PT04 Endocrine-Disrupting Chemicals in Wastewater Treatment Effluents
Exhibit Hall
8:00 AM - Tuesday
(PT062) Inhibition of vitellogenin expression in 17 
-estradiol treated male Japanese medaka by subsequent dihydrotestosterone exposure.
Shi, D1, Xie, L1, Schlenk, D1, 1 University of California, Riverside, CA, USA
ABSTRACT- Although estrogenic activities in wastewater effluent have been extensively studied, little research has been carried out examining androgenic activity in domestic wastewater effluent. In this study, we carried out an in vivo assay using Japanese medaka to assess the endocrine disrupting potential of the androgenic compound dihydrotestosterone (DHT). Following 7 days of exposure to 100 ng/L 17 -estradiol, male medaka were treated with four different concentrations (i.e., 1, 10, 100, 1000 ng/L) of DHT for an additional 7 days and then hepatic vitellogenin was measured by ELISA. Vitellogenin has been extensively applied as a bioindicator of estrogenic activity. The results show that all of the DHT-treated fish had significantly lower vitellogenin concentrations in the liver than both the negative (i.e., 7 days of 17 -estradiol exposure followed by 7 days depuration in clean water) and positive controls (i.e., 7 days of 17 -estradiol exposure only). These results indicate that the enhanced vitellogenin expression resulting from exposure to 17 -estradiol can be downregulated by subsequent DHT treatment. Thus, measuring androgenic activity at various stages of wastewater by this in vivo bioassay can provide evaluation of androgenic activities, which can further our understanding of the fate and occurrence of androgenic agents in reclaimed water and wastewater treatment processes. (Supported by UC-Water Resources Research Institute W-971)
Key words: Dihydrotestosterone, 17 -estradiol , Vitellogenin, Japanese medaka