Vitellogenin as a biomarker for estrogenic effects in brown trout, **Salmo trutta** : laboratory and field investigations
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences. Pharmacy
New York, N.Y.
Environmental toxicology and chemistry. - New York, N.Y.
, p. 2387-2396
The sensitivity of juvenile brown trout towards estrogenic chemicals (17β-estradiol [E2], estrone [E1], 17α-ethinyles-tradiol [EE2], 4-tert-octylphenol [OP], and n-butylparaben [BP]) was tested in laboratory experiments with plasma and liver vitellogenin concentrations as endpoints. Vitellogenin concentrations were also assessed in juvenile brown trout collected in streams affected by agricultural runoff and discharges from scattered houses in the open land. In the laboratory, juvenile brown trout were exposed to the chemicals in flow-through tanks for 7 to 12 d and concentrationresponse relationships for the induction of vitellogenin synthesis were obtained. The actual exposure concentrations were determined by liquid chromatographymass spectrometry. The median plasma vitellogenin concentration in first year control brown trout reared in recirculated groundwater was 165 ng/ml with 783 ng/ml as the highest value. The median effective concentration (EC50) values for vitellogenin induction (based on plasma concentrations) were 3.7 ng EE2/L, 15 ng E2/L, 88 ng E1/L, 68 μg BP/L, and 7 μg OP/L. Median effective concentrations derived from liver vitellogenin concentrations were similar. The 166 brown trout caught in the field were mainly first and second year fish and a few third year fish. Plasma vitellogenin concentrations were below 1,000 ng/L in 146 of the fish, between 1,000 ng/L and 4,234 ng/L in 19 fish and 5.3 × 106 ng/L in one male fish. Vitellogenin concentrations did not differ between first and second year fish, but were elevated in third year fish. The data may indicate that juvenile (<2 years) trout with plasma vitellogenin concentrations above 1,000 ng/ml have had their vitellogenin synthesis induced by exposure to estrogens in the environment. Plasma and liver vitellogenin concentrations were closely correlated in brown trout with elevated vitellogenin concentrations. It is noteworthy, however, that exposure to synthetic estrogens (EE2, BP, and OP) resulted in higher liver concentrations (for the same plasma concentration) than exposure to the natural estrogens E1 and E2.