title: Hormone replacement therapy reduces the reactivity of monocytes and platelets in whole blood--a beneficial effect on atherogenesis and thrombus formation?
abstract: OBJECTIVE
  Our purpose was to investigate the effects of hormone replacement therapy on the reactivity of monocytes and platelets in whole blood, measured by tissue factor activity, tumor necrosis factor-alpha, and thromboxane B2.
  
  
  METHODS
  Thirty-two women were randomized into either transdermal or oral combined hormone replacement therapy and underwent blood sampling before and after 3 and 12 months of treatment. The tissue factor activity in monocytes was measured both in unstimulated whole blood and after a weak lipopolysaccharide stimulation. Tumor necrosis factor-alpha and thromboxane B2 formation in plasma were measured after a weak lipopolysaccharide stimulation of whole blood.
  
  
  RESULTS
  After 12 months of hormone replacement therapy there were significant reductions of tissue factor activity in both unstimulated and lipopolysaccharide-stimulated monocytes (p < 0.001) and significant reductions in the formation of tumor necrosis factor-alpha (p < 0.03) and thromboxane B2 (p < 0.02). There were no differences in these parameters between the transdermal and the oral groups. No changes were observed after 3 months of therapy.
  
  
  CONCLUSIONS
  Twelve months of hormone replacement therapy reduces cellular activation of blood monocytes and platelets; these changes may account for some of the beneficial effects in reducing the risk of cardiovascular disease.
authors.affiliation: Department of Obstetrics and Gynecology, University of Tromsø, Norway.
authors.forename: B
authors.initials: B
authors.lastname: Aune
authors.forename: P
authors.initials: P
authors.lastname: Oian
authors.forename: I
authors.initials: I
authors.lastname: Omsjø
authors.forename: B
authors.initials: B
authors.lastname: Osterud
mesh_terms: D000279:Administration, Cutaneous; D000284:Administration, Oral; D000328:Adult; D001161:Arteriosclerosis / Q000517:prevention & control; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D008525:Medroxyprogesterone / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D009640:Norethindrone / Q000008:administration & dosage / Q000494:pharmacology*; D013925:Thromboplastin / Q000187:drug effects / Q000378:metabolism*; D013927:Thrombosis / Q000517:prevention & control; D013929:Thromboxane B2 / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000187:drug effects / Q000378:metabolism
chemical_list: D014409:Tumor Necrosis Factor-alpha; D004958:Estradiol; D013929:Thromboxane B2; D013925:Thromboplastin; D008525:Medroxyprogesterone; D009640:Norethindrone