INFLUENCE OF ESTRADIOL ON INDUCTION OF EROD ACTIVITY IN ROACH (RUTILUS-RUTILUS L)

The induction of ethoxyresorufin-O-deethylase (EROD) activity by beta- naphthoflavone was examined in roach, Rutilus rutilus, administered wi th oestradiol-17 beta and in untreated fish. Constitutive levels of ER OD activity were low and not significantly affected by steroid treatme nt but oestradiol significantly suppressed the induction response. ERO D induction following environmental exposure to PAHs is therefore like ly to be reduced in female fish, particularly during the spawning seas on. However, the response should still be of a sufficient magnitude to clearly demonstrate the presence of these xenobiotics in the freshwat er environment.