title: Could hypoxia acclimation cause morphological changes and protect against Mn-induced oxidative injuries in silver catfish (Rhamdia quelen) even after reoxygenation?
abstract: Exposure to hypoxia has shown beneficial adjustments in different species, including silver catfish (Rhamdia quelen), especially in situations of aquatic contamination with pollutants such as manganese (Mn). Considering that hypoxia is seasonal in the natural aquatic environment, we decided to assess whether these adaptive mechanisms could be maintained when reoxygenation is established. Silver catfish acclimated to moderate hypoxia (∼3 mg L-1, 41% O2saturation) for 10 days and subsequently exposed to Mn (∼8.1 mg L-1) for additional 10 days displayed lower (47%) Mn accumulation in the gills, and it was maintained (62.6%) after reoxygenation, in comparison to normoxia. Oxidative status in the gills allowed us to observe increased reactive species (RS) generation and protein carbonyl (PC) level together with decreased mitochondrial viability induced by Mn under normoxia. Inversely, while hypoxia per se was beneficial on RS generation and PC level, this acclimation was able to minimize Mn toxicity, as observed by the minor increase of RS generation and the minor reduction of mitochondrial viability, together with decreased PC level. Interestingly, after reoxygenation, part of the protective influences observed during hypoxia against Mn toxicity were maintained, as observed through a lower level of PC and higher mitochondrial viability in relation to the group exposed to Mn under normoxia. Only groups exposed to Mn under hypoxia showed increased activity of both catalase (CAT) and Na+/K+-ATPase in the gills, but, while CAT activity remained increased after reoxygenation, Na+/K+-ATPase activity was decreased by Mn, regardless of the oxygen level. Based on these outcomes, it is possible to propose that environment events of moderate hypoxia are able to generate rearrangements in the gills of silver catfish exposed to Mn, whose influence persists after water reoxygenation. These responses may be related to the adaptive development, reducing Mn toxicity to silver catfish. Moderate hypoxia generates rearrangements in the gills of Silver catfish, exerting beneficial and persistent protection against Mn toxicity.
authors.affiliation: Programa de Pós Graduação em Farmacologia - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil.
authors.forename: G S
authors.initials: GS
authors.lastname: Dolci
authors.affiliation: Departamento de Fisiologia e Farmacologia - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil.
authors.forename: H Z
authors.initials: HZ
authors.lastname: Rosa
authors.affiliation: Programa de Pós Graduação em Bioquímica Toxicológica - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil.
authors.forename: L T
authors.initials: LT
authors.lastname: Vey
authors.affiliation: Programa de Pós Graduação em Farmacologia - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil.
authors.forename: C S
authors.initials: CS
authors.lastname: Pase
authors.affiliation: Programa de Pós Graduação em Farmacologia - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil.
authors.forename: R C S
authors.initials: RCS
authors.lastname: Barcelos
authors.affiliation: Programa de Pós Graduação em Farmacologia - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil.
authors.forename: V T
authors.initials: VT
authors.lastname: Dias
authors.affiliation: Programa de Pós-Graduação em Biodiversidade Animal - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil.
authors.forename: L
authors.initials: L
authors.lastname: Loebens
authors.affiliation: Programa de Pós-graduação em Química - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil.
authors.forename: P
authors.initials: P
authors.lastname: Dalla Vecchia
authors.affiliation: Programa de Pós-graduação em Química - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil.
authors.forename: C A
authors.initials: CA
authors.lastname: Bizzi
authors.affiliation: Programa de Pós Graduação em Farmacologia - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil; Departamento de Fisiologia e Farmacologia - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil.
authors.forename: B
authors.initials: B
authors.lastname: Baldisserotto
authors.affiliation: Programa de Pós Graduação em Farmacologia - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil; Departamento de Fisiologia e Farmacologia - UFSM, Universidade Federal de Santa Maria (UFSM), Av. Roraima nº 1000, Cidade Universitária, Camobi, Santa Maria, 97105-900, RS, Brazil. Electronic address: marilise.burger@ufsm.br.
authors.forename: M E
authors.initials: ME
authors.lastname: Burger
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D002374:Catalase / Q000378:metabolism; D002397:Catfishes / Q000378:metabolism*; D005880:Gills / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D000860:Hypoxia / Q000378:metabolism* / Q000503:physiopathology; D008345:Manganese / Q000633:toxicity*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D010100:Oxygen / Q000378:metabolism*; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D017392:Thiobarbituric Acid Reactive Substances; D014874:Water Pollutants, Chemical; D008345:Manganese; D002374:Catalase; D010100:Oxygen
keywords: Histological analyses; Hormesis; Mitochondrial viability; Moderate hypoxia; Oxidative stress; Rhamdia quelen