title: Copper levels and changes in pH induce oxidative stress in the tissue of curimbata (Prochilodus lineatus).
abstract: We analyzed the effect of exposure to 25% 96 h-LC50 of copper at low (24.5 μg L(-1) Cu, pH 4.5), neutral (7.25 μg L(-1) Cu, pH 7.0) and high pH (4.0 μg L(-1) Cu, pH 8.0) at 20 °C on antioxidant defenses and oxidative stress in the liver, gills and white muscle of the fish Prochilodus lineatus. Water at pH 4.5 and 8.0 affected the enzymatic and non-enzymatic antioxidant systems of the liver and gills, but not of the white muscles of P. lineatus, when compared to water at pH 7.0. After Cu exposure, SOD (superoxide dismutase), GPx (glutathione peroxidase), GR (glutathione reductase) and GST (glutathione S-transferase) activities increased and CAT (catalase) activity decreased in the liver at water at pH 4.5 and 8.0. Meanwhile, the activities of SOD, CAT, GPx, GR and GST increased in the gills at these pHs. SOD and CAT activities increased in the white muscle after Cu exposure at pH 8.0 and GPx, GR and GST activities decreased after Cu exposure at pH 4.5 and 8.0. LPO levels decreased in the liver and gills of fish that were exposed to water at pH 4.5 and 8.0 and, after Cu exposure, the LPO level increased in the liver, gills and white muscle of fish that were exposed to water at pH 4.5 and 8.0, when compared to the control group at pH 7.0. The metallothionein (MT) concentration increased in the liver of fish in water at pH 4.5 and 8.0 and the gill of fish in water at pH 8.0. After Cu exposure, MT in the liver and gills was significantly elevated in fish exposed to water at pH 4.5 and 8.0, but remained at levels similar to the control group in the white muscle. These results indicate a differing sensitivity of fish organs and tissues to essential metals, such as copper, and that toxicity may be relevant at environmental concentrations. These results indicate that the effect of Cu on the response of antioxidant defense systems is determined by water pH.
authors.affiliation: Department of Biology, Universidade Federal de São Carlos, Sorocaba Campus, Rodovia João Leme dos Santos, km 110 SP-264, CEP 18052-780 Sorocaba, São Paulo, Brazil. Electronic address: san-cleo@ufscar.br.
authors.forename: Cleoni dos Santos
authors.initials: Cdos S
authors.lastname: Carvalho
authors.affiliation: Department of Physiological Sciences, Universidade Federal de São Carlos, Caixa Postal 676, Rodovia Washington Luis km 235, CEP 13565-905 São Carlos, SP, Brazil.
authors.forename: Vanessa Aline
authors.initials: VA
authors.lastname: Bernusso
authors.affiliation: Department of Physiological Sciences, Universidade Federal de São Carlos, Caixa Postal 676, Rodovia Washington Luis km 235, CEP 13565-905 São Carlos, SP, Brazil.
authors.forename: Marisa Narciso
authors.initials: MN
authors.lastname: Fernandes
mesh_terms: D000818:Animals; D003300:Copper / Q000633:toxicity*; D005399:Fishes / Q000502:physiology*; D005880:Gills / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008668:Metallothionein / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D010088:Oxidoreductases / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D003300:Copper; D008668:Metallothionein; D010088:Oxidoreductases
keywords: Enzymatic antioxidants; Fish; Metal; Metallothionein