Feminization and altered gonadal gene expression profile by ethynylestradiol exposure to pejerrey, Odontesthes bonariensis, a South American teleost fish

PEREZ, M.R.; FERNANDINO, J.I.; CARRIQUIRIBORDE, P; SOMOZA, G.M.

ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY

SETAC PRESS

Año: 2012 vol. 31 p. 941 - 946

0730-7268

In pejerrey, the ovarian differentiation has been associated with gonadal aromatase expression and it is also known that exposure of pejerrey larvae to estradiol (E2) produces all female populations. During the last years the presence of ethynylestradiol (EE2), an E2 analogue, has been reported in water reservoirs of different parts of the world. Here, the effects of EE2 were assessed on sex ratios and gene expression levels of gonadal aromatase (cyp19a1a), 11β-hydroxysteroid deshydrogenase 2 (11βhsd2), estrogens (erα, erβ1) and androgens receptors (arα, arβ). Pejerrey larvae were fed with commercial food containing EE2 (0.1 µg/g and 1 µg/g), and E2 (50 µg/g) as a positive control for 6 weeks after hatching. The gonadal histological analysis showed that 42-46% of the fish had clearly differentiated ovaries both, in the EE2 and E2 treated groups, compared to 27 % in the control group. Moreover, in EE2 (1 µg/g) and E2 treated groups, no fish presented signs of testicular development compared to controls. In addition, the expression of cyp19a1a and 11βhsd2 were respectively significantly up- and down-regulated by EE2 and E2. Our results suggested that the feminization process driven by EE2 depends on the positive balance of cyp19a1a in relation to 11βhsd2. These genes can then be used as early indicators of exposure to xenoestrogens in this species.