Endocrine alteration of 4-nonylphenol: in vivo studies of inter-species differences

Abstract

Three kinds of juvenile marine fish (Paralichthys olivaceus, Sebastes schlegeli, and Pagrus major) were continuously exposed to 4-nonylphenol (4-NP) at concentrations of 10, 50 and 100 ug/ L for 7 days using an intermittent flow-through dosing system. Plasma vitellogenin (VTG) and hepatic VTG mRNA were determined in a group of fish sampled during exposure phase. In two fish species (P. olivaceus and S. schlegeli), VTG mRNA apparently increased in four days of exposure. VTG proteins in P. olivaceus and P. major were induced at 50 ug/L from the fourth day of exposure and S. schlegeli was induced at 20 ug/L. Plasma concentrations of testosterone in the exposure group were not significantly different from those in the control group. However, plasma estradiol-17β concentrations of the female increased in P. olivaceus and S. schlegeli after 4-NP exposure. Our results suggest that 4-NP may disrupt the vitellogenesis system of immature fish by acting directly on vitellogenesis and steroidogenesis. Immature S. schlegeli exposed with 4-NP were more sensitive than P. olivaceus and P. major. There are obviously large inter-species differences in response of fish to 4-NP.