PARENT SESSION
1D Bioassays for specific hazards (estrogenic effects, genotoxicity, neurotoxicity, ...)
9:00 AM to 7:00 PM, Tuesday, 08 May 2001

(T/EH044) Bioaccumulation of ¹⁴C Cholesterol in presence of the phytoestrogen -Sitosterol in the freshwater snail Lymnaea stagnalis .

Czech, Petra ¹, Van Dijk, André¹, Dietrich, Daniel², ^{1 2}

ABSTRACT- Recent chemical analysis of sewage treatment plant effluents (STPE) and surface waters in southern Germany revealed concentrations ranging between ng - g/L levels for the phytoestrogen -sitosterol. 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. From clinical and pharmacological experiments it is known that -sitosterol acts as an inhibitor of cholesterol absorption in human small bowels and in the rat. The aims of our study were, to investigate whether the specific effects in the albumen gland of the snail can be explained by bioaccumulation of the phytoestrogen -sitosterol. In our experiments snails were initially exposed to ¹⁴C cholesterol at a concentration of 200 ng/L to determine the accumulation of this steroid in the albumen gland of Lymnaea stagnalis. Then snails were exposed to ¹⁴C cholesterol in the presence of -sitosterol to demonstrate the hypothesised competitive displacement of ¹⁴C cholesterol through -sitosterol, which is assumed to have a higher affinity for snail's micelles. Preliminary results show that the phytoestrogen is able to modulate the ¹⁴C cholesterol kinetics in the test-water (in absence or presence of the snails) in that the circulating level of the ¹⁴C cholesterol is lowered in the presence of -sitosterol.

Key words: ¹⁴C cholesterol, -sitosterol, Lymnaea stagnalis , bioaccumulation