We have reported: 1) A standard method for conducting the mouse bioassay for the detection of estrogenic activity in rodent diets; 2) that rodent diets significantly differ in estrogenic activity; 3) that some rodent diets contain high concentrations of daidzein and genistein equivalent to 4.3 ppb of DES activity and that these phytoestrogens may alter the results of comparative estrogenic and carcinogenicity studies; 4) that metabolizable energy in rodent diets can significantly influence the uterine:body weight ratios of immature CD-1 mice used in uterotrophic assays; 5) that natural ingredient diets can be formulated to contain less than detectable levels of the phytoestrogens daidzein and genistein by omitting the soybean and alfalfa meals; and 6) the dietary phytoestrogens daidzein and genistein significantly increase vaginal openings in CD-1 mice. Our recommendations have greatly influenced the type of diets used at the national and international level in the conduct of comparative estrogenic and carcinogenicity studies.
| Thigpen, Julius E; Setchell, Kenneth D R; Padilla-Banks, Elizabeth et al. (2007) Variations in phytoestrogen content between different mill dates of the same diet produces significant differences in the time of vaginal opening in CD-1 mice and F344 rats but not in CD Sprague-Dawley rats. Environ Health Perspect 115:1717-26 |
| Thigpen, Julius E; Haseman, Joseph K; Saunders, Hannah et al. (2002) Dietary factors affecting uterine weights of immature CD-1 mice used in uterotrophic bioassays. Cancer Detect Prev 26:381-93 |
