We have previously described the necessary parameters for conducting the mouse bioassay for detecting estrogenic activity in animal diets, including a standardized method for removing, trimming, and weighing the uterus, age and strain of test pups, and methods of statistical evaluation. Statistical evaluation (t-test) of bioassay data has shown that uterine weight alone, without calculated uterine: body weight ratio, is adequte to determine a statistically significant (P.05) difference between control diets containing 0, 4, or 6 ppb DES. We have also employed the mouse bioassay using the CD-1 mouse to compare the estrogenic activity of semipurified, certified, standard and open formula rodent diets. Mice fed semipurified diet (AIN-76), modified semipurified diet containing 4% corn oil, or a natural ingredient breeder diet (Purina #5015), demonstrated significant (P less than .05) increases in uterine weight at 5, 7, and 9 days post weaning, when compared to other natural ingredient diets. This level of estrogenic activity was equal to or greater than the activity observed in a natural ingredient maintenance diet (Purina #5002), containing 4 or 6 ppb of DES. These results suggest: 1) significant differences exist in the level of estrogenic activity in some commercially available diets; 2) the importance of the diet when performing or comparing fertility, reproduction, organogenesis, toxicological or estrogenic studies; 3) a standardized diet with minimal estrogenic activity may be desirable for some studies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Intramural Research (Z01)
Project #
1Z01ES022104-02
Application #
4693198
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
2
Fiscal Year
1985
Total Cost
Indirect Cost
Name
U.S. National Inst of Environ Hlth Scis
Department
Type
DUNS #
City
State
Country
United States
Zip Code