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An avian bioassay for environmental estrogens: The growth response of zebra finch ( Taeniopygia guttata ) chick oviduct to oral estrogens
Author(s) -
Millam James R.,
CraigVeit Christina B.,
Batchelder Marianne E.,
Viant Mark R.,
Herbeck Tina M.,
Woods Leslie W.
Publication year - 2002
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620211219
Subject(s) - zebra finch , taeniopygia , oviduct , methoxychlor , biology , bioassay , estradiol benzoate , endocrinology , medicine , estrogen , vitellogenin , tributyltin , ovariectomized rat , ecology , pesticide , biochemistry , neuroscience , gene
The rat uterotrophic assay is a recommended tier 1 screening assay for environmental estrogens, but no comparable assay exists for altricial birds. We orally dosed zebra finch chicks daily during their linear growth phase (days 5–11) with estradiol benzoate (EB), genistein, methoxychlor, or octylphenol, all dissolved or suspended in canola oil, or canola oil alone, as a vehicle control. On day 12, oviducts were removed, weighed and examined histologically. All doses of EB (0.1–1,000 nmol/g body wt), genistein at 100 nmol/g, and methoxychlor and octylphenol at 1,000 nmol/g, markedly increased oviduct weight, with the highest dose of EB inducing a 60‐fold increase over controls. Oviducts were differentiated in a dose‐depedent manner to the point of having tubular glands and a pseudostratified, ciliated epithelium at the higher doses of EB. Our earlier results show that EB at 100 and 1,000 nmol/g impairs reproductive performance of zebra finches. Thus, the zebra finch oviduct bioassay measures estrogenicity over a wide dose range and, for EB exposure, can predict impairment in adult reproductive performance. The responsiveness of chick oviducts to estrogen stimulation may serve as a useful marker of estrogen exposure in wild populations of songbirds.