Effects of endocrine disruption by 4-nonylphenol ethoxylate on the growth performance and immune response of female and male immature koi carp (Cyprinus carpio carpio)

Nonylphenol (NP) is an endocrine disrupting chemical which has been shown to be able tomodulate endocrine system of various organisms by different mechanisms. The objective of this study was to investigate the potential effects of 4-NP and 17-β - estradiol (E2) on the immune parameters (IgM levels and lysozyme activity) of the teleost Koi carp (Cyprinus carpio carpio) for a better understanding of the immune-reproductive system interactions. The experimental fishes were injected with ascending doses (10, 50,100 μgg-1 body weight) of 4- nonylphenol (4-NP) and (2 μgg-1 body mass) of 17-β-estradiol (E2) or vehicle during 3 weeks. After 21 days, the fishes (180) were anesthetizedand their blood samples were collected from caudal vein, then they were dissected and sexually separated by gonad characters. The measurement of immune parameters in plasma showed that 4-NP induced significant increase in the IgM levels and lysozyme activity at dose of 50 μgg-1 while the levels of these parameters in the higher doses (100 μgg-1) decreased compared with the control group (p<0.05). In addition the treatment, with 2 μgg-1 E2 significantly decreased both the IgM levels and lysozyme activity after 21 days of injection. These results indicated that 4-NP and E2 could lead to disturb the balance of immune system with potential consequences for immature koi carp.