title: Cardiorespiratory toxicity of environmentally relevant zinc oxide nanoparticles in the freshwater fish Catostomus commersonii.
abstract: The inhalation of zinc oxide engineered nanomaterials (ENMs) has been linked to cardiorespiratory dysfunction in mammalian models but the effects of aquatic ENM exposure on fish have not been fully investigated. Nano-zinc oxide (nZnO) is widely used in consumer products such as sunscreens and can make its way into aquatic ecosystems from domestic and commercial wastewater. This study examined the impact of an environmentally relevant nZnO formulation on cardiorespiratory function and energy metabolism in the white sucker (Catostomus commersonii), a freshwater teleost fish. Evidence of oxidative and cellular stress was present in gill tissue, including increases in malondialdehyde levels, heat shock protein (HSP) expression, and caspase 3/7 activity. Gill Na(+)/K(+)-ATPase activity was also higher by approximately three-fold in nZnO-treated fish, likely in response to increased epithelial permeability or structural remodeling. Despite evidence of toxicity in gill, plasma cortisol and lactate levels did not change in animals exposed to 1.0 mg L(-1) nZnO. White suckers also exhibited a 35% decrease in heart rate during nZnO exposure, with no significant changes in resting oxygen consumption or tissue energy stores. Our results suggest that tissue damage or cellular stress resulting from nZnO exposure activates gill neuroepithelial cells, triggering a whole-animal hypoxic response. An increase in parasympathetic nervous signaling will decrease heart rate and may reduce energy demand, even in the face of an environmental toxicant. We have shown that acute exposure to nZnO is toxic to white suckers and that ENMs have the potential to negatively impact cardiorespiratory function in adult fish.
authors.affiliation: a Department of Chemistry and Biochemistry and.
authors.forename: Robin Anne
authors.initials: RA
authors.lastname: Bessemer
authors.affiliation: a Department of Chemistry and Biochemistry and.
authors.forename: Kathryn Marie Alison
authors.initials: KM
authors.lastname: Butler
authors.affiliation: a Department of Chemistry and Biochemistry and.
authors.forename: Louise
authors.initials: L
authors.lastname: Tunnah
authors.affiliation: a Department of Chemistry and Biochemistry and.
authors.forename: Neal Ingraham
authors.initials: NI
authors.lastname: Callaghan
authors.affiliation: a Department of Chemistry and Biochemistry and.
authors.forename: Amanda
authors.initials: A
authors.lastname: Rundle
authors.affiliation: b Department of Biology , Mount Allison University , Sackville , New Brunswick , Canada , and.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Currie
authors.affiliation: c Institute of Biochemistry, Carleton University , Ottawa , Ontario , Canada.
authors.forename: Christopher Anthony
authors.initials: CA
authors.lastname: Dieni
authors.affiliation: a Department of Chemistry and Biochemistry and.
authors.forename: Tyson James
authors.initials: TJ
authors.lastname: MacCormack
mesh_terms: D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D003531:Cypriniformes; D005880:Gills / Q000187:drug effects / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000378:metabolism; D006854:Hydrocortisone / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008315:Malondialdehyde / Q000378:metabolism; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010101:Oxygen Consumption / Q000187:drug effects; D012137:Respiratory System / Q000187:drug effects*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D015034:Zinc Oxide / Q000737:chemistry / Q000633:toxicity*
chemical_list: D006360:Heat-Shock Proteins; D019344:Lactic Acid; D008315:Malondialdehyde; D053148:Caspase 3; D053179:Caspase 7; D000254:Sodium-Potassium-Exchanging ATPase; D015034:Zinc Oxide; D006854:Hydrocortisone
keywords: Biochemistry; environmental toxicology; exposure; mechanistic toxicology; nanotoxicology