RESUMO
In this study, effects of parabens on antioxidant defenses and oxidative damages in gills and liver of Nile tilapia (Oreochromis niloticus) were evaluated. Adult Nile tilapia were exposed to methyl, ethyl, propyl, butyl and benzylparaben and a mixture of methyl and propylparaben for 6 and 12 days. The biomarkers analyzed were superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), total glutathione (GSH-t) and lipid peroxidation measured by malondialdehyde (MDA) content. Results indicated that exposure to parabens caused biochemical changes in gill and liver cells, which in turn modulated enzymatic and non-enzymatic antioxidants in Nile tilapia. SOD, GPx and GR activity significantly increased in gills and liver after exposure to most parabens. CAT activity had little (liver) or no alteration (gills) in this fish species after treatment with parabens. GSH-t content in liver decreased after 6 days of exposure to parabens, but after 12 days, GSH-t levels increased in liver in all treatments, indicating an antioxidant adaptation to exposure to sublethal doses of parabens. Regarding the MDA levels, no alterations were observed in gills compared to control and in liver the MDA content was reduced after 12d of exposure to ethylparaben, butylparaben and paraben mixture, indicating no lipid peroxidation in the analyzed tissues. Our results demonstrate parabens-induced adaptive responses in fish, which were important in the protection against oxidative damages.
Assuntos
Ciclídeos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Parabenos/toxicidade , Animais , Biomarcadores/metabolismo , Catalase/metabolismo , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Glutationa Redutase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Malondialdeído/metabolismo , Superóxido Dismutase/metabolismo , Testes de Toxicidade AgudaRESUMO
Atualmente, com a crescente contaminação dos ecossistemas aquáticos, muitos compostos, como pesticidas e hidrocarbonetos,são lançados de forma indevida em corpos dágua. Estudos relacionando a exposição de poluentes, individualmente,com variações bioquímicas são abundantes na literatura. Entretanto, ainda são poucos os voltados às misturas complexas.Sendo assim, o objetivo do presente estudo foi analisar se a mistura diazinon e benzo[a]pireno pode afetar as atividadesbioquímicas de biomarcadores clássicos, tais como acetilcolinesterase (AChE), carboxilesterase (CbE), catalase (CAT), glutationaperoxidase (GPx) e glutationa S-transferase (GST) em Tilápias do Nilo (Oreochromis niloticus) e comparar os efeitosnos sistemas enzimáticos quando estão expostos à mistura e aos compostos separadamente. Foi medida a atividade dasenzimas em brânquias e fígados de Tilápia do Nilo após 2 e 7 dias de exposição ao Diazinon (0,5 mg/L) e ao benzo[a]pireno (1,0 mg/L) individualmente e em mistura. Os resultados mostraram que no grupo mistura do fígado após 7 dias deexposição, o benzo[a]pireno aumentou a ação inibidora do Diazinon na atividade da enzima GST. Isso indica que a toxicidadedas interações ambientais entre pesticida e hidrocarboneto policíclico aromático pode apresentar efeito sinérgico.Desse modo, é importante levar em conta esse fator, pois irá auxiliar na compreensão de resultados obtidos em estudosde campo, como em um monitoramento ambiental.
Currently, with the growing contamination of aquatic ecosystems, many compounds, such as pesticides and hydrocarbons,are improperly released into rivers and lakes. Studies about the exposure of single pollutants causing biochemical variationsare abundant in the literature. However, there are few studies focused on the biological effects of complex mixtures.The aim of this investigation was to evaluate whether mixture diazinon and benzo[a]pyrene can affect the biochemicalactivities of classic biomarkers such as acetylcholinesterase (AChE), carboxylesterase (CbE), catalase (CAT), glutathioneperoxidase (GPx) and glutathione S-transferase (GST) in Nile tilapia and compare the effects on enzymatic systems of theexposure to a mixture of compounds and the effects observed when they are exposed separately. We measured the activityof enzymes in gills and liver of Nile Tilapia (Oreochromis niloticus) after 2 and 7 days of exposure to Diazinon (0.5 mg/L)and benzo[a]pyrene (1.0 mg/L) individually and in mixture. The results showed that in the mixture group after 7 days ofexposure, the benzo[a]pyrene increased the inhibitory action of Diazinon in GST enzyme activity, in liver tissue. This indicatesthat the toxicity of the interactions between pesticide and polycyclic aromatic hydrocarbon may show synergisticeffect. These results suggest the importance of studies with mixture of compounds, because these data will help to understandthe results obtained in field studies, such as those from environmental monitoring.