Co-exposure to nTiO₂ impairs arsenic metabolism and affects antioxidant capacity in the marine shrimp Litopenaeus vannamei

Abstract

Aquatic animals are vulnerable to arsenic (As) toxicity. However, rarely does a contaminant occur alone in the aquatic environment. For this reason, this study was conducted to evaluate whether titanium dioxide nanoparticles (nTiO₂) can interfere with the effects induced by As in Litopenaeus vannamei. Arsenic accumulation and metabolic capacity; expression and enzymatic activity of GSTΩ (glutathione-S-transferase omega isoform); antioxidant responses such as GSH, GR, and GST (reduced glutathione levels, glutathione reductase, and glutathione-S-transferase activity, respectively); and lipid peroxidation in the gills and hepatopancreas of shrimp were evaluated. The results are summarized as follows: (1) higher accumulation of As occurred in both tissues after exposure to As alone; (2) co-exposure to nTiO₂ affected the capacity to metabolize As; (3) GSTΩ gene expression was not modified, but its activity was decreased by co-exposure to both contaminants; (4) As alone increased the GSH levels in the hepatopancreas, and co-exposure to nTiO₂ reduced these levels in both tissues; (5) a decrease in the GST activity in the gills occurred with all treatments; (6) in the gills, GR activity was increased by As, and nTiO₂ reversed this increase, whereas in the hepatopancreas co-exposure inhibited enzyme activity; (7) only in the hepatopancreas lipid damage was observed when animals were exposed to As or nTiO₂ but not in co-exposure. The results showed that the As induces toxic effects in both tissues of shrimp and that co-exposure to nTiO₂ can potentiate these effects and decrease the capacity to metabolize As, favoring the accumulation of more toxic compounds.

Keywords:

• Titanium dioxide nanoparticles
• GSTΩ
• antioxidant responses
• arsenic metabolization
• Litopenaeus vannamei

Acknowledgements

The authors wish to thank CNPq for financial support (MCTI/CNPq process n°17/2011) and CAPES. Lucas Cordeiro is a graduate fellow at Fundação de Amparo à Pesquisa do Rio Grande do Sul (FAPERGS). Silvana Manske Nunes and Larissa Müller are graduate fellows from Cordenação de aperfeiçoamento de Pessoal de nível superior (CAPES). Luiza Kist is a recipient of a CAPES/PNPD fellowship. José M. Monserrat, Wilson Wasielesky, and Maurício Bogo are research fellows at CNPq. Juliane Ventura-Lima and José M. Monserrat are members of the nanotoxicology network “Nanotoxicologia ocupacional e ambiental: subsídios científicos para estabelecer marcos regulatórios e avaliação de riscos” (CNPq, Proc. 552131/2011–3).

Disclosure statement

No potential conflict of interest was reported by the authors.