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В работе исследовалось влияние куместрола и эстрола, которые животные употребляли вместе с кормом в течение года, на некоторые параметры липидного и углеводного метаболизма недоразвитых в половом отношении самок крыс. Как куместрол, так и эстрон не имели существенного влияния на уровень обоих липидов, а также холестерола в сыворотке крови, в печени и в мышцах исследуемых животных. Куместрол привел в повышению концентрации триглицеридов в сыворотке крови через час после его употребления. Наблюдалось существенное снижение количества гликогена в печени и мышцах после употребления куместрола. Это может свидетельствовать о тормозящем действии этого фитоэстрогена на синтез гликогена у недоразвитых в половым отношении самок крыс.
Genistein, a plant-derived compound, is a phytoestrogen and has a quite well-documented effect on carbohydrate and lipid metabolism in animals. Data is lacking, however, about the influence of this compound when the level of endogenous oestrogens is high, for example in pregnancy. The aim of the performed experiment was to investigate the effect of dietary genistein (100 mg/kg of feed) on some blood hormone concentrations and metabolic parameters in pregnant rats. Two groups of pregnant Wistar rats were used: the animals in one group were fed a diet without genistein and in the other, a genistein-supplemented diet. Animals from both groups were sacrificed on day 13 or 18 of gestation or on the first day after delivery. Additionally, one group of control non-pregnant rats was fed a diet without genistein and used to compare with pregnant rats. The blood sera, livers and skeletal muscles of animals were collected and stored (-80 °C) until analysis. Genistein caused a substantial decrease of the serum leptin concentration on day 18 of gestation and of leptin and ACTH concentrations on the first day after delivery. The serum insulin, glucagon and corticosterone concentrations remained unaffected by genistein. The tested compound did not influence serum glucose, triglycerides, free fatty acids, cholesterol or liver and muscle glycogen, triglycerides and cholesterol. These results suggest that genistein, despite its well-described oestrogenic potency, can not manifest its action during pregnancy because of high levels of endogenous oestrogens.
Genistein is a phytoestrogen and is found in many plants consumed by humans and animals. This isoflavone was found to exert metabolic effects, especially on lipid and carbohydrate metabolism. The aim of this experiment was to determine whether genistein at a dose of 1 and 5 mg/kg body weight administered intragastrically to male and female adult rats changes insulin, leptin, thyroid hormone, and metabolic parameters. The results suggest that genistein has only a slight influence on metabolism. A substantial reduction of triglyceride stores was observed in the skeletal muscles. This effect was sex-dependent and occurred only in females. Moreover, it was demonstrated that genistein at the higher dose decreased blood insulin and leptin levels.
Phytoestrogens are compounds found in plants with estrogenic activity. Their chemical structure is similar to estradiol. Three main classes of phytoestrogens are: isoflavones, lignans and coumestans. The major bioactive isoflavones are genistein and daidzein. Phytoestrogens are widely present in plants regularly consumed by animals and humans: e.g. oats, barley, wheat, corn, and clover. The most significant sources of isoflavones are soybeans and soy foods. Lignans are present in plant foods: mainly in flaxseed, but also in grains, fruit and vegetables. Phytoestrogens are compounds which exhibit estrogenic activity. This activity was first recognized in sheep and is known as “Clover Disease”. In these animals phytoestrogens cause reproductive disorders or even infertility. The feeding of female rats with a soy rich diet induces an increase in uterine weight. Vaginal modifications have also been observed. Phytoestrogens also exhibit anticarcinogenic activity. Animal studies have demonstrated reduced cancer development with soybean consumption. Genistein and other phytoestrogens have a beneficial role in obesity and diabetes mellitus. These compounds cause slight decreases in insulin, total cholesterol and triglycerides content. Phytoestrogens also increase the amount of cholesterol in high density lipoproteins (HDL) and decrease the amount of VLDL- and LDL-cholesterol, they can reduce risk of cardiovascular diseases. Experiments performed on animals demonstrate that genistein and daidzein clearly inhibit lipogenesis and enhance lipolysis. Phytoestrogens also have a special role in the prevention of osteoporosis.
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