title: Tissue distribution of zinc and subtle oxidative stress effects after dietary administration of ZnO nanoparticles to rainbow trout.
abstract: The increasing use of ZnO nanoparticles (ZnO NPs) in different fields has raised concerns about the possible environmental risks associated with these NPs entering aquatic systems. In this study, using a dietary exposure route, we have analysed the tissue distribution and depuration pattern of Zn as well as any associated redox balance disturbances in rainbow trout (Oncorhynchus mykiss) following exposure to ZnO NPs (20-30nm). Fish were fed a diet spiked with ZnO NPs prepared from a dispersion in sunflower oil at doses of 300 or 1000mg ZnO NPs/kg feed for 10days. This uptake phase was followed by a 28days depuration phase in which fish from all groups received untreated feed. While no overt signs of toxicity were observed and no important effects in fish growth (weight and length) or in the hepatosomatic index among groups were recorded, we observed high levels of Zn bioaccumulation in the gills and intestine of exposed fish following exposure to both dose levels. Zn levels were not eliminated during the depuration phase and we have evidenced oxidative stress responses in gills associated with such long term ZnO NPs bioaccumulation and lack of elimination. Furthermore, exposures to higher doses of ZnO NPs (1000mg/kg feed) resulted in Zn distribution to the liver of fish following 10days of exposure. Fish from this exposure group experienced biochemical disturbances associated with oxidative stress in the liver and ethoxy-resorufin-O-deethylase (EROD) activity which may point to the ability of ZnO NPs or its ions to interfere with cytochrome P450 metabolic processes.
authors.affiliation: Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Crta. de la Coruña, km. 7,5, 28040 Madrid, Spain.
authors.forename: Mona
authors.initials: M
authors.lastname: Connolly
authors.affiliation: Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Av. Complutense, 40, 28040 Madrid, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Fernández
authors.affiliation: Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Av. Complutense, 40, 28040 Madrid, Spain.
authors.forename: Estefanía
authors.initials: E
authors.lastname: Conde
authors.affiliation: E.T.S. Ingenieros de Montes, Universidad Politécnica de Madrid, Campus Montegancedo, Calle ciruelos, s/n, 28660 Boadilla del Monte, Madrid, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Torrent
authors.affiliation: Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Crta. de la Coruña, km. 7,5, 28040 Madrid, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Navas
authors.affiliation: Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Crta. de la Coruña, km. 7,5, 28040 Madrid, Spain. Electronic address: fcruz@inia.es.
authors.forename: María L
authors.initials: ML
authors.lastname: Fernández-Cruz
mesh_terms: D000818:Animals; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D053758:Nanoparticles / Q000378:metabolism / Q000633:toxicity*; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D018384:Oxidative Stress; D014018:Tissue Distribution; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*; D015032:Zinc / Q000378:metabolism*; D015034:Zinc Oxide / Q000378:metabolism / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D019363:Cytochrome P-450 CYP1A1; D005978:Glutathione; D015032:Zinc; D015034:Zinc Oxide
keywords: Bioaccumulation; Dietary exposure; Oxidative stress; Rainbow trout (Oncorhynchus mykiss); Tissue distribution; Zinc oxide nanoparticles (ZnO NPs)