Physiological and transcriptional effects of mixtures of environmental estrogens, androgens, progestins and glucocorticoids in zebrafish.

Fish are exposed to mixtures of different class steroids but ecotoxicological implications are not sufficiently known. Here we systematically analyze effects of different combinations of steroid mixtures in zebrafish embryos to assess their joint activities on physiology and transcriptional alterations of steroid-specific target genes at 96 and 120 hours post fertilization. In binary mixtures of clobetasol propionate (CLO) with estradiol (E2) or androstenedione (A4) each steroid exhibited its expression profile. This was also the case in mixtures of five, eight and 13 different class steroids in exposure concentrations of 10-10000 ng/L. Transcriptional expression of most genes in different mixtures was steroid-specific with the exception of genes encoding aromatase (cyp19b), sulfatase (sult2st3) and cyp2k22 that were induced by androgens, progestins and glucocorticoids. Marked alterations occurred for sult2st3 in binary mixtures of CLO+E2 and CLO+A4. Glucocorticoids increased heart rate and muscle contrac...