The effect of sulfamethoxazole on oxidative stress indices in zebrafish (Danio rerio).

The aim of this study was to assess the impact of sulfamethoxazole (SMX) on oxidative stress indices in zebrafish (Danio rerio). The test was completed after 14 days. The tested concentrations were 50, 100 and 500 µg/L of SMX. Glutathione peroxidase, glutathione reductase, glutathione S-transferase and lipid peroxidation were investigated to determine the effects of SMX on oxidative stress in zebrafish. Lipid peroxidation gradually increased slightly (but non-significantly) at all tested concentrations during the test as compared to the control. The evaluation of oxidative stress biomarkers showed no significant changes in the activity of antioxidant enzymes in any experimental group exposed to SMX as compared to the control. The gradual increase in lipid peroxidation after 3 and 14 days in the SMX treated groups as compared to the control group indicates increasing cell membrane damage.

Oxidative stress induced by fluoroquinolone enrofloxacin in zebrafish (Danio rerio) can be ameliorated after a prolonged exposure.

The purpose of our experiment was to evaluate the effect of enrofloxacin on biotransformation, oxidative stress and mRNA expression of related genes in fish as a non-target organisms. Zebrafish (Danio rerio) juveniles were treated with enrofloxacin at concentrations of 5, 10 and 500 µg/L for 14 days. A three-day-long test caused changes of catalytic activity of glutathione peroxidase and glutathione-S-transferase. Moreover, lipid peroxidation was observed at the highest concentration. No significant changes either in catalytic activity of antioxidant enzymes or elevated lipid peroxidation were observed from sampling day 7 on. mRNA expression of genes encoding antioxidant enzymes was also not affected by enrofloxacin after a 14-day exposure. This suggests the ability of D. rerio juveniles to adapt to enrofloxacin in a short time period. Moreover, enrofloxacin was not shown to affect collagen, cathepsin K, optic atrophy 1 and pyruvate kinase L/R mRNA expression in this study.