Effects of Sulfamethazine on the Non-Specific Immune Enzyme Activities of Fenneropenaeus chinensis

Abstract:

Shrimp production has been a well-developed pillar of the aquaculture industry in China. Fenneropenaeus chinensis, one of highly valuable shrimp species, was mainly raised in the Bohai Sea and the Yellow Sea in North China. Antimicrobials are most frequently applied during intensive aquacultures to prevent or cope with disease outbreaks. However, antimicrobials may also have toxic effects on cultured animals such as immunosuppression. To better understand the mechanisms, we measured activities of superoxide dismutase (SOD), alkaline phosphatase (AKP), lysozyme (LZM), and phenoloxidase (PO) in serum upon the treatment with sulfamethazine (SM2) at different concentrations. It was found that SM2 significantly enhanced SOD activity at 50 mg/kg, whereas inhibited SOD at 150 mg/kg. At 100 mg/kg, SM2 first boosted SOD activity in the first 2 days and then suppressed it from Day 3 of treatment compared to the control group. Treated with 50 mg/kg SM2, the activity of AKP was inhibited from Day 2 of treatment till Day 2 after the treatment, followed by a recovery to the control level. When the SM2 concentration was 100 mg/kg, the AKP activity was elevated to a peak value on Day 5 of the treatment and then dropped back to the control level. In the treatment with 150 mg/kg SM2, AKP activity altered in the same pattern as the medium concentration group. SM2 had inhibitive effects on LZM at 50, 100, and 150 mg/kg. In spite of the concentrations of SM2, the PO activity showed the same trend that it rose to a higher level than the control followed by a decrease. The non-specific immunity was inhibited by SM2 at 150 mg/kg. Therefore, the dosage of antibiotics should be carefully evaluated to ensure healthy aquaculture of shrimp.