title: Blood flow variations in internal carotid and middle cerebral arteries induced by postmenopausal hormone replacement therapy.
abstract: OBJECTIVE
  Our purpose was to clarify the mechanisms by which postmenopausal estrogen replacement therapy exerts its protective effect on cardiovascular risk.
  
  
  METHODS
  By means of a bidirectional Doppler ultrasonographic system we measured pulsatility index variations the internal carotid artery and middle cerebral artery in 25 early postmenopausal women during a 6-month period of hormone replacement therapy. Transdermal estradiol (50 micrograms/day) was continuously administered. A 12-day course of medroxyprogesterone acetate (10 mg/day) was added every second month.
  
  
  RESULTS
  The pulsatility index showed a significant (p = 0.0001) reduction in both arteries after 6 weeks. At 22 weeks a 25% reduction was measured. No variation of the estrogen-induced pulsatility index reduction was observed at the end of every cyclic progestogen supplementation.
  
  
  CONCLUSIONS
  In early postmenopausal women hormone replacement therapy causes a rapid reduction of pulsatility index in brain arteries. Cyclical progestational supplementation does not modify this positive effect on reactivity of the blood vessels.
authors.affiliation: Second Obstetrical and Gynecological Department, University of Milan, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Penotti
authors.forename: T
authors.initials: T
authors.lastname: Nencioni
authors.forename: L
authors.initials: L
authors.lastname: Gabrielli
authors.forename: M
authors.initials: M
authors.lastname: Farina
authors.forename: E
authors.initials: E
authors.lastname: Castiglioni
authors.forename: F
authors.initials: F
authors.lastname: Polvani
mesh_terms: D000279:Administration, Cutaneous; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000187:drug effects*; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000187:drug effects*; D004958:Estradiol / Q000627:therapeutic use; D015914:Estrogen Replacement Therapy; D004970:Estrone / Q000031:analogs & derivatives / Q000652:urine; D005260:Female; D006801:Humans; D017258:Medroxyprogesterone Acetate / Q000627:therapeutic use; D008875:Middle Aged; D011673:Pulsatile Flow / Q000187:drug effects; D012039:Regional Blood Flow / Q000187:drug effects; D014463:Ultrasonography
chemical_list: C015856:estrone-3-glucuronide; D004970:Estrone; D004958:Estradiol; D017258:Medroxyprogesterone Acetate