title: Behaviour of the oxidant scavenger metallothionein in hypoxia-induced neotropical fish.
abstract: The pacu (Piaractus mesopotamicus) is a hypoxia-tolerant neotropical fish species. There is little or no information in this species regarding biochemical adaptations to waters with different oxygen concentrations, such as the production of reactive oxygen species and antioxidant scavengers, which might be of interest in the study of antioxidant defense mechanisms. Metallothioneins (MT) have been widely applied as biomarkers for metal exposure in fish liver, and, recently, in bile. These metalloproteins, however, have also been reported as free radical scavengers, although studies in this regard are scarce in fish. In this context, normoxic and hypoxic controlled experiments were conducted with pacu specimens and MT levels were quantified in both liver and bile. Reduced glutathione (GSH) indicative of oxidative stress, and thiobarbituric acid reactive substances (TBARS), indicative of lipid peroxidation, were also determined in liver. The results demonstrate that hypoxic fish present significantly lower metallothionein levels in liver and bile and lower reduced glutathione levels in liver, whereas lipid peroxidation was not significantly different between hypoxic and normoxic fish. The results of the present study seem to suggest that metallothioneins may actively participate in redox regulation in hypoxic fish in both bile and liver. MT levels in these organs may be temporarily suppressed, supporting the notion that down-regulation of oxidant scavengers during the oxidative burst is important in defense signaling in these adapted organisms.
authors.affiliation: Instituto de Química/UNICAMP, Grupo de Espectrometria, Preparo de amostras e Mecanização-GEPAM, C. Postal 6154, 13084-971 Campinas, SP, Brazil; National Institute of Science and Technology for Bioanalitics, Instituto de Química/UNICAMP, Grupo de Espectrometria, Preparo de amostras e Mecanização-GEPAM, C. Postal 6154, 13084-971 Campinas, SP, Brazil. Electronic address: rachel.hauser.davis@gmail.com.
authors.forename: Rachel Ann
authors.initials: RA
authors.lastname: Hauser-Davis
authors.affiliation: UERJ, Instituto de Biologia Roberto Alcântara Gomes, Departamento de Bioquímica, Av. Manoel de Abreu 444, Maracanã, CEP 20550-900, Rio de Janeiro, RJ, Brazil.
authors.forename: Frederico Freire
authors.initials: FF
authors.lastname: Bastos
authors.affiliation: UERJ, Instituto de Biologia Roberto Alcântara Gomes, Departamento de Bioquímica, Av. Manoel de Abreu 444, Maracanã, CEP 20550-900, Rio de Janeiro, RJ, Brazil; Fundação Oswaldo Cruz, Instituto Oswaldo Cruz, Laboratório de Bioquímica de Proteínas e Peptídeos, 21040-360 Rio de Janeiro, RJ, Brazil.
authors.forename: Rafael Ferreira
authors.initials: RF
authors.lastname: Dantas
authors.affiliation: UERJ, Instituto de Biologia Roberto Alcântara Gomes, Departamento de Bioquímica, Av. Manoel de Abreu 444, Maracanã, CEP 20550-900, Rio de Janeiro, RJ, Brazil.
authors.forename: Santiago Alonso Leitão
authors.initials: SA
authors.lastname: Tobar
authors.affiliation: UERJ, Instituto de Biologia Roberto Alcântara Gomes, Departamento de Bioquímica, Av. Manoel de Abreu 444, Maracanã, CEP 20550-900, Rio de Janeiro, RJ, Brazil.
authors.forename: Jayme
authors.initials: J
authors.lastname: da Cunha Bastos Neto
authors.affiliation: National Institute of Science and Technology for Bioanalitics, Instituto de Química/UNICAMP, Grupo de Espectrometria, Preparo de amostras e Mecanização-GEPAM, C. Postal 6154, 13084-971 Campinas, SP, Brazil.
authors.forename: Vera Lucia Freire
authors.initials: VL
authors.lastname: da Cunha Bastos
authors.affiliation: Programa de Pós-Graduação em Biodiversidade Neotropical, Universidade Federal do Estado do Rio de Janeiro-UNIRIO, Av. Pasteur, 458 Urca, CEP 22290-240, Rio de Janeiro RJ, Brazil.
authors.forename: Roberta Lourenço
authors.initials: RL
authors.lastname: Ziolli
authors.affiliation: Instituto de Química/UNICAMP, Grupo de Espectrometria, Preparo de amostras e Mecanização-GEPAM, C. Postal 6154, 13084-971 Campinas, SP, Brazil; National Institute of Science and Technology for Bioanalitics, Instituto de Química/UNICAMP, Grupo de Espectrometria, Preparo de amostras e Mecanização-GEPAM, C. Postal 6154, 13084-971 Campinas, SP, Brazil.
authors.forename: Marco Aurélio Zezzi
authors.initials: MA
authors.lastname: Arruda
mesh_terms: D000818:Animals; D001646:Bile / Q000737:chemistry; D060125:Characiformes / Q000502:physiology*; D005978:Glutathione / Q000378:metabolism; D000860:Hypoxia / Q000503:physiopathology*; D015227:Lipid Peroxidation / Q000187:drug effects; D008099:Liver / Q000187:drug effects; D008668:Metallothionein / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D013053:Spectrophotometry; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D017392:Thiobarbituric Acid Reactive Substances; D008668:Metallothionein; D005978:Glutathione
keywords: Fish bile and liver; GSH; Hypoxia; Metallothionein; TBARS