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ENDOCRINE DISRUPTION IN AN AVIAN MODEL: THE EFFECT OF METHOXYCHLOR ON STEROID HORMONES.
Wu, Julie1, Ottinger, Mary Ann1, 1
ABSTRACT- Methoxychlor (MXC) is a widely used pesticide with known estrogenic effects. We investigated the cross-generational effects of dietary pesticide exposure, at levels below federal concentration limits, on serum steroid levels in Japanese quail (Coturnix japonica). Reproductively mature Japanese quail were paired (P1) and fed MXC-treated feed: control (0 ppm), low (0.5 ppm) and high (5.0 ppm) for 8 weeks (Wildlife International Inc., Easton, MD) and then sampled. Two hatches (F1 generation) were raised on the same treatment as their parents and then sacrificed at early pubertal (F1-EP) and adult stages (F1-AD) to study maturational effects. A subset of F1 birds were paired within treatments and an F2 generation was raised on untreated feed and sampled at onset of puberty to study effects of maternal deposition. Serum estradiol and androgens were measured by single antibody RIA (Endocrine Sciences). Feed intake, body weight, egg production and fertility did not differ between treatments. Among P1 birds, estradiol levels did not differ between treatments, but male androgen levels were reduced (p≤0.05) in low and high MXC-treated birds; females showed no differences. F1-EP treated males, but not females, had slightly lower (p=0.06) androgen levels; estradiol levels, however, were not different. Among F1-AD birds, high treatment male estradiol levels were lower (p≤0.05) than control or low birds. Female low birds had higher (p≤0.05) androgen levels than control or high animals. Androgen and estradiol levels in treated F2 females decreased (p≤0.05), however, males showed no differences. In conclusion, these results indicate that serum steroid levels may be more sensitive than gross reproductive indices (e.g. productivity, fertility), in evaluating endocrine disruption. Furthermore, the observed hormone patterns suggest a delayed onset of puberty in treated birds. Supported by EPA R826134010
KEY WORDS: methoxychlor, endocrine disrupting chemical, steroid hormone, bird