Estrogen Receptor α and β Expressions in Hypothalamus-pituitary-ovary Axis in Rats Exposed Lactationally to Soy Isoflavones and Bisphenol A

Objectives This paper aims to investigate the uterotrophic activities of lactational exposure to combination of soy isoflavones （SIF） and bisphenol A （BPA） and to examine estrogen receptor α （ERα） and estrogen receptor β （ERβ） expressions in hypothalamus-pituitary-ovary axis and uterus.Methods Maternal rats that were breeding about 8 litters were randomly divided into four groups with seven dams in each group.Dams in different treatment groups received corn oil （control）,150 mg/kg BW of SIF,150 mg/kg BW of BPA or combination of 150 mg/kg BW of SIF and 150 mg/kg BW of BPA,respectively,from postnatal day 5 to 11 （PND5-11） by gavage.On PND12 and PND70,10 female litters were killed and hypothalamus,pituitary,ovary and uterus were collected.ERα and ERβ expressions in these organs were detected with Western blotting assay.And vaginal opening time and estrus cycle were examined in animals fed for PND70.Results On PND12,the relative uterine weight of rats treated with ISF or BPA or their combination was significantly higher than that of untreated rats （P〈0.05）.But the relative uterine weight of rats in the co-exposure group was slightly lower than that in the group only exposed to SIF or BPA.On PND 70,however,the relative uterine weight in each treatment group was not statistically different from that in the control group （P〈0.05）.Vaginal opening time and estrus cycle in groups treated with SIF or BPA or their combination were similar to those in the control group （P〈0.05）.Exposure to SIF or BPA or their combination could up-regulate or down-regulate ERα and ERβ expressions in hypothalamus,pituitary,ovary and uterus on PND12 and PND70.These regulation patterns for ERα and ERβ were different in different organs at different time points.Conclusion Lactational exposure to ISF or BPA or their combination could induce uterotrophic responses in neonate rats,which disappeared in later life.But these data fail to suggest a possibility for synergic actions between SIF and BPA.It was also demonstrated that the uterotrophic effects of SIF and BPA exposure might,at least,involve modification of ERα or ERβ expressions in the hypothalamus-pituitary-ovary axis.

Consumption of soybean,soy foods,soy isoflavones and breast cancer incidence:Differences between Chinese women and women in Western countries and possible mechanisms

Breast cancer is one of the most lethal diseases world-wide.However,there is a large difference in breast cancer incidence among Caucasian,Hispanic,African and Asian(e.g.Chinese)women with Caucasian women being the highest and Asian women being the lowest.It has been suggested that the dietary factors may account for approximately 50%of the breast cancer.One of such dietary components which are typical to Asian but not Caucasian diet is soy foods.A number of epidemiological studies have suggested that increasing soy consumption could be related to the decreased risk of occurrence and/or mortality of breast cancer.In this review,we first described briefly different types of soy products and their nutritional functions and consumption.Then,we described briefly soybean isoflavones,i.e.genistein(GEN),daidzein,glycitein,and presented several lines of evidence to demonstrate the possible association of soy flavone food consumption with incidence and prognosis of breast cancer;finally,we summarized several possible molecular mechanisms,including the effects of GEN as an agonist of ER,epigenetic and genome-wide effects,activation of peroxisome proliferator-activated receptors,induction of apoptosis and stimulation of autophagy,involved in the chemo-preventive effects of GEN on breast cancer.©2013 Beijing Academy of Food Sciences.Production and hosting by Elsevier B.V.All rights reserved.

Effect of Soy Isoflavone Crude Extract Supplementation on High Fat Diet-induced Insulin Resistance in Ovariectomized Rats

Female Wister rats aged 8 weeks were randomly divided into sham operation group, ovariectomized （OVX） control group, and 20VX groups fed with soy isoflavone crude extract supplementation. The rats had free access to high fat diet and water for 9 weeks. No significant difference was found in body weight （BW）, total abdominal fat, food intake and food utilization rate between OVX control group and 20VX groups. However, the fasting blood glucose and blood lipid levels were significantly higher in 20VX groups than in OVX control group （P〈0.05）. Intraperitoneal glucose tolerance test （IGTI＂） showed that the area under AUC was smaller in 20VX groups than in OVX control group （P〈0.05）. These findings showed that soy isoflavone crude extract supplementation can improve glucose tolerance and prevent high fat diet-induced insulin resistance in ovariectomized rats.

Soy isoflavone extracts stimulate the growth of nude mouse xenografts bearing estrogen-dependent human breast cancer cells(MCF-7)

We explored the effects of different lifetime exposures to soy isoflavone extracts on the growth of estrogen- dependent human breast cancer cells （MCF-7） implanted into athymic mice of different ovarian statuses. The athymic mice, ovariectomized or not, were implanted with MCF-7 cells. Mice were fed with low, moderate and high doses of soy isoflavone extract, at dietary concentrations of 6.25, 12.5 and 25 g/kg, in different reproductive models, respectively. The expression of ki-67 was detected by immunohistochemistry, pS2 expression in tumors was analyzed by real-time PCR. Estrogen level in the serum was measured by chemiluminescence enzyme im- munoassay. Total genistein and daidzein levels in serum and urine were determined by liquid chromatography- electrospray tandem mass spectrometry （LC-ES/MS/MS）. In Group A, on week 4, nude mice were exposed to different doses of soy iosflavone extracts. In Group B, the experimental diets were given to the nude mice follow- ing ovariectomy and tumor implantation. In both groups, 6.25 and 12.5 g/kg soy isoflavone extracts stimulated the growth of MCF-7 xenografts, increased pS2 expression, proliferation and estrogen level in serum. In both Group B （postmenopausal mouse model） and Group C （premenopausal mouse model）, soy isoflavone extracts at doses of 6.25 and 12.5 g/kg showed stimulatory effects on the growth of MCF-7 tumors. In conclusion, administration of soy isoflavone extracts at doses of 6.25 and 12.5 g/kg during adolescence or later in life stimulated tumor growth in both menopausal and postmenopausal mouse models.

Subchronic Toxicity Study on Soy Isoflavones in Rats

Objective To investigate the subchronic toxicity of soy isoflavones （SIF） in male rats. Method Fifty Sprague-Dawley rats were randomly divided into 5 groups, 10 rats per group. SIF were given to rats in different groups by gavage at dose of 0, 0.2, 0.5, 1.5, and 4.5 g/kg bw, respectively for 13 weeks. Clinical manifestations, body weight, and food consumption were observed weekly. At the end of the study, urinalysis, hematology, clinical chemistry, total testosterone, and follicle-stimulating hormone were tested, and histopathological examinations were performed. Results No mortality, ophthalmic abnormalities or treatment-related clinical signs were identified during the study. As compared with the control group, significantly lower body weights and food consumption were observed in 1.5 and 4.5 g/kg bw groups. In clinical chemistry tests, triglyceride was significantly decreased and high-density lipoprotein cholesterol was significantly increased in all SIF-treated groups. Total testosterone levels were significantly lower in 0.50, 1.50, and 4.5 g/kg bw dose groups than in the control group. Microscopic examination showed that the mammary glands exhibited hyperplasia and excreted latex in rats of the 4.5 g/kg bw group. No changes attributable to treatment of SIF in other parameters were found. Conclusion SIF at high dosages caused significant endocrine disruption in male rats. The no observed adverse effect level （NOAEL） of SIF to male rats in this study is considered to be 0.20 g/kg bw.

Molecular docking studies of human MCT8 protein with soy isoflavones in Allan-Herndon-Dudley syndrome(AHDS)

Monocarboxylate transporter-8 （MCT8） is a specific thyroid hormone transporter, essential for the uptake of thyroid hormone into target tissues. Mutations in the MCT8 gene have been identified as the cause of Allan-Herndon-Dudley syndrome （AHDS）. It has been reported that soy isoflavones influence thyroid hormone system and can interact with thyroid hormone transporter proteins. Therefore, the present study aimed to find out whether soy isoflavones （genistein, daidzein and glycitein） can be used as a natural inhibitor to target MCT8 in AHDS. Docking studies were performed for soy isoflavones in order to evaluate their binding affinity to MCT8 protein using AutoDock4 （version 4.2.6） and AutoDock Vina. After docking, the ligands were ranked according to their binding energy and the best lead compound was selected based on the least binding energy. The docking results indicated that daidzein possesses the lowest binding energy against MCT8. Moreover, it was found that the residues PRO-338, HIS-341, and GLU-348 were involved in hydrogen bond interactions with genistein and daidzein. This study suggests that daidzein is a promising natural inhibitor to target MCT8 in AHDS.

Effect of daily supplementation of soy isoflavones on hot flashes and night sweats in African menopausal women

The aim of this study was to evaluate the effectiveness of a pharmaceutical grade isoflavone supplement (Inoclim?) 40 mg per capsule of soy extract rich in daidzin and genistin) on the number of hot flashes and night sweats in menopausal African women. This open, prospective, multicenter study involved 140 menopausal women with climacteric symptoms (i.e., a minimum of five hot flashes and/or moderate to severe night sweats per day). These patients received a daily 40-mg supplement of soy isoflavone contained in an Inoclim? capsule (Laboratoire Innotech International, France). The dose was increased to two capsules per day when there were more than five hot flashes or when the women could not sleep because of night sweats. The patients were followed up over a 4-month period and data were analyzed using EPI-InfoTM version 3.5.1. The outcome measure was fewer hot flashes and night sweats. The mean daily number of episodes of hot flashes was 5.7 at baseline and 1.8 at week 16, corresponding to a decrease of 68.4% (n = 93 patients at baseline and n = 66 at 16 weeks). The mean number of daily episodes of night sweats was 3.7 at baseline and 0.8 at week 16, corresponding to a decrease of 78.4% (n = 127 patients in the first week and n = 73 at 16 weeks). Over 80% of patients took a single one 40 mg capsule per day. The percentage of patients who adhered to the prescription was more than 95% during the 4-month follow-up period. These results confirm the effectiveness of a pharmaceutical grade isoflavone supplement (40 mg, rich in genistin and daidzin) on vasomotor symptoms in menopausal women.

Effects of soybean isoflavones on reproductive parameters in Chinese mini-pig boars

Background： Soybean isoflavones are structurally similar to mammalian estrogens and therefore may act as estrogen agonists or antagonists. However, it has not been determined if they have any negative effects on reproductive parameters in male livestock. Therefore, the objective of this study was to evaluate the effects of soybean isofiavones on male reproduction using Chinese mini-pig boars as a model. Fifty Xiang boars were randomly divided into five groups and fed diets containing 0, 125, 250, or 500 ppm soybean isoflavones or 0.5 ppm diethylstilbestrol for 60 days. Results： Dietary supplementation with 250 ppm of soy isoflavones markedly increased the testis index （P 〈 0.05）, fructose content （P 〈 0.05）, and o-glycosidase content in testicular tissue （P 〈 0.01）, as well as increased the number of viable germ cells （P 〈 0.01） and the level of Bcl-2 protein （P 〈 0.01）. However, 500 ppm of soybean isoflavones significantly reduced both testis and epididymis indexes （P 〈 0.0S） and lactate dehydrogenase levels （P 〈 0.01）, as well as reduced serum LH and testosterone levels （P 〈 0.05）. High levels of soybean isoflavones also increased malondialdehyde levels （P 〈 0.05）, as well as increased the numbers of early and late apoptotic germ cells （P 〈 0.01） and the level of Bax proteins （P 〈 0.05） in the testis. Conclusions： The results of this study indicate that consumption of soy isoflavones at dietary levels up to 250 ppm did not adversely affect reproductive parameters in Chinese mini-pig boars whereas higher levels of soy isoflavones may adversely affect male reproduction.

Genistein and daidzein reduced chlorpyrifos induced damage in PC12 cell

The present study preliminarily evaluated neurotoxicity injuries induced by chlorpyrifos in PC12 cell,which were used as a model for nervous cell system.In cultured PC12 cell,application of soy isoflavones(genistein,daidzein,monomer and mixture)significantly reduced chlorpyrifos induced toxicity,a widely used pesticide,and resulted in a better cell survival rate.Treatments with isoflavones reduced malondialdehyde content,reactive oxygengeneration and acetylcholine level in medium,and maintained mitochondrial membrane potential integrity.Daidzein enhanced endogenous antioxidant system in PC12 cell with an increasing in superoxide dismutase perunit activity.Genistein reduced acetylcholine content in the medium.Daidzein and genistein showed different effects,and their combined effect were greater than individual.In conclusion,soy isoflavones as an antioxidant and neuroprotectant,enhanced choline metabolism,which effectively mitigated disadvantageous influence of PC12 cell caused by chlorpyrifos.

Potential relevance of diet to breast cancer

Diet is thought to affect the occurrence and progression of breast cancer while the exact relationship between diet and breast cancer remains largely unclear.This review aims to elucidate the association of specific foods with breast cancer and potential underlying mechanisms.For example,sulforaphane is inversely related to the disease while the impacts of soy and meat on breast cancer are disputable.To some extent,soy is a protective factor while red and processed meat is an adverse one.Due to heterogeneity of breast cancer,menopausal and estrogen receptor statuses can influence the diet-cancer relation.In brief,it may be reasonable to recommend breast cancer patients to eat high soy foods and cruciferous vegetables and low red and processed meat.