title: A comparison of oral micronized estradiol with soy phytoestrogen effects on tail skin temperatures of ovariectomized rats.
abstract: OBJECTIVE
  Whether phytoestrogen-containing soy supplements have beneficial effects on hot flashes of postmenopausal women and how those effects, if any, compare to estrogen replacement therapy has been uncertain. It is possible that the uncertainty is due to the low doses of soy isoflavones (30-60 mg per day) used in the studies. We used ovariectomized retired breeder rats and a higher dose of soy phytoestrogens to approach these uncertainties experimentally.
  
  
  METHODS
  The treatment groups were as follows: (1) Control group fed a casein/lactalbumin-based diet; (2) Soy(-) group fed alcohol-washed soy protein isolate with the phytoestrogens extracted; (3) Soy(+) group fed phytoestrogen-containing soy protein (equivalent to a woman's dose of 144 mg isoflavones per day)--a dose two to three times higher than that in most studies with women; and (4) E2 group fed oral micronized estradiol (E2) at a dose equivalent to a woman's dose of 1 mg per day. A temperature-transponder was taped to the surface of the tail to measure temperature. Tail skin temperature was significantly increased within a week after ovariectomy. The animals were pair-fed during the last 21 days of treatment for daily temperature measurement.
  
  
  RESULTS
  Soy(-) had no effect on skin temperature. E2 had a large effect on skin temperature (about 1.4 degrees C reduction from Control). Soy(+) was intermediate between the E2 treatment and no treatment (about 0.8 degrees C reduction from Control).
  
  
  CONCLUSIONS
  Soy phytoestrogens have a modest effect on average skin temperatures, being about half that of E2, even at high doses in the rat model.
authors.affiliation: Comparative Medicine Clinical Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Pan
authors.forename: M S
authors.initials: MS
authors.lastname: Anthony
authors.forename: M
authors.initials: M
authors.lastname: Binns
authors.forename: T B
authors.initials: TB
authors.lastname: Clarkson
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D004195:Disease Models, Animal; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D004968:Estrogens, Non-Steroidal / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D019584:Hot Flashes / Q000517:prevention & control*; D007529:Isoflavones; D010052:Ovariectomy; D048789:Phytoestrogens; D028321:Plant Preparations; D051381:Rats; D017207:Rats, Sprague-Dawley; D030262:Soybean Proteins / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D013623:Tail
chemical_list: D004968:Estrogens, Non-Steroidal; D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations; D030262:Soybean Proteins; D004958:Estradiol