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Effects of 17ß-estradiol, 4-nonylphenol and PCB 126 on the estrogenic activity and phase 1 and 2 biotransformation enzymes in male sea bass (Dicentrarchus labrax)
Vaccaro, E.; Meucci, V.; Intorre, L.; Soldani, G.; Di Bello, D.; Longo, V.; Gervasi, P.G.; Pretti, C. (2005). Effects of 17ß-estradiol, 4-nonylphenol and PCB 126 on the estrogenic activity and phase 1 and 2 biotransformation enzymes in male sea bass (Dicentrarchus labrax). Aquat. Toxicol. 75(4): 293-305. dx.doi.org/10.1016/j.aquatox.2005.08.009
In: Aquatic Toxicology. Elsevier Science: Tokyo; New York; London; Amsterdam. ISSN 0166-445X, more
Peer reviewed article  

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Keywords
    Coenzymes; Marine fish; PCB; Sea bass; Sea bass; Transferases; Vitellogenesis; Dicentrarchus labrax (Linnaeus, 1758) [WoRMS]; Marine

Authors  Top 
  • Vaccaro, E.
  • Meucci, V.
  • Intorre, L.
  • Soldani, G.
  • Di Bello, D.
  • Longo, V.
  • Gervasi, P.G.
  • Pretti, C., correspondent

Abstract
    The endocrine system of wildlife is exposed to a wide variety of natural and man-made chemicals which may lead to damage to the reproductive system and other adverse effects, including alteration of drug-metabolizing enzymes. In the present study, the effects of in vivo exposure to a natural (17β-estradiol: E2) or a xenoestrogen (4-nonylphenol: NP) estrogen or an anti-estrogen (3,3′,4,4′,5-pentachlorobiphenyl: PCB 126) upon vitellogenin (VTG) synthesis and hepatic phase 1 and 2 enzymes have been investigated in adult male sea bass. By means of ELISA analysis with the use of polyclonal antibodies prepared against VTG purified from E2-treated sea bass, we assessed the time course and sensitivity of VTG induction in the plasma of sea bass treated with E2 at 0.1, 0.5, 2.5 and 5.0 mg/kg doses or NP at 5.0 or 50 mg/kg doses, respectively. Sea bass sensitivity to this induction was found to be similar to that of other fish species, but with a delay in maximal response. E2 treatment also caused a selective time- and dose-dependent inhibition of hepatic CYP1A-linked EROD and phase 2 glutathione S-transferase (GST) activities, without affecting the activity of CYP3A-linked 6β-testosterone hydroxylase, (ω)- and (ω-1)-lauric acid hydroxylases or phase 2 DT-diaphorase. A similar selective inhibition on CYP1A was also observed in fish treated with 50 mg/kg NP. The results regarding CYP1A and CYP3A were also confirmed by Western blot analysis. When the sea bass were treated with either 10 or 100 μg/kg PCB 126, an AhR ligand not yet tested in vivo in fish to assess its anti-estrogenicity, a modest and selective induction of EROD and DT-diaphorase activities was observed. Interestingly, both these activities were recovered to their control levels in sea bass co-treated with 0.5 mg/kg E2 and 10 or 100 μg/kg PCB 126, probably through a cross-talk mechanism between the estrogen receptor and AhR or other transcription factors that regulate the expression of these enzymes. Furthermore, it was demonstrated that PCB 126 possesses a potent anti-estrogenic activity in the sea bass in vivo as it inhibited the E2-induced VTG synthesis with an IC50 of 28 μg/kg. The results of this study suggest that the exposure of fish to xenoestrogens or anti-estrogens may alter, in addition to various physiological processes, the expression of specific CYPs and phase 2 enzymes, thereby reducing the capability of their detoxication system.

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