Hypoxia acclimation protects against oxidative damage and changes in prolactin and somatolactin expression in silver catfish (Rhamdia quelen) exposed to manganese

• Published in: Aquatic toxicology 2014-12, Vol.157, p.175-185
• Main Authors: Dolci, G.S., Vey, L.T., Schuster, A.J., Roversi, Kr, Roversi, K., Dias, V.T., Pase, C.S., Barcelos, R.C.S., Antoniazzi, C.T.D., Golombieski, J.I., Glanzner, W.G., Anezi Junior, P.A., Gonçalves, P.B.D., Nunes, M.A.G., Dressler, V.L., Baldisserotto, B., Burger, M.E.
• Format: Article
• Language: English
• Subjects: Acclimatization; Adenosine Triphosphatases - metabolism; Agnatha. Pisces; Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; Catalase - metabolism; Catfishes - metabolism; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on vertebrates; Enzyme Activation - drug effects; Fish Proteins - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - drug effects; Gills - metabolism; Glycoproteins - genetics; Hormesis; Hypoxia - metabolism; Manganese; Manganese - toxicity; Moderate hypoxia; Na+/K+-ATPase; Oxidation-Reduction; Oxidative stress; Pituitary Gland - drug effects; Pituitary Hormones - genetics; Pituitary hormones expression; Prolactin - genetics; Rhamdia quelen; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Water Pollutants, Chemical - toxicity
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2014.10.015

•Silver catfish were acclimated in hypoxia and posteriorly exposed to Mn.•Hypoxia acclimation decreased Mn accumulation in vital organs of silver catfish.•Hypoxia acclimated fish showed reduced oxidative damages in different vital organs.•Hypoxia acclimation prevents molecular changes in pituitary hormones.•Hypoxia acclimation reduces Mn toxicity and oxidative damages, possibly by hormesis. The aim of this study was to assess the Mn toxicity to silver catfish considering Mn accumulation and oxidative status in different tissues, as well as pituitary hormone expression after acclimation to hypoxia. Silver catfish acclimated to hypoxia for 10 days and successively exposed to Mn (9.8mgL−1) for an additional 10 days exhibited lower Mn accumulation in plasma, liver, kidneys and brain and prevented the hematocrit decrease observed in the normoxia group. Hypoxia acclimation also modified Mn-induced oxidative damage, which was observed by lower reactive species (RS) generation in gills and kidneys, decreased lipid peroxidation (LP) levels in gills, liver and kidneys and decreased protein carbonyl (PC) levels in liver, kidneys and brain. Manganese accumulation showed positive correlations with LP levels in gills and kidneys, as well as with PC levels in gills, liver and brain. In addition, hypoxia acclimation and Mn exposure increased catalase (CAT) activity in gills and kidneys and Na+/K+-ATPase activity in gills, liver and brain. Silver catfish that were acclimated under normoxia and exposed to Mn displayed increased pituitary prolactin (PRL) and decreased somatolactin (SL) expression. Interestingly, hypoxia acclimation prevented hormonal fluctuation of PRL and SL in fish exposed to Mn. These findings indicate that while the exposure of silver catfish to Mn under normoxia was related to metal accumulation and oxidative damage in tissues together with endocrine axis disruption, as represented by PRL and SL, hypoxia acclimation reduced waterborne Mn uptake, thereby minimizing oxidative damage and changes in hormonal profile. We hypothesized that moderate hypoxia is able to generate adaptive responses, which may be related to hormesis, thereby ameliorating Mn toxicity to silver catfish.