Nanostructured environmental multi-stressors effects on a Neotropical teleost: neurotoxicity, antioxidant metabolism and defense mechanisms

Abstract

Manufacture and use of carbon nanoparticles (NP) are increasing exponentially, which contributes for its presence in the aquatic environment. Those NP can be used to enhance central nervous system permeation to drugs of interest, overcoming the blood-brain barrier. Water bodies also host other kinds of pollutants, such as organophosphorus insecticides (OP), highly used in agriculture. Studies regarding xenobiotic interaction effects on aquatic biota are scarce, especially in tropical species, notwithstanding its importance and great ecological relevance. This proposal aims to evaluate the effects of a carbon NP, graphene oxide (GO), individually and associated to a broadly used organophosphorus biocide, chlorpyrifos, in pacu (Piaractus mesopotamicus), unraveling the toxicity mechanisms of this xenobiotic complex mixture. In order to achieve this objective, the following experiments are proposed: 1) Evaluation of LC50;96h of GO to P. mesopotamicus; 2) Sub-lethal exposure to GO and chlorpyrifos (individually and combined) and assessment of biochemical biomarkers: brain acethylcholinesterase activity and hepatic antioxidant metabolism (reactive oxygen species generation and activity of catalase, superoxide dismutase and glutathione peroxidase); 3) In vitro assessment of P. mesopotamicus hepatocyte P-glycoprotein (P-gp) activity in the presence of GO and chlorpyrifos. The results obtained in this study will provide unprecedented information regarding GO toxicity to a Neotropical teleost, individually and associated to a OP biocide; supporting regulatory efforts concerning safe levels of NP to the aquatic biota, besides elucidating P-gp roles in the toxicity mechanisms arising from these multi-stressors exposure.