Original paper :AATEX 8(1):23-30
We evaluated the utility of whole embryo culture for the screening technique of the potency of endocrine active chemicals in rat embryos. Rat embryos on embryonic day 11 (ED11) were exposed to two estrogenic chemicals, estradiol benzoate (EB) and diethylstilbestrol (DES), for 42 hr in culture. The treated embryos showed some morphological defects in the cardiovascular system, such as edema around umbilical vessels (EB- and DES-treated groups), enlargement of the heart (EB) and hemorrhage of the head (DES) at high doses. To determine the mediation of estrogen receptors to these morphological defects, we also studied the expression of estrogen receptor a (ER-a) in embryos both by immunohistochemistry and by Western blotting. Immunohistochemistry revealed positive grains stained with anti-ER- a antibody in both the cytoplasm and nucleus of heart and yolk sac in EDs 12 and 13 rat embryos. The staining pattern of anti-ER-a antibody in embryos was different from the positive control, the uterus of adult rats. In addition, the expression of ER-a protein in these embryos was not detected by Western blotting. These results suggest that the embryotoxicity in this study is not mediated by ER-a. Further modifications of whole embryo culture as a screening technique are needed to detect the embryotoxicity of endocrine active compounds.
Keywords: estrogenic compounds, estrogen receptor-a, immunohistochemistry, Western blotting, whole rat-embryo culture