Toxic effects of nitenpyram on antioxidant enzyme system and DNA in zebrafish (Danio rerio) livers

• Nitenpyram could induce antioxidant enzyme response and DNA damage in zebrafish livers on days 7, 14, 21 and 28.
• The activity of SOD and CAT was significantly inhibited in most exposure period, which is opposed to GST activity.
• ROS generation and MDA level were accordingly enhanced at 7 d, 14 d, 21 d and 28 d.
• DNA damage increased in the whole experiment periods (7 d, 14 d, 21 d, and 28 d).

Nitenpyram is one of the most commonly used neonicotinoid pesticide worldwide and was found to be toxic to non-target aquatic organisms. Therefore, the purpose of this study was to investigate the oxidative stress, changes in the detoxifying system and DNA damage in zebrafish induced by nitenpyram. In the present study, zebrafish (Danio rerio) were exposed to four concentrations (0.6, 1.2, 2.5, and 5.0 mg L−1) for 28 d and then sampled in triplicate on days 7, 14, 21 and 28. Superoxide dismutase (SOD) and catalase (CAT) activities were dramatically inhibited at most exposure times compared with the control group, except SOD at low concentration (0.6 mg L−1) of nitenpyram and CAT on day 21. This difference is due to the excess reactive oxygen species (ROS) produced and increased malondialdehyde (MDA) content in zebrafish livers. The activity of glutathione S-transferase (GST) increased in in the treatment groups at a higher concentration compared with the control group. We found that nitenpyram exposure could affect the antioxidant enzymes and DNA damage in the exposed zebrafish livers. Additionally, the changes in the antioxidant enzyme activities could be an adaptive response protecting against the toxicity induced by nitenpyram.

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