Oxidative stress, neurotoxicity, and metallothionein (MT) gene expression in juvenile rock fish Sebastes schlegelii under the different levels of dietary chromium (Cr6+) exposure

• The chromium exposure induced the significant alterations in antioxidant responses.
• The AChE was considerably inhibited by the chromium exposure.
• The MT gene expressionwas substantially caused by the chromium exposure.

Juvenile Sebastes schlegelii were exposed for 4 weeks with the different levels of dietary chromium (Cr6+) concentration (0, 30, 60, 120 and 200 mg/kg). The superoxide dismutase (SOD) activity, glutathione S-transferase (GST) activity, and glutathione (GSH) level of liver and gill were evaluated after 4 weeks exposure. The SOD and GST activity of liver and gill was significantly increased in the concentration of 240 mg/kg after 2 weeks and over 120 mg/kg after 4 weeks, whereas a considerable decrease in the concentration of 240 mg/kg after 2 weeks and over 120 mg/kg after 4 weeks was observed in the GSH levels of liver and gill. In neurotoxicity, AChE activity was significatly inhibited in brain in the concentration of 240 mg/kg after 2 weeks and over 60 mg/kg after 4 weeks and muscle in the concentration of 240 mg/kg after 2 weeks and over 120 mg/kg after 4 weeks. Metallothionein (MT) gene in liver was considerably increased over 120 mg/kg after 2 weeks and at 30, 120, and 240 mg/kg after 4 weeks by dietary chromium exposure. The results indicate that dietary Cr exposure over 120 mg/kg can induce substantial alterations in antioxidant responses, AChE activity and MT gene expression.