title: In vitro exposure of Nile tilapia (Oreochromis niloticus) testis to estrogenic endocrine disrupting chemicals: mRNA expression of genes encoding steroidogenic enzymes.
abstract: Many environmental pollutants can exert adverse effects on exposed organisms, including fish, leading to disruption of the endocrine system. Enzymes involved in the sex steroid biosynthesis are potential targets for the toxic action of pollutants. In this context, we investigated the hypothesis that selected estrogenic chemicals-the pharmaceutical estrogen ethinylestradiol (EE2), the phytoestrogen genistein (GEN), and the industrial compound bisphenol A (BPA)-may cause endocrine disruption by directly disturbing steps of fish steroidogenic pathways. We studied the mRNA expression of eight selected genes encoding steroidogenic enzymes (11β-HSD2, 20β-HSD, 3β-HSD1, 17β-HSD1, 17β-HSD8, 17β-HSD12, CYP19a, CYP19b) by quantitative real-time PCR. Testis slices from adult specimens of the model fish Nile tilapia were exposed in vitro for 3 and 8 h either to individual or to mixture solutions of EE2 (100 ng/L), GEN (200 ng/L), and BPA (10 µg/L); all at the peak concentrations observed in the Douro River estuary (Portugal). Our data revealed that only the mixture of the tested chemicals directly induced the expression of 11β-HSD2, 17β-HSD1, and 17β-HSD12, after 8 h, whereas no effect was seen for chemicals tested individually. The gene expression pattern agrees with the concept of dose addition for environmental mixtures, and for the first time an interference of estrogenic EDCs is reported for 17β-HSD1 and 17β-HSD12.
authors: Interdisciplinary Centre for Marine and Environmental Research (CIIMAR), CIMAR Associate Laboratory, University of Porto (UPorto), Portugal.
authors: Cláudia
authors: C
authors: Ribeiro
authors: Ralph
authors: R
authors: Urbatzka
authors: L Filipe C
authors: LF
authors: Castro
authors: João
authors: J
authors: Carrola
authors: António
authors: A
authors: Fontainhas-Fernandes
authors: Rogério A F
authors: RA
authors: Monteiro
authors: Eduardo
authors: E
authors: Rocha
authors: Maria J
authors: MJ
authors: Rocha
mesh_terms: D015067:17-Hydroxysteroid Dehydrogenases / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001141:Aromatase / Q000235:genetics / Q000378:metabolism; D023681:Cichlids / Q000235:genetics / Q000378:metabolism*; D052244:Endocrine Disruptors / Q000633:toxicity*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D012739:Gonadal Steroid Hormones / Q000096:biosynthesis; D066298:In Vitro Techniques; D008297:Male; D012333:RNA, Messenger / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D013737:Testis / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism
chemical_list: D052244:Endocrine Disruptors; D012739:Gonadal Steroid Hormones; D012333:RNA, Messenger; D015067:17-Hydroxysteroid Dehydrogenases; D001141:Aromatase