Evaluation of estrogenic activity in diets for experimental animals using in vitro assay.
We used a modified yeast-based human estrogen receptor alpha (ER alpha) bioassay to determine the estrogenic activity in 22 kinds of diets for experimental animals. The estrogenic activity of each diet was reevaluated by comparison with a calibration curve of 17 beta-estradiol. Almost all of the diets had estrogenic activity. The diets for rabbits and guinea pigs had the highest estrogenic activity compared to any other diets, including those for rats and mice. Estrogenic activity was found in dried skim milk, fishmeal, soybean meal, and alfalfa meal. In the NIH-07 diet opened for the ingredients, estrogenic activity was nearly all derived from the alfalfa meal. Multiple assays were performed to evaluate potential seasonal variations in the estrogenic potency in the raw materials of the rat and mouse diets. We found that the estrogenic activity in these raw materials changed throughout the year.
Kato
Hideo
H
Nihon Bioresearch Inc., 6-104 Majima, Fukuju-cho, Hashima 501-6251, Japan.
Iwata
Toshio
T
Katsu
Yoshinao
Y
Watanabe
Hajime
H
Ohta
Yasuhiko
Y
Iguchi
Taisen
T
D000821:Animal Feed / Q000032:analysis; D000818:Animals; D000830:Animals, Laboratory; D001681:Biological Assay; D004032:Diet; D004958:Estradiol / Q000032:analysis / Q000378:metabolism; D047628:Estrogen Receptor alpha; D004967:Estrogens / Q000008:administration & dosage* / Q000032:analysis; D006168:Guinea Pigs; D006801:Humans; D007529:Isoflavones / Q000032:analysis; D051379:Mice; D048789:Phytoestrogens; D028321:Plant Preparations / Q000032:analysis; D011817:Rabbits; D051381:Rats; D011960:Receptors, Estrogen
D047628:Estrogen Receptor alpha; D004967:Estrogens; D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations; D011960:Receptors, Estrogen; D004958:Estradiol