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(18-63) Effects of the estrogen 17- van den Brandhof, E.J.1, Vos, J.H.*,1, Druke, J.M.1, Beekhof, P.K.1, Berrag, S.1, van der Ven, L.T.M.1, Wester, P.W.1, 1 P.O. Box 1, Bilthoven, The Netherlands ABSTRACT- van den Brandhof E.J., J.H. Vos, J.M. Druke, P.K. Beekhof, S. Berrag, L.T.M. van der Ven, P.W. Wester, National Institute of Public Health and the Environment, Bilthoven, The Netherlands. To determine the toxicological impact of endocrine disrupting chemicals, we have developed a partial life cycle test (PLC test) with zebrafish as test organism. With this test the effects of a 3-weeks exposure to estrogenic chemicals on the reproduction of adult zebrafish and on the development of their offspring until 6 weeks of age (after sexual differentiation) were measured. Studied endpoints were: weight, length, egg production, fertilization rate, hatching ratio, vitellogenin (VTG) levels in blood plasma, VTG immunohistochemistry and histological determinants (e.g. liver, gonads, circulation, thyroid, sexual differentiation). The zebrafish PLC test is being validated with a set of complementing hormone-active reference compounds, including estrogen, anti-estrogen, androgen, anti-androgen and anti-thyroid agents. The poster presents preliminary results of the zebrafish PLC test with the estrogen 17-B-Estradiol (E2) and the anti-thyroid 6-n-Propyl-2-Thiouracil (PTU). It appeared that the higher the PTU concentration, the more broods and eggs were spawned. There was a significant positive correlation in total number of produced eggs per female after 3 weeks PTU exposure, while in the E2 exposure no correlation was obtained. In the case of E2 spawning appears not to be a sensitive parameter. Sex differentiation of 6 weeks old juveniles was not influenced in the PTU exposure, while a statistical significant (P=0.001, single factor ANOVA) decrease in percentage of male juveniles was found with increasing E2 dose, with a concomitant increase in the percentage of females (not significant). Life history variables will be further used to estimate endocrine effects at population level. Key words: Endocrine disruptors, Fish, Reproduction, Bioassay |
-Estradiol and the anti-thyroid Propylthiouracil in a Partial Life Cycle test with Zebrafish.