Phytosterols or plant sterols (PS) are consumed as natural remedies and margarines by the general population in developed countries to lower elevated serum cholesterol levels. They are also present in high concentrations in pulp mill effluents. The aim of the study was to screen the endocrine and metabolic parameters of the European polecat (Mustela putorius) for the effects of PS. The results showed an increase in the plasma estradiol and TH levels with no effects on the hypophyseal regulatory hormones. The plasma ghrelin levels decreased. PS also affected intermediary metabolism. The liver glycogen content increased as did the kidney glucose-6-phosphatase activity. The liver lipase esterase activity, on the other hand, decreased due to PS. In serum lipids the total cholesterol did not change, but the low-density lipoprotein levels increased and the high-density lipoprotein-cholesterol ratio decreased. PS had widespread previously unreported effects on the physiology of the polecat. The multiple effects indicate the need of a thorough risk assessment of the effects and interactions of PS.
[Show abstract][Hide abstract] ABSTRACT: Phytosterols or plant sterols (PS) enter the ecosystem via pulp mill effluents. They are also consumed by the general population of developed countries in natural remedies and margarines to lower elevated serum cholesterol levels. This study screened the endocrine and enzymatic parameters of the field vole (Microtus agrestis) for the effects of subchronic PS exposure at three doses (0, 5, or 50 mg of PS kg(-1) day(-1)). PS at 5 or 50 mg kg(-1) day(-1) decreased the relative liver weight of the voles. The kidney glycogen phosphorylase activity decreased at 5 or 50 mg kg(-1) day(-1), but the liver glycogen phosphorylase activity increased at 5 mg kg(-1) day(-1). The plasma estradiol and testosterone concentrations of males were higher due to PS supplement at 5 mg kg(-1) day(-1). This can be due to increased sex steroid synthesis from PS precursors. Biotransformation enzyme activities were not affected. PS caused multiple, previously unreported effects that were more pronounced at a low dose. As 5 mg PS kg(-1) day(-1) is the recommended dose for various health products, a thorough risk assessment of the effects and interactions of PS is warranted.
Experimental Biology and Medicine 03/2003; 228(2):188-93. · 2.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Phytosterols (PS) are the analogues of animal cholesterol in various plants. beta-Sitosterol is a PS used in margarines and natural remedies to lower elevated serum cholesterol levels. PS enter the ecosystem via pulp mill effluents. The study investigated the endocrine and metabolic effects of PS on the female raccoon dog (Nyctereutes procyonoides), a canid omnivore. Eight female animals were exposed perorally to 8 mg PS/kg/d for 4 wk with 8 animals in the control group. In the PS-treated females, there was a transitory decrease in the plasma estradiol concentrations with an increase in the plasma follicle-stimulating hormone levels. The plasma triiodothyronine concentrations were higher in the PS group. Serum lipid concentrations decreased in PS-treated and control animals. This probably represents a seasonal adaptation. Most of the cholesterol in raccoon dog serum was high-density lipoprotein cholesterol, unlike that in humans but similar to some other carnivores. Liver and kidney ethoxyresorufin O-deethylase activities were lower in the PS treated females. Data indicate that raccoon dogs may not be a sentinel species for PS effects.
Journal of Toxicology and Environmental Health Part A 09/2003; 66(15):1475-88. DOI:10.1080/15287390306412 · 2.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to obtain basic knowledge of the plasma concentrations and interactions of weight regulatory hormones in juvenile minks (Mustela vison). Ghrelin, leptin, and growth hormone (GH) levels were validated and determined by radioimmunoassay methods from the plasma of 30 female and 30 male minks. The female minks had higher plasma ghrelin and GH levels than the males. The plasma ghrelin concentrations of the females correlated positively with their body masses (BMs). The plasma leptin levels did not differ between sexes, but there was a positive correlation between the plasma leptin concentrations and BMs in the male minks. When the data from the male and female minks were combined, the correlation between the leptin levels and the BMs was still clear, but this was not observed in the females alone. In the male minks, the plasma GH levels correlated positively with the BMs and with the plasma leptin concentrations. However, there was no correlation between the plasma ghrelin and GH or leptin concentrations. The hormone concentrations were quite similar to earlier measurements in other carnivores.
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