title: Antioxidant responses of Laeonereis acuta (Polychaeta) after exposure to hydrogen peroxide.
abstract: The effects of H2O2 were evaluated in the estuarine worm Laeonereis acuta (Polychaeta, Nereididae) collected at the Patos Lagoon estuary (Southern Brazil) and maintained in the laboratory under controlled salinity (10 psu diluted seawater) and temperature (20 degrees C). The worms were exposed to H2O2 (10 and 50 microM) for 4, 7, and 10 days and the following variables were determined: oxygen consumption, catalase (CAT) and glutathione peroxidase activity in both the supernatant and pellet fractions of whole body homogenates. The concentrations of non-protein sulfhydryl and lipid peroxides (LPO) were also measured. The oxygen consumption response was biphasic, decreasing after 4 days and increasing after 7 and 10 days of exposure to 50 microM H2O2 (P < 0.05). At the same H2O2 concentration, CAT activity was lower (P < 0.05) in the pellet fraction of worms exposed for 10 days compared to control. Non-protein sulfhydryl concentration and glutathione peroxidase activity were not affected by H2O2 exposure. After 10 days, LPO levels were higher (P < 0.05) in worms exposed to 50 microM H2O2 compared to control. The reduction in the antioxidant defense was paralleled by oxidative stress as indicated by higher LPO values (441% compared to control). The reduction of CAT activity in the pellet fraction may be related to protein oxidation. These results, taken together with previous findings, suggest that the worms were not able to cope with this H2O2 concentration.
authors.affiliation: Programa de Pós-Graduação em Ciências Fisiológicas - Fisiologia Animal Comparada, Departamento de Ciências Fisiológicas, Fundação Universidade Federal do Rio Grande, Rio Grande, RS, Brasil.
authors.forename: C E da
authors.initials: CE
authors.lastname: Rosa
authors.forename: A
authors.initials: A
authors.lastname: Bianchini
authors.forename: J M
authors.initials: JM
authors.lastname: Monserrat
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000187:drug effects / Q000378:metabolism*; D004785:Environmental Pollutants / Q000633:toxicity; D005979:Glutathione Peroxidase / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000633:toxicity*; D008054:Lipid Peroxides / Q000032:analysis; D018384:Oxidative Stress / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects*; D011077:Polychaeta / Q000187:drug effects* / Q000201:enzymology; D013438:Sulfhydryl Compounds / Q000032:analysis; D013997:Time Factors
chemical_list: D000975:Antioxidants; D004785:Environmental Pollutants; D008054:Lipid Peroxides; D013438:Sulfhydryl Compounds; D006861:Hydrogen Peroxide; D002374:Catalase; D005979:Glutathione Peroxidase