Phytoestrogens: endocrine disrupters or replacement for hormone replacement therapy?

Effects of novel flavonoid-enriched yogurt on the diversity of intestinal microbiota in mice

Soy isoflavone glycoside cannot be effectively absorbed by the human intestinal tract, but probiotics with related hydrolases can transform it into aglycone to promote its absorption. In this study, a novel flavonoid-enriched yogurt was developed using an isolated β-glucosidase-producing strain (Lactiplantibacillus plantarum GY). The flavonoid aglycone-enhanced yogurt was fed to ICR mice for 21 days, and its effects were observed. The yogurt can affect the gut microbial diversity of mice, especially increasing the abundance of Parasutterella, the Bacteroidales S24-7 group, and Phascolarctobacterium in the intestinal tract of mice. Meanwhile, the ratio of Bacteroidetes/Firmicutes in the intestinal tract of mice fed with the flavonoid aglycone-enriched yogurt increased. The difference in the content of butyric acid between the L-GY + IS and the control groups was significant (P < 0.05). Therefore, milk fermentation with β-glucosidase-producing strains is a promising approach for developing flavonoid glycoside-enriched yogurt products.

Co-exposure to endocrine disruptors: effect of bisphenol A and soy extract on glucose homeostasis and related metabolic disorders in male mice

OBJECTIVES

Bisphenol A (BPA) is a xenoestrogen, which is commonly used as a monomer of polycarbonate plastics food containers and epoxy resins. Little is known about the interaction effects between xeno- and phyto- estrogens on glucose homeostasis or other metabolic disorders. The aim of this study was to examine effects of individual or combined exposure to low doses of BPA and soy extract on glucose metabolism in mice with the goal to establish its potential mechanisms.

METHODS

Fifty-four male mice were randomly divided into six groups. Mice were treated with soy extract at 60 or 150 mg/kg by daily gavage with or without subcutaneously administration of BPA (100 μg/kg/day) for four weeks at the same time, while the control group received a vehicle. Serum levels of fasting glucose, insulin, adiponectin, testosterone, malondialdehyde (MDA), and total antioxidant capacity (TAC) were measured. Homeostatic model assessment-β cell function (HOMA-β) index was also determined.

RESULTS

BPA exposure induced hyperglycemia and significantly reduced HOMA-β, serum levels of insulin, adiponectin, testosterone, and TAC and noticeably enhanced MDA in BPA group compared to control one. While treatment with soy extract in high dose (150 mg/kg) significantly decreased the levels of fasting blood glucose and MDA and notably improved the serum levels of insulin, HOMA-β, and TAC compared to BPA group.

CONCLUSION

Soy extract may protect against some adverse effects of BPA. These findings represent the first report suggesting a potential effect between soy extract and BPA in low doses, however, further studies are needed to confirm these results.

The effects of estradiol valerate and remifemin on liver lipid metabolism

To investigate the lipid metabolism dysregulation in the liver of ovariectomized (OVX) rats and effects of estradiol valerate (E) and remifemin (ICR) thereon, forty female Sprague-Dawley rats were randomly divided into sham-operated (SHAM), OVX, OVX+E, and OVX+ICR group. After 4 weeks' E or ICR treatment, serum estrogen, cholesterol, and triglyceride levels; lipid droplets in hepatocytes; hepatocyte morphology; and the expression of estrogen receptor α (ERα), liver X receptor (LXR), and sterol regulatory element binding proteins (SREBPs) in the liver of the rats were assessed. OVX rats had significantly decreased serum estrogen levels, which significantly increased after treatment with E but not with ICR. Serum triglyceride levels and the amount of lipid droplets in hepatocytes increased after ovariectomy, and significantly decreased after E treatment. In addition, ICR treatment markedly increased serum triglyceride levels and lipid droplet size. No significant differences in the serum cholesterol levels were observed among the four groups. After ovariectomy, hepatocyte mitochondria became hypertrophic and misformed, which were reversed with E or ICR treatment. ICR-treated rats also showed endoplasmic reticulum disorganization. After ovariectomy, ERα and LXR levels significantly decreased while SREBP expression increased. E treatment increased ERα and LXR levels while ICR treatment only increased LXR expression. E treatment decreased SREBP-1c levels, whereas SREBP-1c levels increased with ICR treatment. Treatment with E significantly reversed the ovariectomy-induced dysregulation of hepatocyte lipid metabolism, which was, however, exacerbated with ICR treatment. The effects of E and ICR on hepatocyte lipid metabolism may involve the regulation of LXR and SREBP-1c.

Plant derived alternatives for hormone replacement therapy (HRT)

Abstract Hormone replacement therapy (HRT) has undisputable positive effects on climacteric complaints, in the bone and on body weight but also several undesired side effects. Therefore, plant-derived alternatives are currently promoted. Phytoestrogens - primarily the isoflavones genistein, daidzein and coumestrol, stemming from soy (Glycine max) or red clover (Trifolium pratense) - were suggested to have the desired but not the undesired effects of estrogens. Most recently published placebo-controlled studies question the beneficial effects. When taken at the time of puberty however, phytoestrogens appear to protect against mammary cancer later in life. Extracts from the rhizome of Cimicifuga racemosa (black cohosh) have no estrogenic effects. In a narrow dose range they have beneficial effects on climacteric complaints, which are due to several compounds with dopaminergic, noradrenergic, serotoninergic and GABAergic actions that act together in the hypothalamus. Ecdysone is produced by several plants, including spinach (Spinacia oleracea) and was very early on shown to increase muscle mass. Later it became apparent that spinach extracts containing ecdysone decreased body fat load, thereby reducing secretion of proinflammatory cytokines by visceral adipocytes and oxidative stress. This had beneficial effects on body weight and serum lipids not only in obese postmenopausal but also in premenopausal women and in men. For the above-described plant extracts, solid placebo-controlled clinical trials are available. For other plant extracts claiming beneficial effects on climacteric complaints or postmenopausal diseases, no solid data are available.

Isoflavone intake inhibits the development of 7,12-dimethylbenz(a)anthracene(DMBA)-induced mammary tumors in normal and ovariectomized rats

To determine the associations between isoflavone (49.72% genistin, 5.32% daidzin, 34.54% glycitin) and breast cancer risk, 150 rats were given 5 mg 7,12-dimethylbenz(a)anthracene and half of them were ovariectomized. Then normal rats and ovariectomized rats were divided into 5 groups: control group, isoflavone high (HI), middle (MI), or low (LI) dose group consuming 100, 500, or 1000 mg isoflavones/kg diet, estrogen group (2.5 mg stilboestrol/kg diet). After 24 weeks, tumor incidences were 73% in control group, 7% in HI, 7% in MI, 27% in LI, and 80% in estrogen group for normal rats; 60% in control group, 13% in HI, 7% in MI, 13% in LI, and 73% in estrogen group for ovariectomized rats. Isoflavone treatment decreased tumor incidence and mean tumor number per rat and increased mean latent period compared with those in control group and estrogen group group significantly (p<0.05). The mRNA and protein expression of estrogen receptor β were significantly higher in isoflavone treatment groups than those in control group group. Moreover, isoflavone treatment significantly decreased 8-hydroxydeoxyguanosine content and increased superoxide dismutase level in normal rats and decreased malondialdehyde concentrations in ovariectomized rats compared with control group. In conclusions, isoflavone intake significantly inhibited the development of premenopausal and postmenopausal mammary tumors.

Biochanin a promotes osteogenic but inhibits adipogenic differentiation: evidence with primary adipose-derived stem cells

Biochanin A has promising effects on bone formation in vivo, although the underlying mechanism remains unclear yet. This study therefore aimed to investigate whether biochanin A regulates osteogenic and adipogenic differentiation using primary adipose-derived stem cells. The effects of biochanin A (at a physiologically relevant concentration of 0.1-1 μM) were assessed in vitro using various approaches, including Oil red O staining, Nile red staining, alizarin red S staining, alkaline phosphatase (ALP) activity, flow cytometry, RT-PCR, and western blotting. The results showed that biochanin A significantly suppressed adipocyte differentiation, as demonstrated by the inhibition of cytoplasmic lipid droplet accumulation, along with the inhibition of peroxisome proliferator-activated receptor gamma (PPAR γ ), lipoprotein lipase (LPL), and leptin and osteopontin (OPN) mRNA expression, in a dose-dependent manner. On the other hand, treatment of cells with 0.3 μM biochanin A increased the mineralization and ALP activity, and stimulated the expression of the osteogenic marker genes ALP and osteocalcin (OCN). Furthermore, biochanin A induced the expression of runt-related transcription factor 2 (Runx2), osteoprotegerin (OPG), and Ras homolog gene family, member A (RhoA) proteins. These observations suggest that biochanin A prevents adipogenesis, enhances osteoblast differentiation in mesenchymal stem cells, and has beneficial regulatory effects in bone formation.

Black Cohosh and Breast Cancer

Background. Many women use black cohosh as a natural treatment for menopausal symptoms. However, controversy exists around safety in breast cancer, because of its purported estrogenic activity. We conducted a systematic review of black cohosh use in women with or at risk of breast cancer. Methods. We searched MEDLINE, Embase, the Cochrane Library, and AMED from inception to July 2012 and October 2012 for human interventional or observational data pertaining to the safety and efficacy of black cohosh in patients with or at risk of breast cancer, including an assessment of the effect of black cohosh on estrogen responsive tissues. Results. Of 450 records, we included 26 articles: 14 randomized controlled trials, 7 uncontrolled trials, and 5 observational studies.The evidence on efficacy for ho t flashes is divided, with some benefits seen when compared with baseline, but not when compared with placebo. Two observational studies found no association between black cohosh and risk of breast cancer, whereas 2 studies reported significant reductions in risk of primary breast cancer among postmenopausal women (adjusted odds ratio = 0.47, 95% confidence interval = 0.27-0.82), and risk of recurrence (adjusted hazard ratio = 0.75, 95% confidence interval = 0.63-0.89). Seventeen trials showed no significant impact on circulating hormone levels or proliferation in estrogen responsive tissues. Conclusions. Current evidence does not support an association between black cohosh and increased risk of breast cancer. There is a lack of evidence supporting the efficacy of black cohosh for reduction of hot flashes in breast cancer patients. Given conflicting but promising results, and apparent safety, further research is warranted.

The preventive effect of biochanin a on bone loss in ovariectomized rats: involvement in regulation of growth and activity of osteoblasts and osteoclasts

Biochanin A (BCA) is a major isoflavone abundant in red clover (Trifolium pretense). The protective effect of BCA on bone loss in an ovariectomized (OVX) animal model has never been clarified. The objective of this study was to investigate the biological effects of BCA on bone loss in OVX rats in vivo and on the development of osteoblasts and osteoclasts in vitro. Ovariectomy resulted in a marked increase in body weight and a decrease in femoral bone mineral density and trabecular bone volume that was prevented by BCA or 17 β -estradiol (E2) treatment. However, an increase in uterine weight was observed in E2-treated OVX rats, but not in response to BCA treatment. Treatment with BCA increased the mRNA expression of osterix, collagen type I, alkaline phosphatase (ALP), and osteocalcin and decreased the mRNA expression of tartrate-resistant acid phosphatase (TRAP) and the receptor activator of nuclear factor- κ B ligand (RANKL)/osteoprotegerin (OPG) ratio in the femur of OVX rats. Treatment with BCA or E2 prevented the OVX-induced increase in urinary deoxypyridinoline (DPD) and serum tumor necrosis factor α (TNF- α ) and interleukin-1 β (IL-1 β ). In vitro, BCA induced preosteoblasts to differentiate into osteoblasts and increased osteoblast mineralization. BCA inhibited preosteoclasts and osteoclast proliferation and decreased osteoclast bone resorption. These findings suggest that BCA treatment can effectively prevent the OVX-induced increase in bone loss and bone turnover possibly by increasing osteoblastic activities and decreasing osteoclastic activities.

Daidzein-estrogen interaction in the rat uterus and its effect on human breast cancer cell growth

Sex hormone replacement therapy provides several advantages in the quality of life for climacteric women. However, estrogen-induced cell proliferation in the uterus and mammary gland increases the risk of cancer development in these organs. The lower incidence of mammary cancer in Asian women as compared with Western women has been attributed to high intake of soy isoflavones, including genistein. We have previously shown that genistein induces an estradiol-like hypertrophy of uterine cells, but does not induce cell proliferation, uterine eosinophilia, or endometrial edema. It also inhibits estradiol-induced mitosis in uterine cells and hormone-induced uterine eosinophilia and endometrial edema. Nevertheless, genistein stimulates growth of human breast cancer cells in culture; therefore, it is not an ideal estrogen for use in hormone replacement therapy (HRD). The present study investigated the effect of another soy isoflavone, daidzein (subcutaneous, 0.066 mg/kg body weight), in the same animal model, and its effect on responses induced by subsequent treatment (1 h later) with estradiol-17β (E(2); subcutaneous, 0.33 mg/kg body weight). In addition, we investigated the effects of daidzein (1 μg/mL) or E(2) on the growth of human breast cancer cells in culture. Results indicate that daidzein stimulates growth of breast cancer cells and potentiates estrogen-induced cell proliferation in the uterus. We suggest caution for the use of daidzein or formulas containing this compound in HRD. Future research strategies should be addressed in the search for new phytoestrogens that selectively inhibit cell proliferation in the uterus and breast.

Methanol extract of dried exudate of Commiphora mukul prevents bone resorption in ovariectomized rats

CONTEXT

Gum guggul, a resinous exudate of the plant Commiphora mukul Engl. (Burseraceae), has been found efficacious in the treatment of bone fractures, arthritis, and hyperlipidemic disorders.

OBJECTIVE

The present study is an effort to explore the anti-bone-resorptive potential of the dried methanol extract of the gummy exudate of C. mukul (MECM) in ovariectomized rat model.

MATERIALS AND METHODS

The animals were randomly divided into five groups of equal size (n = 6). Animals in all the groups were ovariectomized except group 1, which was sham operated. Groups 3, 4 and 5 were treated with Raloxifene, MECM 250 mg/kg and MECM 500 mg/kg, respectively. The 2nd group was fed with vehicle.

ASSESSMENT

biochemical estimations, viz., alkaline phosphatase (ALP), tartarate resistant acid phosphatase (TRAP), serum calcium (Ca); biomechanical evaluations, and histopathological examinations.

RESULTS

The LD(50) of MECM was found to be > 2500 mg/kg orally. A significant elevation was observed in the ALP, TRAP, Ca and cholesterol levels in the 2nd group with a significant reduction in biomechnical strength. Groups 3, 4 and 5, showed a significant reduction in TRAP and ALP levels (p < 0.001). The Ca levels were normalized in the groups 4 and 5, while cholesterol levels dropped in group 5. The bone strength, however, was normalized in all the groups (p < 0.001) along with the histopathology.

DISCUSSION AND CONCLUSION

Findings suggested a significant gain in bone strength and nearly complete restoration of bone microarchitecture along with lowered levels of TRAP indicating the anti-bone resorptive potential of the extract.

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 immunoassay. 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 following 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.

The soybean concentrated extract proliferates the vagina of adult rats

OBJECTIVE

The aim of this study was to evaluate changes induced on the vagina of ovariectomized rats after treatment with soybean concentrated extract or conjugated equine estrogens and the association of both drugs.

METHODS

We conducted an experimental study with 50 ovariectomized rats that were randomly divided into five equal groups of 10 animals: GI received vehicle, GII received soybean concentrated extract 46 mg/kg per day, GIII received soybean concentrated extract 120 mg/kg per day, GIV received conjugated equine estrogens 50 μg/kg per day, and GV received conjugated equine estrogens 50 μg/kg and soybean concentrated extract 46 mg/kg per day. The substances were administered by gavage during 21 consecutive days. After that, the animals were killed under anesthesia and the vagina was removed for histological and immunohistochemical analysis. Data were initially submitted to analysis of variance. Whenever a significant difference was detected, the study was complemented with the Tukey-Kramer test for multiple comparisons.

RESULTS

GII did not show any differences on the vaginal epithelium or collagen compared with GI. GIII presented an increase in vaginal epithelium and collagen amount. GIV had the highest amount of collagen and the signals of vaginal proliferation. GV did not show any additional effect compared with GIV.

CONCLUSIONS

Our data suggest that a high dose of isoflavone-rich soy extract may have positive effects on the vaginal structures of ovariectomized rats, but this action is less than that of estrogen treatment on vaginal thickness. In addition, soy extract may not block the estrogen effect on vaginal tissue.

Effect of exercise and Cimicifuga racemosa (CR BNO 1055) on bone mineral density, 10-year coronary heart disease risk, and menopausal complaints: the randomized controlled Training and Cimicifuga racemosa Erlangen (TRACE) study

OBJECTIVE

The aim of this study was to determine the effect of periodized exercise training with and without Cimicifuga racemosa (CR) on bone mineral density (BMD) and 10-year coronary heart disease (CHD) risk in early postmenopausal women.

METHODS

A total of 128 women were randomly assigned to three subgroups: exercise (EG, n = 43), exercise and CR supplementation (EGCR, n = 43), and wellness control (control group [CG], n = 42). Both exercise groups performed a periodized exercise program with high-intensity-resistance/high-impact exercise dedicated to bone parameters interspersed by blocks of 10 weeks of training focusing on CHD parameters. In addition to the exercise program, the EGCR was supplemented with 40 mg/day of CR according to the specification of the manufacturer. A low-intensity exercise program of 60 minutes per week for a period of 10 weeks interspersed with 10-week blocks without exercise was performed in the CG. Primary endpoints were BMD and 10-year CHD risk proposed by Wilson. Secondary endpoints were body composition and menopausal symptoms.

RESULTS

BMD at the lumbar spine was maintained in both exercise groups (EG, -0.1% +/- 2.2%, P = 0.74; EGCR, -0.4% +/- 2.4%, P = 0.40) and significantly decreased (P < 0.001) in the CG (2.0% +/- 2.0%). Both exercise groups significantly differed from the CG (P = 0.001 and 0.005 for the EG and EGCR, respectively); however, no differences between the exercise groups with and without CR was determined. Although slight increases in femoral neck BMD were determined in both exercise groups (EG, 0.5% +/- 3.0%, P = 0.36; EGCR, 0.4% +/- 3.1%, P = 0.52), a reduction was assessed in the CG (-0.6% +/- 2.7%, P = 0.29). No significant differences were determined between the groups. The 10-year CHD risk significantly increased in the EGCR (12.9% +/- 25.1%, P = 0.018) and in the CG (16.5% +/- 27.8%, P = 0.007). The EG did not show corresponding changes (-2.7% +/- 21.9%, P = 0.60). However, no significant between-group differences were observed.

CONCLUSIONS

In conclusion our exercise program favorably affected bone, menopausal symptoms, lean body mass, and, to a smaller extent, 10-year CHD risk in early postmenopausal women. Adjuvant supplementation of CR did not enhance these positive effects.

Rapid effects of phytoestrogens on human colonic smooth muscle are mediated by oestrogen receptor beta

Epidemiological studies have correlated consumption of dietary phytoestrogens with beneficial effects on colon, breast and prostate cancers. Genomic and non-genomic mechanisms are responsible for anti-carcinogenic effects but, until now, the effect on human colon was assumed to be passive and remote. No direct effect on human colonic smooth muscle has previously been described. Institutional research board approval was granted. Histologically normal colon was obtained from the proximal resection margin of colorectal carcinoma specimens. Circular smooth muscle strips were microdissected and suspended under 1g of tension in organ baths containing oxygenated Krebs solution at 37 degrees C. After an equilibration period, tissues were exposed to diarylpropionitrile (DPN) (ER beta agonist) and 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT) (ER alpha agonist) or to the synthetic phytoestrogen compounds genistein (n=8), daidzein (n=8), fisetin (n=8) and quercetin (n=8) in the presence or absence of fulvestrant (oestrogen receptor antagonist). Mechanism of action was investigated by inhibition of downstream pathways. The cholinergic agonist carbachol was used to induce contractile activity. Tension was recorded isometrically. Phytoestrogens inhibit carbachol-induced colonic contractility. In keeping with a non-genomic, rapid onset direct action, the effect was within minutes, reversible and similar to previously described actions of 17 beta oestradiol. No effect was seen in the presence of fulvestrant indicating receptor modulation. While the DPN exerted inhibitory effects, PPT did not. The effect appears to be reliant on a p38/mitogen activated protein kinase mediated induction of nitric oxide production in colonic smooth muscle. The present data set provides the first description of a direct effect of genistein, daidzein, fisetin and quercetin on human colonic smooth muscle. The presence of ER in colonic smooth muscle has been functionally proven and the beta isoform appears to play a predominant role in exerting non-genomic effects.

Osteoprotective effect of extract from Achyranthes bidentata in ovariectomized rats

AIM OF THE STUDY

A Chinese herbal drug, root of Achyranthes bidentata showed a potent inhibitory activity on bone resorption induced by parathyroid hormone (PTH) in a bone organ culture using neonatal mouse parietal bones. The present study is to clarify the fractions responsible for the activity and further explore the osteoprotective effect of the fraction in vivo.

MATERIALS AND METHODS

The hexane, ethyl acetate (EtOAc), n-butanol (n-BuOH) and water soluble fractions of methanol extract of the root of Achyranthes bidentata were prepared and screened for their anti-bone resorption activity using the bone organ culture system. The n-BuOH soluble fraction was further administered orally at doses of 25, 50 and 100mg/(kgday) to ovariectomized (OVX) rats. The analyses of the rat body weight, serum estradiol (E2), total cholesterol and triglyceride levels, uteri weight and measurement of bone mineral density (BMD) were conducted.

RESULTS

The EtOAc and n-BuOH fractions showed the most potent inhibitory activity on PTH-induced bone resorption. Further research using OVX rat model revealed that the n-BuOH fraction significantly prevented BMD loss due to OVX operation. While, the uteri weight and serum estradiol (E2), total cholesterol and triglyceride levels displayed no differences compared with those of control group (OVX rats), suggesting the n-BuOH fraction should have no estrogen-like side effects.

CONCLUSIONS

The results reveal that the n-BuOH soluble fraction of the root of Achyranthes bidentata is effective at preventing bone loss in OVX rats and has a great potential as an alternative tool for the treatment of osteoporosis.