| Sexual Behavior in Japanese Quail as a Test End Point for Endocrine Disruption: Effects of in Ovo Exposure to Ethinylestradiol and Diethylstilbestrol Krister Halldin, Cecilia Berg, Ingvar Brandt, and Björn Brunström Department of Environmental Toxicology, Uppsala University, Uppsala, Sweden Abstract
Chemicals having a capacity to disturb the endocrine system have attracted considerable interest during recent years. There is a shortage of well-characterized in vivo tests with which to study such disturbances in different classes of vertebrates. In the present study, test end points related to reproduction in the Japanese quail were used to examine the estrogenic activity of chemicals. The synthetic estrogens ethinylestradiol (EE2) and diethylstilbestrol (DES) , used as model compounds, were injected into the yolk of embryonated eggs. After the birds had been raised to sexual maturity, we examined sexual behavior, plasma testosterone concentrations, and testis morphology in adult males. The lowest doses resulting in a significantly depressed male sexual behavior were 6 ng/g egg for EE2 and 19 ng/g egg for DES. Testis weight asymmetry was increased at 6 ng EE2/g egg, but DES had no effect at any treatment level. The area of the androgen-dependent cloacal gland was significantly reduced at 57 ng DES/g egg. No effects on plasma testosterone concentration or body weight following exposure to EE2 or DES were observed at any dose level. Depressed male sexual behavior was the most sensitive of the end points studied, and we suggest that this ecologically relevant end point be included in avian in vivo testing for neuroendocrine disruptors. Key words: diethylstilbestrol, endocrine disruption, environmental estrogens, ethinylestradiol, Japanese quail, sexual behavior, testis, testosterone, test system. Environ Health Perspect 107:861-866 (1999) . [Online 1 October 1999] http://ehpnet1.niehs.nih.gov/docs/1999/107p861-866halldin/ abstract.html Address correspondence to K. Halldin, Department of Environmental Toxicology, Uppsala University, Norbyvägen 18C, 75236 Uppsala, Sweden. Telephone: 46 18 4712601. Fax: 46 18 518843. E-mail: Krister.Halldin@etox.uu.se We thank L. Plöen at the Swedish University of Agricultural Sciences for assisting in the evaluation of testis morphology. Financial support was provided by the Foundation for Strategic Environmental Research (MISTRA) , the Swedish Council for Forestry and Agricultural Research (SJFR) , and by the Swedish Environmental Protection Agency. Received 22 March 1999 ; accepted 17 June 1999.
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