D008070:Lipopolysaccharides; D011960:Receptors, Estrogen; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D004958:Estradiol