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Environmental estrogens may be derived from plants (phytoestrogens), pharmaceuticals or synthetic compounds. They exert estrogenic and/or potentially antiestrogenic effects on farm animals, wildlife and humans. Exposure to these compounds results in some abnormalities in the reproductive tract, changes in the estrous cycle, and possibly protection against the development of hormone- dependent cancer. The data obtained from animal studies suggest that the timing of exposure to phytoestrogens is important, and neonatal exposure causes the most pronounced effects.
Granulosa cells were isolated from large (≥8 mm) follicles and incubated for 24 h without or with LH (100 ng/mL), daidzein, genistein or equol in doses of 0.5, 5, 10, and 50 µg/mL each or combination (3:13:39) of these isoflavones at a dose 50 µg/ml. The concentration of oestradiol-17ß in incubation media was measured by RIA. All the isoflavones at used doses decreased significantly basal and LH-stimulated secretion of oestradiol-17ß by granulosa cells in a dose dependent manner. The combination of these isoflavones also inhibited significantly oestradiol-17ß secretion by the cells. These data suggested that decreased secretion of oestradiol-17ß caused by dietary isoflavones could be a reason of silent heat in cows.
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.
Genistein, a major phytoestrogen of soy, is considered a potential drug for prevention and treatment of postmenopausal osteoporosis. The aim of the present study was to compare the effects of genistein, estradiol and raloxifene on the skeletal system in vivo and in vitro. Genistein (5 mg/kg), estradiol (0.1 mg/kg) or raloxifene hydrochloride (5 mg/kg) were administered daily by a stomach tube to mature ovariectomized Wistar rats for 4 weeks. Bone mass, mineral and calcium content, macrometric parameters and mechanical properties were examined. Also the effects of genistein, estradiol and raloxifene (10-9-10-7 M) on the formation of osteoclasts from neonatal mouse bone marrow cells and the activity of osteoblasts isolated from neonatal mouse calvariae were compared. In vivo, estrogen deficiency resulted in the impairment of bone mineralization and bone mechanical properties. Raloxifene but not estradiol or genistein improved bone mineralization. Estradiol fully normalized the bone mechanical properties, whereas genistein augmented the deleterious effect of estrogen-deficiency on bone strength. In vitro, genistein, estradiol and raloxifene inhibited osteoclast formation from mouse bone marrow cells, decreasing the ratio of RANKL mRNA to osteoprotegerin mRNA expression in osteoblasts. Genistein, but not estradiol or raloxifene, decreased the ratio of alkaline phosphatase mRNA to ectonucleotide pyrophosphatase phosphodiesterase 1 mRNA expression in osteoblasts. This difference may explain the lack of genistein effect on bone mineralization observed in ovariectomized rats in the in vivo study. Concluding, our experiments demonstrated profound differences between the activities of genistein, estradiol and raloxifene towards the osseous tissue in experimental conditions.
Introduction and objective. Phytoestrogens are one of nutritional factors exhibiting a chemoprotective action, potentially reducing vasomotor symptoms as well as cancerous lesions. The study was ocused on an association between the consumption of phytoestrogens in the diet, blood serum cholesterol concentration and urinary estrogen metabolites levels. Materials and methods. The study was conducted on 55 women in the perimenopausal period, who were characterized by an increased risk of hormone-dependent cancer. Energy and nutritive value of food rations, and especially the level of phytoestrogen consumption in the diets in the examined population, were analyzed using the Wikt Pro computer programme. Estrogen metabolites (2OHE, 16α-OHE1) were determined from 24‑urine samples by the ELISA method. The EMR index was calculated. Plasma total cholesterol concentrations was measured. Results and conclusions. The population with a higher consumption of phytoestrogens and dietary fibre in the diet, at the simultaneous slight limitation of energy value of the food ration, is characterized by an improved blood serum cholesterol concentration and an appropriate estrogen metabolism towards a significant increase in the estrogen index for the cancer lesions in the mammary glands.
Na podstawie danych piśmiennictwa scharakteryzowano wybrane aspekty żywieniowe i zdrowotne u ludzi związane z naturalnym występowaniem w żywności fitoestrogenów - związków o działaniu estrogennym.
The aims of the study were to compare the in vitro effects of daidzein or 17ß-estradiol (E2) on: 1) progesterone (P4) secretion by luteinized granulosa cells harvested from large porcine follicles, as well as 2) estrogen receptor and ß (ER and ERß) mRNA and protein expression in the cells. In addition, the effect of daidzein on E2 secretion and viability of the granulosa cells was examined. We found that basal and gonadotropin-stimulated P4 secretion were inhibited in granulosa cells cultured in the presence of daidzein either for 24 or 48 hours. In contrast to daidzein, E2 reduced P4 secretion only during 24-hour cell cultures increasing it during longer cultures. Daidzein did not affect E2 secretion by granulosa cells. The expression of ER and ERß mRNA, as well as ERß protein, was up-regulated by daidzein but unaffected by E2. To conclude, the soy estrogen daidzein acts directly on the porcine ovary to decrease progesterone production and to increase expression of ERß mRNA and protein. Daidzein actions in porcine luteinized granulosa cells differ from those of estradiol and it may suggest disadvantageous effects of the phytoestrogen on reproductive processes in females.
Authors performed a review of a current literature related with a structure, physiology and effects of estrogen receptor function. Our article contains information about molecular structure of SHR family (steroid hormone receptors), a way of binding with their ligands. We tried to present step by step a mechanism of receptor reaction with nucleic acids also a mechanism of initiation of transcription. We clearly described a function and action of cofactor proteins in a process of receptor activation. We mentioned about fitoestro- gens influence on estrogen receptor molecules.
Omówiono wybrane substancje szkodliwe oraz toksyczne wytwarzane przez rośliny wyższe oraz bytujące w środowisku wodnym (glony). Zwrócono uwagą na wielokierunkowe działanie na organizm ludzki omawianych związków i ich przemiany.
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