Estrogenic response of bisphenol A in rainbow trout (Oncorhynchus mykiss)

Bisphenol A (BPA) previously shown to possess xenoestrogenic activities was administered to rainbow trout (Oncorhynchus mykiss) through a continuos flow system. The estrogenic response expressed as the induction of vitellogenin (VTG) synthesis was measured during 12 days of exposure, using a direct sandwich ELISA. Quantification of internal liver and muscle concentrations of non-metabolised BPA was performed by LC-MS at the end of the exposure period. A significant induction of the VTG synthesis was obtained at 500 µg BPA/l exposure, although an increase in the ratio of responding animals was observed already between 40 and 70 µg BPA/l. An increase in VTG levels was observed for the 500 µg BPA/l group over the study period, whereas constant or decreasing levels could be detected in the low exposure groups between days 6 and 12. Average internal liver concentrations of BPA increased from 0.22 to 4.36 µg/g for the 10-500 µg BPA/l groups. However, BPA could not be detected in muscle tissue below an exposure level of 70 µg BPA/l. A dose response relationship was established between the internal liver concentrations of BPA and the corresponding VTG responses, with a P<0.001 and a correlation coefficient of 0.66.