Induction of vitellogenin synthesis in immature male yellowfin seabream (Acanthopagrus latus) exposed to 4-nonylphenol and 17β-estradiol

In the present study, the effects of xenoestrogen 4-nonylphenol (4-NP) and 17 beta-estradiol (E2) on the synthesis of vitellogenin (VTG) in immature male yellowfin seabream (Acanthoparus latus) were assessed to determine the potential use of this species as a biological model for studying endocrine disrupters in the Musa estuary in southern seawaters of Iran. A total number of 104 fish were injected by 10, 50, 100, 150 and 200 mu g g(-1) week(-1) of 4-NP and 2 mu g g(-1) week(-1) of E2, and their blood plasma was obtained for biochemical analysis on days 0, 7 and 14. The hepatosomatic index (HSI) of each fish was also recorded at each sampling time. The results showed that 4-NP significantly induced VTG synthesis in A. lotus, which was detected by gel electrophoresis as two major protein bands (similar to 210 and 191 KDa). The induction of VTG was also determined indirectly by measuring the alkali-labile phosphate, total plasma calcium and protein. All of these VTG indicators significantly increased in the plasma of 4-NP- and E2-treated fish. Meanwhile, a significant dose-dependent increase was observed in HSI, indicating the activation of hepatic VTG production in 4-NP- and E2-injected fish. Furthermore, the plasma alanine aminotransferase and aspartate aminotransferase concentrations significantly increased in 4-NP-treated fish, presumably reflecting a situation of hepatic tissue damage due to 4-NP toxicity. Based on the results, it is suggested that A. lotus could be used successfully as a model species for future studies of endocrine disrupting contaminants in the Musa estuary.