PARENT SESSION
MA7 Bioassays for Specific Hazards.
9:00 AM to 12:30 PM, Monday, 07 May 2001
Session Chair: Hans Toni Ratte
Room 7

(063) Effects of 4-nonylphenol and 17-ethynylestradiol on reproductive parameters in male and female mosquitofish (Gambusia holbrooki).

Drèze, Vincent¹, Biagianti-Risbourg, Sylvie², Le Gac, Florence¹, Rime, Hélène¹, Monod, Gilles¹, ^{1 2}

ABSTRACT- In a previous study, 4-nonylphenol (4-NP) was shown to disturb sex differentiation and puberty in early life stages of mosquitofish. In the present study, the effects of 1,5-month semi-static exposure to 4-NP (1, 10 and 50 g/L) and 17-ethynylestradiol (EE2, 0.1 g/L) on reproductive parameters were monitored in adult mosquitofish. Exposure to 50 g/L 4-NP resulted in significant effects including lower gonado-somatic index in both sexes, inhibition of ovarian recrudescence in female, and lower sperm count in males exposed from the onset of their first testicular recrudescence. Nevertheless, sperm count was not altered in males exposed when their testicular maturation was achieved. Tremendous histopathological disorders were also observed in the liver of both males and females exposed to 50 g/L 4-NP. No effects were observed after exposure to 1 and 10 g/L 4-NP. This last result may be due to detoxication of 4-NP by biotransformation enzymes in mosquitofish. Induction of hepatic estrogeno-dependant proteins was observed in male mosquitofish both after exposure to 50 g/L 4-NP and to 0.1 g/L EE2. Nevertheless, exposure to EE2 failed to alter the monitored reproductive parameters in both sexes. This study demonstrates susceptibility of reproductive parameters to 4-NP in adult mosquitofish. Results are discussed with respect to possible toxicity of 4-NP on gonadotropic as well as somatotropic axis.

Key words: Gambusia holbrooki, endocrine modulator, 4-nonylphenol, reproduction