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COMPARISON OF THE ESTROGENIC POTENCIES OF ESTRADIOL, ETHYNYLESTRADIOL, DIETHYLSTILBESTROL, NONYLPHENOL AND METHOXYCHLOR IN VIVO AND IN VITRO
Citation:
Folmar, L C., M J. Hemmer, N D. Denslow, K. Kroll, J. Chen, A. Cheek, H. Richman, H. Meredith, AND G. Grau. COMPARISON OF THE ESTROGENIC POTENCIES OF ESTRADIOL, ETHYNYLESTRADIOL, DIETHYLSTILBESTROL, NONYLPHENOL AND METHOXYCHLOR IN VIVO AND IN VITRO. AQUATIC TOXICOLOGY 60(1-1):101-110, (2002).
Description:
Five natural, pharmaceutical, or xenobiotic chemicals (17b-estradiol, ethynylestradiol, diethystilbestrol, nonylphenol, methoxychlor) were tested in two in vitro (MCF-7 breast tumor cell proliferation [E-screen], yeast estrogen system [YES]), and one in vivo (male sheepshead minnow vitellogenin production) assays. EC50 values for all five chemicals were approximately one order of magnitude less sensitive in the YES assay than in the MCF-7 assay. DES was 1.6 (YES) to 2.9 (MCF-7) times more active in these receptor binding assays than was E2. The relative estrogenic potency (%) of the xenobiotic chemicals compared to 17b-estradiol were approximately equal in the two in vitro assays. Estradiol, EE2 and DES (at 200 ng/L) were of equal potency in the 13-day sheepshead minnow vitellogenin (VTG) production bioassay. In the in vitroassays, both methoxychlor and nonylphenol were 106 to 107 times less estrogenic than the native ligand 17b-estradiol, while in the live animal bioassay methoxychlor was (0.2 - 2.8%) and nonylphenol was (0.6 - 1.2%) as efficient at inducing vitellogenin (VTG) synthesis in male fish as was E2. The in vitro tests were substantially less sensitive than the sheepshead minnow VTG assay for estimating estrogenic potency of the two xenobiotic chemicals, which suggests that an in vitro-based large-scale screening program could potentially result in many false negative evaluations.