Cytochrome P450 1A induction in gudgeon (Gobio gobio): Laboratory and field studies

The induction of cytochrome P450 1A was studied in gudgeon (Gobio gobio), a common European cyprinid, using both farm-raised and field-caught fish. Th e effects of sex, reproductive status and past exposure to xenobiotics were assessed. When exposed to beta-naphthoflavone (bNF), reared gudgeon showed a dose-dependent increase of EROD activity with a plateau observed at dose s from 20 mg kg(-1) (females) and 5 mg kg(-1) (mares). The sexual differenc e in EROD activity was related to the gonadosomatic index (GSI) of the fema le whatever the level of induction. Dose and sex effects were confirmed by the immunodetection of CYP1A protein. More than 1 month was necessary for E ROD activity to decrease to baseline levels. A second bNF injection after 3 2 days gave similar levels of induction, suggesting that EROD induction by bNF was not impaired by a pretreatment. Wild fish were brought from two sit es in the Rhone river basin: a low contaminated site (Ain) and a highly con taminated site (Rhone). Wild gudgeon were highly induced by bNF in laborato ry conditions, except males from the Rhone site which exhibited EROD levels as high as the EROD plateau found in laboratory conditions. A 2-month depu ration period in clean water was necessary for EROD activity in wild gudgeo n to decrease to baseline levels. These results provide better knowledge of the main factors of modulation of the induction in gudgeon as well as on t he influence of the history of exposure to inducers.