Effects of dietary equol administration on the mammary gland in ovariectomized Sprague-Dawley rats.
OBJECTIVE
To evaluate the effects of dietary equol, a metabolite of soy-derived daidzein or formononetin present in red clover, on the mammary gland of ovariectomized Sprague-Dawley rats.


METHODS
Sixty ovariectomized rats were divided into five groups (n = 12) and fed soy-free chow with the addition of equol (50 mg/kg chow and 400 mg/kg chow) or estradiol-3 benzoate (E2B) (4.3 mg/kg chow and 17.3 mg/kg chow). The control group received soy-free chow only. After 3 months animals were killed, blood was collected, and the mammary glands were removed for histological and immunohistochemical evaluation.


RESULTS
Equol and E2B treatment significantly increased serum equol and 17beta-estradiol concentrations, respectively. Serum prolactin in animals treated with high-dose equol was also significantly higher than in the controls. Animals treated with high-dose equol had a significantly higher number of terminal ducts and type II lobules compared with controls. This was also apparent in animals treated with low- and high-dose E2B, but a higher number of type I lobules also was seen. Compared with controls, animals treated with high-dose equol had a significantly higher percentage of proliferating cell nuclear antigen-positive cells in terminal ducts and type II lobules. The percentage of progesterone receptor-positive cells in animals treated with high-dose equol was significantly higher only in type II lobules. In animals treated with low- and high-dose E2B, the percentage of proliferating cell nuclear antigen- and progesterone receptor-positive cells was significantly higher in all the mammary structures. Low-dose equol did not have any effects on the parameters listed above.


CONCLUSIONS
High-dose dietary equol administration to ovariectomized rats exerts clear mammotropic effects.
Rachoń
Dominik
D
Department of Clinical and Experimental Endocrinology, University of Göttingen, Göttingen, Germany. drachon@amg.gda.pl
Menche
Anne
A
Vortherms
Tina
T
Seidlová-Wuttke
Dana
D
Wuttke
Wolfgang
W
D000818:Animals; D003271:Contraceptive Agents, Female / Q000494:pharmacology; D019587:Dietary Supplements; D004195:Disease Models, Animal; D060754:Equol; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D007529:Isoflavones / Q000494:pharmacology*; D008321:Mammary Glands, Animal / Q000187:drug effects*; D008593:Menopause / Q000187:drug effects*; D010052:Ovariectomy; D048789:Phytoestrogens / Q000494:pharmacology*; D011388:Prolactin / Q000187:drug effects*; D018809:Proliferating Cell Nuclear Antigen / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011980:Receptors, Progesterone / Q000187:drug effects
C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D003271:Contraceptive Agents, Female; D007529:Isoflavones; D048789:Phytoestrogens; D018809:Proliferating Cell Nuclear Antigen; D011980:Receptors, Progesterone; C074283:estradiol 3-benzoate; D004958:Estradiol; D060754:Equol; D011388:Prolactin