The effects of subchronic exposure to ciprofloxacin on zebrafish (Danio rerio).

OBJECTIVES: The aim of this study was to assess the impact of ciprofloxacin in Danio rerio on growth, on the development of histopathological changes in selected organs (gills, kidney, liver), and on the activity of some oxidative stress markers during a 28-day toxicity test.

METHODS: Juvenile growth tests were performed on D. rerio according to OECD guideline No. 215. Fish at the age of 30 days were exposed for 28 days to a range of concentrations of ciprofloxacin (0.7 μg x L(-1)--environmental concentration, 100, 650, 1100 and 3 000 μg x L(-1)).

RESULTS: There were no significant differences between the specific growth rates of fish from the test groups and from the control group. Histopathological examination revealed no pathological changes in organs of fish exposed to any ciprofloxacin concentration. The activity of glutathione S-transferase increased at the ciprofloxacin concentrations of 0.7 and 100 μg x L(-1) compared to the control. A significant decrease in glutathione reductase activity was obtained in fish exposed to ciprofloxacin at 1100 and 3000 μg x L(-1); a significant decrease in glutathione peroxidase activity was also found, but at all tested concentrations except for 100 μg x L(-1). A decrease in the concentration of thiobarbituric acid reactive substances was noted only at 100 μg x L(-1) compared to the control.

CONCLUSIONS: According to our results, all tested concentrations of ciprofloxacin, including the environmental concentration, had an influence on oxidative stress markers and detoxifying enzymes in exposed fish, but did not affect fish growth or cause the development of histopathological changes in the fish organism.

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