title: In vitro effects of tibolone and its metabolites on human vascular coronary cells.
abstract: OBJECTIVE
  Tibolone is a tissue selective compound with estrogenic, androgenic and progestogenic properties in classical bioassays. It is used for alleviation of menopausal symptoms and for osteoporosis prophylaxis in postmenopausal women. Only few data are available regarding the effects of tibolone on the cardiovascular system. We investigated therefore the in vitro effects of tibolone and its metabolites on the vasculature under special controlled conditions, using human female coronary endothelial and smooth muscle cells.
  
  
  METHODS
  The effect on the production of the following markers in endothelial cells from human female coronary arteries was evaluated: nitric oxide synthase, prostacyclin, endothelin, plasminogen-activator-inhibitor-1 (PAI-1), E-Selectin, Intercellular adhesion molecule (ICAM-1), monocyte attracting protein-1 (MCP-1) and the precursor of matrix metalloproteinase-1 (pro-MMP-1). Tibolone, its metabolites, estradiol (E2), E2/norethisterone (NET) and E2/medroxyprogesterone acetate (MPA) were tested at 0.1 microM and 1 microM. The markers were determined by enzyme immunoassays in the cell supernatant. Cell proliferation of smooth muscle cells from female coronary artery was measured by an adenosine triphosphate-assay.
  
  
  RESULTS
  Tibolone, its 3-hydroxy metabolites, E2/NET, E2/MPA and estradiol alone had significant effects on the synthesis of all markers tested. The magnitude of the tibolone effects, however, was mostly smaller than that of E2/NET and E2/MPA. Concerning smooth muscle cells tibolone and its 3-hydroxy metabolites also elicited an inhibition of the proliferation compared to control values. The strongest effect here was found for E2/NET and E2 alone, whereas E2/MPA had no effect.
  
  
  CONCLUSIONS
  The results of this in vitro study conducted with cells of the most important vascular bed with respect to the problem of cardiovascular risk suggest that tibolone can positively influence the vasculature. However, these tibolone effects may depend on intact vascular cells and may vary due to the different atherosclerotic stages of the vessels. Thus, experimental studies are useful to explore mechanisms, but clearly cannot replace clinical studies.
authors.affiliation: Department of Endocrinology and Menopause, University's Women Hospital, Calwerstrasse 7, 72 076 Tuebingen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Seeger
authors.forename: H J
authors.initials: HJ
authors.lastname: Kloosterboer
authors.forename: M
authors.initials: M
authors.lastname: Studen
authors.forename: D
authors.initials: D
authors.lastname: Wallwiener
authors.forename: A O
authors.initials: AO
authors.lastname: Mueck
mesh_terms: D015415:Biomarkers / Q000097:blood*; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology* / Q000187:drug effects; D019040:E-Selectin / Q000097:blood; D016232:Endothelins / Q000097:blood; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D011464:Epoprostenol / Q000097:blood; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000097:blood; D020781:Matrix Metalloproteinase 1 / Q000097:blood; D017258:Medroxyprogesterone Acetate / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000097:blood; D009640:Norethindrone / Q000494:pharmacology; D009652:Norpregnenes / Q000494:pharmacology*; D017395:Plasminogen Activator Inhibitor 1 / Q000097:blood; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D015415:Biomarkers; D019040:E-Selectin; D016232:Endothelins; D009652:Norpregnenes; D017395:Plasminogen Activator Inhibitor 1; D018799:Intercellular Adhesion Molecule-1; D004958:Estradiol; D017258:Medroxyprogesterone Acetate; D011464:Epoprostenol; D019001:Nitric Oxide Synthase; D020781:Matrix Metalloproteinase 1; C027385:tibolone; D009640:Norethindrone