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PT07 Chemical and Biological Analysis of Endocrine Disrupting Compounds
(PT128) Rapid detection of (anti)ecdysteroid and (anti)juvenoid activities of chemicals.
Wang, H, Mu, X, LeBlanc, G A1, 1 NC State University, Raleigh, NC
ABSTRACT- The Endocrine Disruptors Screening and Testing Committee (EDSTAC) recommended to EPA that methods be explored to screen chemicals for endocrine toxicity to invertebrates. Among the arthropod invertebrates ecdysteroid and juvenoid hormones regulate many of the same processes that are under the control of estrogens, androgens, and thyroid hormone in vertebrates. The purpose of the present research was to develop a screening assay that would detect (anti)ecdysteroid and (anti)juvenoid activities of chemicals. Daphnid (Daphnia magna) embryo development was selected as the screening endpoint as we have shown that normal embryo development requires the involvement of ecdysteroids and sex of the embryo is determined by juvenoids. Gravid female daphnids were individually exposed to various chemical individually or in combination both in the absence and presence of the male-sex determining hormone methyl farnesoate. Offspring were assessed for developmental abnormalities and sex. Chemicals with know anti-ecdysteroid activity (i.e., fenarimol, piperonyl butoxide) were detected by the production of offspring that were not fully developed. Chemicals with known juvenoid activity (i.e. fenoxycarb, pyriproxyfen) were accurately detected by the production of male offspring. In addition, interactions were observed among chemicals. For example, bisphenol A alone exhibited no hormonal activity but in the presence of a juvenoid, it enhanced the potency of the juvenoid and elicited antiecdysteroid activity. Results demonstrate that chemicals can be screened for ecdysteroid/juvenoid-related activities. This screen would provide mechanistic support for performing Phase II testing for endocrine toxicity with invertebrate species.
Key words: juvenoid, ecdysteroid, endocrine, screening
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