Evidências de desregulação endócrina causada pela exposição aquática ao alumínio e ao manganês em Astyanax bimaculatus (Linnaeus, 1758) / Evidences of endocrine disruption caused by aquatic exposure to aluminum and manganese in Astyanax bimaculatus (Linnaeus, 1758)

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

21/09/2012

RESUMO

Metals such as Aluminum (Al) and Manganese (Mn) are found in nature as well as in industrial effluents, and can be toxic to aquatic biota, with endocrine disrupting effects, e.g. for fish, which can affect the reproductive performance of a species. Rivers and tributaries of São Paulo State, even in theoretically preserved areas, have shown an increase in the supply of these metals in concentrations greater than allowed by law, and the consequence for the fish is poorly understood. In this study, toxicity tests were designed for acute aquatic exposure (96 hours) to Al and Mn, in isolated and synchronous forms, in vitellogenic females of Astyanax bimaculatus, a teleost fish species. This exposure period was followed by a period in clean water (96 hours) to assess the possibility of recovery of toxic effects promoted by these metals, evaluating the following parameters: relative fecundity (FR), bioconcentration potential of these metals, plasma concentration of Estradiol (E2), 17α hydroxyprogesterone (17α -OHP), Cortisol (CT), triiodothyronine (T3), thyroxine (T4) and mRNA gene expression of βFSH and βLH. Five experimental groups were established: Control at neutral pH, acidic pH, Al, Mn and synchronic exposure to Al and Mn. The results showed that acidic pH and Al reduced FR with no recovery effect. Al was mainly bioconcentrate in gills, liver and brain, whereas Mn was mainly bioconcentrate in gills, but with less intensity than Al. When exposed synchronously, Mn potentiated the effects of Al bioconcentration, causing a reduction in the plasma levels of E2 and 17α-OHP, for this progestogen only to Mn exposure, both, in isolated and synchronous exposure. But recovery was not observed in E2 levels. Both metals, in isolated exposure caused a reduction in plasma CT, but no change was recorded in synchronous exposure. Likewise, both metals induced reduction in plasma T4 levels, including synchronous exposure, whereas T3 levels were differently altered in each metal exposure group. Possibly the effects on thyroid hormones have reflected a response to endocrine modulation, whereas steroids showed endocrine disrupting effects in na antiesteroidogenic way. No effects were observed in mRNA βLH gene expression and it was not possible to achieve βFSH results, although the primers were designed especially for A. bimaculatus and have worked properly in the preparation of the standard curve for qRT - PCR. The results found in vitellogenic A. bimaculatus females may be related to the type of exposure and interaction, which were variable between Al and Mn ions.

ASSUNTO(S)

alumínio aluminum desregulador endócrino ecotoxicologia ecotoxicology endocrine disruptor fish manganês manganese metais metals peixes reprodução reproduction

ACESSO AO ARTIGO

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