Document Type : Research Paper
Nonylphenol (NP) is an endocrine disrupting chemical which has been shown to be able to modulate 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 immune parameters (IgM level and lysozyme activity) of Koi carp (Cyprinus the carpio carpio) in an attempt to expand the knowledge of the immune-reproductive system interactions. Fish were injected with ascending doses (10, 50,100 μg/g-1 body weight) of 4-nonylphenol (4-NP) and (2 μg/g-1 body mass) of 17-β-estradiol (E2) by vehicle during 3a weeks experiment. After 21 days, the fishes (180) were anesthetized, blood samples collected from their caudal vein, and after dissection, theywere grouped into male and female according to their gonadal characters. The results of plasmatic immune parameters measurement showed that 4-NP induced significant increase in IgM levels and lysozyme activity at 50μg/g -1 dosagewhile the their value decreased at higher doses of 4-NP (100 μg/g-1) compared with the control treatment (p<0.05). In addition,the treatment with 2 μg/g-1E2 injection, induced a significant decrease in IgM and lysozyme activity levels. These results indicated that 4-NP and E2 could potentially disturb the balance of immune system in immature koi carp with potential consequences for their endocrine interactions.