title: Retention and maternal transfer of brominated dioxins in zebrafish (Danio rerio) and effects on reproduction, aryl hydrocarbon receptor-regulated genes, and ethoxyresorufin-O-deethylase (EROD) activity.
abstract: Brominated dioxins have recently been detected in Baltic Sea biota. Due to their similarities to the highly toxic chlorinated dioxins, concern has been raised about their potential biological effects. The present study investigated retention and effects of brominated dioxins in adult zebrafish, as well as maternal transfer and effects on offspring. We exposed adult zebrafish for nine weeks via feed to 2,3,7,8-tetrabromodibenzo-p-dioxin (TBDD) or to a mixture of brominated dioxins (Baltic Sea mixture), which was designed to reflect relative concentrations found in Baltic Sea biota. We studied spawning success, gonad morphology, hepatic vitellogenin gene expression, and offspring early life-stage development to investigate effects on zebrafish reproduction. Hepatic ethoxyresorufin-O-deethylase (EROD) activity and hepatic expression of a number of aryl hydrocarbon receptor (AHR)-regulated genes were studied to investigate if the brominated dioxins can activate gene transcription through the AHR pathway in zebrafish. In addition, glutathione reductase activity and expression of genes involved in adaptive responses to intracellular stress were studied to investigate potential stress effects of brominated dioxins. After nine weeks of exposure, all brominated dioxins spiked to the feed were detected in female fish and transferred to eggs. Exposure to the Baltic Sea mixture and TBDD clearly induced AHR-regulated genes and EROD activity. Exposure to TBDD reduced spawning success, altered ovarian morphology and reduced hepatic vitellogenin gene expression, which implies that TBDD has a similar effect pattern as the chlorinated analogue. Overall, our results show that dietary exposure to sublethal concentrations of brominated dioxins may impair reproductive physiology in fish and induce AHR-regulated genes.
authors.affiliation: Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden. anna.norman@bvf.slu.se
authors.forename: A Norman
authors.initials: AN
authors.lastname: Haldén
authors.forename: K
authors.initials: K
authors.lastname: Arnoldsson
authors.forename: P
authors.initials: P
authors.lastname: Haglund
authors.forename: A
authors.initials: A
authors.lastname: Mattsson
authors.forename: E
authors.initials: E
authors.lastname: Ullerås
authors.forename: J
authors.initials: J
authors.lastname: Sturve
authors.forename: L
authors.initials: L
authors.lastname: Norrgren
mesh_terms: D000818:Animals; D002274:Carcinogens, Environmental / Q000633:toxicity*; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics* / Q000378:metabolism; D004147:Dioxins / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006066:Gonads / Q000187:drug effects / Q000473:pathology; D008099:Liver / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics* / Q000378:metabolism; D012098:Reproduction / Q000187:drug effects*; D014819:Vitellogenins / Q000235:genetics / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity; D015027:Zebrafish / Q000378:metabolism / Q000502:physiology*
chemical_list: D002274:Carcinogens, Environmental; D004147:Dioxins; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D014819:Vitellogenins; D014874:Water Pollutants, Chemical; C066841:2,3,7,8-tetrabromodibenzo-4-dioxin; D019363:Cytochrome P-450 CYP1A1