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2L - Immunotoxicity - genotoxicity - ED (WEP/125) Dietary phytosterol supplement increases the probability of reproduction and modifies sex steroid concentrations of voles. Nieminen, Petteri1, Kukkonen, Jussi1, Mustonen, Anne-Mari1, Päiväläinen, Pirkko1, 1 Department of Biology, University of Joensuu, Joensuu, Finland ABSTRACT- Phytosterols (PS) are the analogues of animal cholesterol in plants. Key words: root vole, Phytosterols, reproduction, testosterone |
-sitosterol is a PS used in margarines and natural remedies to treat elevated serum cholesterol levels due to its ability to inhibit cholesterol absorption in the intestine. PS enter the natural ecosystem is excess via pulp mill effluents and they seem to be a cause of intersexuality and reproductive disturbance in fish. The study investigated the effects of PS on root vole (Microtus oeconomus) reproduction and endocrinology. The 82 voles were treated with a regular diet or the same diet with PS supplement (5 mg/kg/d; recommended dose of PS in margarines and natural remedies). The voles were allowed to reproduce freely. The parents and the offspring were sampled when the offspring had reached three weeks of age (weaning age). Reproductive parameters, plasma sex steroids and thyroid hormones, leptin and ghrelin were determined using radioimmunoassays validated for the species. Liver and kidney glycogen content, glucose-6-phosphatase, glycogen phosphorylase and lipase esterase activities were measured spectrophotometrically. The percentage of reproduced pairs was higher in the PS group (c2 test, p < 0.001), but in males plasma and testicular testosterone concentrations were lower due to PS treatment (p < 0.05, two-way ANOVA). The results on reproduction and sex steroids were unexpected and no obvious mechanism for these phenomena could be detected. As it is impossible to study the effects of PS on human reproduction and the effects of PS are species-specific; it could be prudent to use several species when assessing the long-term effects of PS.