PARENT SESSION

2L - Immunotoxicity - genotoxicity - ED
Poster Hall
8:30 AM - Wednesday, 30 April 2003
Chair: Hansen, P.D.¹, ¹

(WEP/98) Bioaccumulation of the phytoestrogen ¹⁴C--sitosterol in presence of cholesterol in the freshwater snail Lymnaea stagnalisL.

Czech, Petra ¹, Dietrich, Daniel², ¹ RCC Ltd, Itingen, Switzerland, Switzerland² University of Konstanz, Konstanz, Germany, Germany

ABSTRACT- Chemical analysis of sewage treatment plant effluents (STPE) and surface waters in southern Germany revealed concentrations ranging between 20-400 ng/L levels for the phytoestrogen -sitosterol (Koerner, W., 2000). In former experiments the chronic exposure (from 8 up to 12 weeks) of Lymnaea stagnalis to 100 ng/L of the phytoestrogen in the test water generated distinct degenerative changes in the tissue of the albumen gland, an accessory sexual gland (Czech, P. et al., 2000). Experiments were performed with 14C labelled -sitosterol (111 ng/L) over 12 weeks to investigate the fate of this compound in Lymnaea stagnalis. Furthermore, snails were exposed to 14C--sitosterol (111 ng/L) in presence of cholesterol (100 ng/L), the principal precursor for steroidal hormones. The presence of cholesterol modulated the availability of the phytoestrogen in the test water, i.e. the quantity of available (dissolved) 14C--sitosterol in the test water was reduced, most likely due to precipitation of 14C--sitosterol. However, despite the lower availability of 14C--sitosterol in the co-exposure experiment with cholesterol, the absolute amounts of 14C--sitosterol found in different organs of the snails were comparable to those found in the experiment without cholesterol addition. This suggests that 14C--sitosterol was either equally available in both treatments (snails were rasping the adsorbed and precipitated 14C--sitosterol from surfaces) or that 14C--sitosterol is actively taken up by the snail micelles in a rate and concentration limited manner independent of the presence of cholesterol. No significant histopathological changes were found in treated snails compared to the control snails. However, one snail treated with 14C--sitosterol showed distinctive cellular degeneration and granulomas in parts of the prostate tissue.

Key words: phytoestrogen, Lymnaea , 14-C--sitosterol, cholesterol