Comparison of the effects of copper oxide nanoparticles (CuO-NPs) and copper (II) sulfate on oxidative stress parameters in rainbow trout hatchlings (Oncorhynchus mykiss)

Abstract

Nanoparticles of copper oxide, released uncontrollably into the environment, pose a threat to living organisms. One of the mechanisms of their toxicity is the induction of oxidative stress, contributing to the disruption of antioxidant mechanisms. The aim of the present study was to assess the degree and toxic dose of copper oxide nanoparticle (CuO-NPs) associated with the induction of oxidative stress and compare them to the toxicity of copper sulfate (VI) (CuSO4) by measuring the expression of genes encoding some key enzymes involved in protection against oxidative stress: glutathione peroxidase (gpx), cytochrome P450 (cyp1a), heat shock protein (hsp70) and superoxide dismutase (sod). Hatchlings of rainbow trout (Oncorhynchus mykiss) were used as biological material. The test individuals were exposed for 2 hours to CuO-NPs and CuSO4 in the concentration range of 4–256 mg dm−3. Individuals exposed to all concentrations of CuO-NPs showed an increase in the expression of gpx, cyp1a and hsp70 genes, and a decrease in sod gene expression, while the hatchlings exposed to CuSO4 exhibited an increase in the expression of all genes. The expression of hsp70 and sod genes in the hatchlings exposed to CuSO4 was higher than in the CuO-NP treatment, while the expression levels of gpx and cyp1a were similar. Based on the obtained results, potentially higher toxicity of CuSO4 was observed in the hatchlings of Oncorhynchus mykiss. However, the elevated expression of gpx, cyp1a and hsp70 after the exposure to CuO-NPs, indicates toxicity via oxidative stress. The decrease (sod in hatchlings exposed to CuO-NPs) or increase of gene expression was not dose-dependent. The presented study confirms a need for further research regarding the toxicity of metal nanoparticles to aquatic organisms and the necessity for monitoring the release of CuO-NPs into the aquatic environment.

Keywords

• Oncorhynchus mykiss
• copper oxide nanoparticles
• copper (II) sulfate
• oxidative stress
• aquatic toxicology
• ecotoxicology