Copper levels and changes in pH induce oxidative stress in the tissue of curimbata (Prochilodus lineatus)

• Published in: Aquatic toxicology 2015-10, Vol.167, p.220-227
• Main Authors: Carvalho, Cleoni dos Santos, Bernusso, Vanessa Aline, Fernandes, Marisa Narciso
• Format: Article
• Language: English
• Subjects: Animals; Copper - toxicity; Enzymatic antioxidants; Fish; Fishes - physiology; Gills - drug effects; Hydrogen-Ion Concentration; Liver - drug effects; Liver - enzymology; Metal; Metallothionein; Metallothionein - metabolism; Oxidative Stress - drug effects; Oxidoreductases - metabolism; Prochilodus lineatus; Water Pollutants, Chemical - toxicity
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2015.08.003

•Water pH affects antioxidant enzyme activities.•The effect of Cu on oxidative stress responses is determined by water pH.•Copper toxicity is higher in water at pH 8.0.•Gills, liver, and muscles exhibit different sensitivity to water pH and copper levels.•Interactions between pH and Cu affect the activity of all antioxidant enzymes. We analyzed the effect of exposure to 25% 96h-LC50 of copper at low (24.5μgL−1 Cu, pH 4.5), neutral (7.25μgL−1 Cu, pH 7.0) and high pH (4.0μgL−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.