Influence of oestradiol on induction of EROD activity in roach ( Rutilus rutilus L.)

The induction of ethoxyresorufin- O-deethylase (EROD) activity by β-naphthoflavone was examined in roach, Rutilus rutilus, administered with oestradiol-17β and in untreated fish. Constitutive levels of EROD activity were low and not significantly affected by steroid treatment but oestradiol significantly suppressed the induction response. EROD induction following environmental exposure to PAHs is therefore likely to be reduced in female fish, particularly during the spawning season. However, the response should still be of a sufficient magnitude to clearly demonstrate the presence of these xenobiotics in the freshwater environment.