Characterization of the pharmacologic profile of a standardized soy extract in the ovariectomized rat model of menopause: effects on bone, uterus, and lipid profile

A Mixture of Cervus elaphus sibiricus and Glycine max (L.) Merrill Inhibits Ovariectomy-Induced Bone Loss Via Regulation of Osteogenic Molecules in a Mouse Model

Osteoporosis is a metabolic skeletal disease characterized by lowered bone mineral density and quality, which lead to an increased risk of fracture. The aim of this study was to evaluate the anti-osteoporosis effects of a mixture (called BPX) of Cervus elaphus sibiricus and Glycine max (L.) Merrill and its underlying mechanisms using an ovariectomized (OVX) mouse model. BALB/c female mice (7 weeks old) were ovariectomized. From 12 weeks of ovariectomy, mice were administered BPX (600 mg/kg) mixed in a chow diet for 20 weeks. Changes in bone mineral density (BMD) and bone volume (BV), histological findings, osteogenic markers in serum, and bone formation-related molecules were analyzed. Ovariectomy notably decreased the BMD and BV scores, while these were significantly attenuated by BPX treatment in the whole body, femur, and tibia. These anti-osteoporosis effects of BPX were supported by the histological findings for bone microstructure from H&E staining, increased activity of alkaline phosphatase (ALP), but a lowered activity of tartrate-resistant acid phosphatase (TRAP) in the femur, along with other parameters in the serum, including TRAP, calcium (Ca), osteocalcin (OC), and ALP. These pharmacological actions of BPX were explained by the regulation of key molecules in the bone morphogenetic protein (BMP) and mitogen-activated protein kinase (MAPK) pathways. The present results provide experimental evidence for the clinical relevance and pharmaceutical potential of BPX as a candidate for anti-osteoporosis treatment, especially under postmenopausal conditions.

The potential anti-osteoporotic effect of exercise-induced increased preptin level in ovariectomized rats

Osteoporosis increases bone fragility and fractures. Preptin hormone is regulated by moderate exercise training and increases bone formation. Therefore, this study was conducted to see how estradiol administration and moderate exercise training affected osteoporotic changes in ovariectomized (OVX) rats. To achieve this aim, 36 healthy adult female Wistar albino rats were randomized into Sham, OVX, ovariectomized estradiol-treated (OVX + E) (OVX + E rats were treated using subcutaneous estradiol benzoate 2.5 μg/kg body weight/day), ovariectomized practicing moderate exercise training, ovariectomized estradiol-treated and practiced a moderate exercise training, and ovariectomized alendronate-treated (OVX + Alen) (OVX + Alen rats were treated orally with alendronate 3 mg/kg body weight/week) groups. Alendronate was used as a standard anti-osteoporotic drug. Moderate exercise training, including therapy with estradiol and alendronate for OVX rats began on the fourth week and lasted for six weeks. Results showed that OVX rats had estrogen and preptin deficiency in serum. These deficiencies were associated with a significant increase in bone resorption biomarkers (urinary deoxypyridinoline and hydroxyproline), and bone formation biomarkers (serum osteocalcin and bone-specific alkaline phosphatase). Also, serum pro-inflammatory cytokines (tumor necrosis factor alpha and interleukin-6) were increased, while bone osteopontin (OPN) expression was decreased. Subsequently, the osteoporotic alterations were verified based on histopathological changes. From the results, estradiol therapy and moderate exercise training significantly improved these findings to the same extent as that of the standard alendronate treatment. Therefore, through their anti-inflammatory properties, increasing bone OPN expression, and regulating serum preptin; estradiol therapy and moderate exercise training can reduce osteoporotic alterations in OVX rats. Thus, combined estradiol therapy and moderate exercise training could be a promising potential therapeutic protocol to reduce postmenopausal osteoporosis. Also, targeting serum preptin and bone osteopontin regulation could have a critical role in the treatment of postmenopausal osteoporosis.

Endocrine disruptors of sex hormone activities

Sex hormones, such as androgens, estrogens and progestins are naturally occurring compounds that tightly regulate endocrine systems in a variety of living organisms. Uncontrolled environmental exposure to these hormones or their biological and synthetic mimetics has been widely documented. Furthermore, water contaminants penetrate soil to affect flora, fauna and ultimately humans. Because endocrine systems evolved to respond to very small changes in hormone levels, the low levels found in the environment cannot be ignored. The combined actions of sex hormones with glucocorticoids and other nuclear receptors disruptors creates additional level of complexity including the newly described "dynamic assisted loading" mechanism. We reviewed the extensive literature pertaining to world-wide detection of these disruptors and created a detailed Table on the development and current status of methods used for their analysis.

Soy protein improves tibial whole-bone and tissue-level biomechanical properties in ovariectomized and ovary-intact, low-fit female rats

BACKGROUND

Osteoporosis and related fractures, decreased physical activity, and metabolic dysfunction are serious health concerns for postmenopausal women. Soy protein might counter the negative effects of menopause on bone and metabolic health due to the additive or synergistic effects of its bioactive components.

OBJECTIVE

To evaluate the effects of ovariectomy (OVX) and a soy-protein diet (SOY) on bone outcomes in female, low-capacity running (LCR) rats selectively bred for low aerobic fitness as a model of menopause.

METHODS

At 27 weeks of age, LCR rats (N = 40) underwent OVX or sham (SHAM) surgery and were randomized to one of two isocaloric and isonitrogenous plant-protein-based dietary treatments: 1) soy-protein (SOY; soybean meal); or, 2) control (CON, corn-gluten meal), resulting in four treatment groups. During the 30-week dietary intervention, animals were provided ad libitum access to food and water; body weight and food intake were measured weekly. At completion of the 30-week intervention, body composition was measured using EchoMRI; animals were fasted overnight, euthanized, and blood and hindlimbs collected. Plasma markers of bone formation (osteocalcin, OC; N-terminal propeptide of type I procollagen, P1NP) and resorption (tartrate-resistant acid phosphatase, TRAP5b; C-terminal telopeptide of type I collagen, CTx) were measured using ELISA. Tibial trabecular microarchitecture and cortical geometry were evaluated using μCT; and torsional loading to failure was used to assess cortical biomechanical properties. Advanced glycation end-product (AGE) content of the femur was measured using a fluorimetric assay, and was expressed relative to collagen content measured by a colorimetric OH-proline assay. Two-factor ANOVA or ANOVCA was used to test for significant main and interactive effects of ovarian status (OV STAT: OVX vs. SHAM) and DIET (SOY vs. CON); final body weight was included as a covariate for body-weight-dependent cortical geometry and biomechanical properties.

RESULTS

OVX had significantly greater CTx than SHAM; SOY did not affect bone turnover markers. OVX adversely affected trabecular microarchitecture as evidenced by reduced BV/TV, trabecular thickness (Tb.Th), trabecular number (Tb.N), and connectivity density (Conn.D), and by increased trabecular separation (Tb.Sp) and structural model index (SMI). SOY increased BV/TV only in ovary-intact animals. There was no effect of OVX or SOY on tibial cortical geometry. In SHAM and OVX rats, SOY significantly improved whole-bone strength and stiffness; SOY also increased tissue-level stiffness and tended to increase tissue-level strength (p = 0.067). There was no effect of OVX or SOY on AGE content.

CONCLUSION

Soy protein improved cortical bone biomechanical properties in female low-fit rats, regardless of ovarian hormone status.

St. John's Wort Regulates Proliferation and Apoptosis in MCF-7 Human Breast Cancer Cells by Inhibiting AMPK/mTOR and Activating the Mitochondrial Pathway

St. John’s Wort (SJW) has been used as an estrogen agonist in the systems affected by menopause. Also, hypericin, a bioactive compound of SJW, has been used as a photosensitizer in photodynamic therapy. In the present study, we investigate the anti-proliferative and pro-apoptotic effects of SJW to demonstrate the chemo-preventive effect in human breast cancer cells. MCF-7 cells were cultured with DMSO or various concentrations of SJW ethanol extract (SJWE). Cell viability, proliferation, apoptosis, the expression of proteins involved in cell growth and apoptosis, and caspase-3/7 activity were examined. SJWE dose-dependently suppressed cell growth and induced apoptosis of MCF-7 cells. Mechanistically, SJWE enhanced the phosphorylation of AMP-activated protein kinase (AMPK) and decreased the expression of p-mammalian target of rapamycin (p-mTOR) and p-eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1). Also, SJWE inhibited the phosphorylation of protein kinase B (Akt) and showed increases in the expression of pro-apoptotic proteins Bax and Bad with decreases in the expression of anti-apoptotic proteins including B-cell lymphoma 2 (Bcl-2), B-cell lymphoma-extra large (Bcl-xL), and p-Bcl-2-associated death promoter (p-Bad). SJWE at 50 μg/mL showed markedly enhanced caspase-7 activation. Taken together, our results provide evidence that SJWE shows anti-proliferative and pro-apoptotic effects via inhibition of AMPK/mTOR and activation of a mitochondrial pathway. Therefore, SJWE can be used as a chemo-preventive agent without photo-activation.

Effects of Hydroalcoholic Extract of Soy on Learning, Memory and Synaptic Plasticity Deficits Induced by Seizure in Ovariectomized Rats

Introduction:

Previous studies have shown that seizure can induce cognitive impairment. On the other hand, soy phytoestrogens, which are mainly found in soybean (Glycine max (L.) Merr.), have beneficial effects on the nervous system. However, little is known about their probable effects on seizure. The present study aimed to examine the probable effects of soy extract, containing the phytoestrogen genistein on seizure-induced cognitive and synaptic plasticity impairment in Ovariectomized (OVX) rats.

Methods:

Rats were ovariectomized, implanted with guide cannula and then divided into 5 groups (n=7–8 in each group): PBS, KA, Saline-KA, Higher Dose Soy (HDS-KA), and Lower Dose Soy (LDS-KA) groups. Animals of the HDS-KA and LDS-KA groups received intraperitoneal administration of soy extract (20 and 2 mg/kg, respectively) and the Saline-KA group received normal saline once a day for 4 days. Sixty minutes after the last injection, Kainic Acid (KA) or PBS was injected into the left lateral ventricle via pre-implanted guide cannula to induce generalized seizures. The Morris water maze task and in vivo field potential recordings were conducted 7 days later.

Results:

Soy extract at both doses significantly improved learning impairment and at the higher dose (20 mg/kg) significantly prevented seizure-induced spatial memory impairment and deficit of long-term potentiation in the hippocampus.

Conclusion:

The soy extract containing the phytoestrogen genistein may have beneficial effects on memory deficit induced by seizure in OVX rats and this effect is accompanied by a beneficial effect on synaptic plasticity.

Transforming growth factor-β3 promotes facial nerve injury repair in rabbits

The present study investigated the effects of transforming growth factor (TGF)-β3 on the regeneration of facial nerves in rabbits. A total of 20 adult rabbits were randomly divided into three equal groups: Normal control (n=10), surgical control (n=10) and TGF-β3 treatment (n=10). The total number and diameter of the regenerated nerve fibers was significantly increased in the TGF-β3 treatment group, as compared with in the surgical control group (P<0.01). Furthermore, in the TGF-β3 treatment group, the epineurial repair of the facial nerves was intact and the nerve fibers, which were arranged in neat rows, were morphologically intact with visible myelin swelling. However, in the surgical control group, the epineurial repair was incomplete, as demonstrated by: Atrophic nerve fibers, partially disappeared axons and myelin of uneven thickness with fuzzy borders. Electron microscopy demonstrated that the regenerated fibers in the TGF-β3 treatment group were predominantly myelinated, with clear-layered myelin sheath structures and axoplasms rich in organelles. Although typical layered myelin sheath structures were observed in the surgical control group, the myelin sheaths of the myelinated nerve fibers were poorly developed and few organelles were detected in the axoplasms. Neuro-electrophysiological examination demonstrated that, as compared with the surgical control group, the latency period of the action potentials in the TGF-β3 treatment group were shorter, whereas the stimulus amplitudes of the action potentials were significantly increased (P<0.01). The results of the present study suggest that TGF-β3 may improve the regeneration of facial nerves following trauma or injury.

Soy Isoflavones and Osteoporotic Bone Loss: A Review with an Emphasis on Modulation of Bone Remodeling

Osteoporosis is an age-related disorder that affects both women and men, although estrogen deficiency induced by menopause accelerates bone loss in older women. As the demographic shifts to a more aged population, a growing number of men and women will be afflicted with osteoporosis. Since the current drug therapies available have multiple side effects, including increased risk of developing certain types of cancer or complications, a search for potential nonpharmacologic alternative therapies for osteoporosis is of prime interest. Soy isoflavones (SI) have demonstrated potential bone-specific effects in a number of studies. This article provides a systematic review of studies on osteoporotic bone loss in relation to SI intake from diet or supplements to comprehensively explain how SI affect the modulation of bone remodeling. Evidence from epidemiologic studies supports that dietary SI attenuate menopause-induced osteoporotic bone loss by decreasing bone resorption and stimulating bone formation. Other studies have also illustrated that bone site-specific trophic and synergistic effects combined with exercise intervention might contribute to improve the bioavailability of SI or strengthen the bone-specific effects. To date, however, the effects of dietary SI on osteoporotic bone loss remain inconclusive, and study results vary from study to study. The current review will discuss the potential factors that result in the conflicting outcomes of these studies, including dosages, intervention materials, study duration, race, and genetic differences. Further well-designed studies are needed to fully understand the underlying mechanism and evaluate the effects of SI on osteoporosis in humans.

St. John's Wort (Hypericum perforatum) stimulates human osteoblastic MG-63 cell proliferation and attenuates trabecular bone loss induced by ovariectomy

BACKGROUND/OBJECFTIVES

The effect of St. John's Wort extract (SJW) on MG-63 cell proliferation and trabecular bone loss induced by ovariectomy was examined.

MATERIALS/METHODS

Proliferation, expression of estrogen receptor (ER) α and ER β, and gene expressions of osteoprotegerin (OPG), osteocalcin (OC) and alkaline phosphatase (ALP) were examined in MG-63 cells treated with or without SJW. Ovariectomized rats were treated with SJW at the dose of 100 or 200 mg/kg/day, β-estradiol-3-benzoate (E2), or vehicle only (OVX-C), and sham operated rats were treated with vehicle only (Sham-C). Serum ALP and C-telopeptide (CTX), and femoral trabecular bone loss were examined.

RESULTS

SJW increased MG-63 cell proliferation and expression of ER α and ER β, and positive effect was shown on gene expressions of ALP, OC and OPG. SJW also showed estrogen like effect on bone associated with slowing down in trabecular bone loss. Histopathology by H&E showed rats treated with SJW displayed denser structure in metaphyseal region of distal femur compared with rats in OVX-C. SJW was shown to reduce serum CTX in OVX rats.

CONCLUSION

The present study provides new insight in preventing estrogen deficiency induced bone loss of SJW and possibility for its application in bone health supplement.

Calorie restriction aggravated cortical and trabecular bone architecture in ovariectomy-induced estrogen-deficient rats

We hypothesized that calorie restriction (CR) and estrogen deficiency (ovariectomy [OVX]) would aggravate bone biomarkers and structural parameters in rats. Seven-week-old female Sprague-Dawley rats were randomized to sham-operated groups and fed either an ad libitum diet (SHAM-AL) or a CR diet (SHAM-CR); ovariectomy-operated groups were fed an ad libitum diet (OVX-AL) or a CR diet (OVX-CR). For 8 weeks, the OVX-AL and SHAM-AL groups were fed the same diet, whereas CR groups were fed a diet containing 50% fewer calories. Bone-related biomarkers and structural parameters (OC; deoxypyridinoline [DPD]; N-terminal telopeptide, NTx; architecture and mineralization; and microcomputed tomography images) were analyzed at the end of the experiment. The serum OC levels of calorie-restricted groups (SHAM-CR and OVX-CR) were significantly lower than those of the AL groups (SHAM-AL and OVX-AL) (P < .05). Urinary DPD levels of calorie-restricted and ovariectomized groups were higher than those of their counterparts (P < .05), whereas urinary NTx levels of calorie-restricted groups were higher than those of AL groups (P < .05). In regard to trabecular bone, the calorie-restricted and ovariectomized groups had lower values of bone volume to total volume, trabecular number, and bone mineral density, but higher values of trabecular separation than those of their counterparts (P < .05). Regarding cortical bone, the calorie-restricted groups had reduced values of bone volume, mean polar moment of inertia, and cortical thickness compared to the AL groups (P < .05). In conclusion, severe CR with or without OVX during the growth period in rats is equally detrimental to bone; CR has detrimental effects on trabecular and cortical bone; and estrogen deficiency only had an effect on trabecular bone.

Effect of St. John's Wort (Hypericum perforatum) on obesity, lipid metabolism and uterine epithelial proliferation in ovariectomized rats

BACKGROUND/OBJECTIVES

This study was conducted to assess the potential of St. John's Wort (Hypericum perforatum) to prevent obesity and abnormalities in lipid metabolism induced by ovariectomy in a rat model without stimulatory activity on uterus.

MATERIALS/METHODS

Ovariectomized (OVX) rats were treated for 6 weeks with 70% ethanol extracts of Hypericum perforatum [HPEs: whole plant (WHPE) and flower and leaves (FLHPE)], β-estradiol-3-benzoate at a dose of 50 µg/kg/day (E2) or vehicle (distilled water).

RESULTS

As expected, OVX increased body weight gain and adiposity and showed higher food efficacy ratio. OVX also increased the serum cholesterol as well as insulin resistance, while reducing uterus weight and uterine epithelial proliferation rate. HPEs (WHPE and FLHPE) showed estrogen-like effect on body weight gain, adipose tissue weight and food efficacy ratio in OVX rats. HPEs prevented hypercholesterolemia induced by OVX more effectively than E2. E2 increased uterus weight and epithelial proliferation rate in OVX rats, while HPEs maintained them at the level of the sham-operated animals.

CONCLUSIONS

Our finding demonstrates that HPEs can be considered as an effective agent to prevent OVX-induced obesity without stimulatory activity on uterus.

Genistein-induced fluid accumulation in ovariectomised rats' uteri is associated with increased cystic fibrosis transmembrane regulator expression

OBJECTIVE

High genistein doses have been reported to induce fluid accumulation in the uteri of ovariectomised rats, although the mechanism underlying this effect remains unknown. Because genistein binds to the oestrogen receptor and the cystic fibrosis transmembrane regulator mediates uterine fluid secretion, we hypothesised that this genistein effect involves both the oestrogen receptor and cystic fibrosis transmembrane regulator.

METHODS

Ovariectomised adult female Sprague-Dawley rats were treated with 25, 50, or 100 mg/kg/day genistein for three consecutive days with and without the ER antagonist ICI 182780. One day after the final drug injection, the animals were humanely sacrificed, and the uteri were removed for histology and cystic fibrosis transmembrane regulator mRNA and protein expression analysis using real-time polymerase chain reaction and Western blotting, respectively. The cystic fibrosis transmembrane regulator protein distribution was analysed visually by immunohistochemistry.

RESULTS

The histological analysis revealed an increase in the circumference of the uterine lumen with increasing doses of genistein, which was suggestive of fluid accumulation. Moreover, genistein stimulated a dose-dependent increase in the expression of cystic fibrosis transmembrane regulator protein and mRNA, and high-intensity cystic fibrosis transmembrane regulator immunostaining was observed at the apical membrane of the luminal epithelium following 50 and 100 mg/kg/day genistein treatment. The genistein-induced increase in uterine luminal circumference and cystic fibrosis transmembrane regulator expression was antagonised by treatment with ICI 182780.

CONCLUSION

Genistein-induced luminal fluid accumulation in ovariectomised rats' uteri involves the oestrogen receptor and up-regulation of cystic fibrosis transmembrane regulator expression, and these findings reveal the mechanism underlying the effect of this compound on changes in fluid volume in the uterus after menopause.

Genistein administered as a once-daily oral supplement had no beneficial effect on the tibia in rat models for postmenopausal bone loss

OBJECTIVE

Estrogen deficiency after menopause results in rapid bone loss, predisposing women to osteoporotic fractures. Genistein, a phytoestrogen present in high concentrations in soy, is an ingredient in dietary supplements aggressively marketed for bone health. However, in a recent long-duration clinical trial in postmenopausal women, the efficacy of soy extracts in reducing bone loss was disappointing. To better understand the failure of soy extracts to consistently induce a robust skeletal response in women, we investigated the long-term (5 mo) efficacy of genistein, administered as a daily oral supplement, (1) in preventing cancellous bone loss in skeletally mature virgin Long-Evans rats ovariectomized at 7 months of age and (2) in improving cancellous bone mass and architecture in aged retired-breeder rats ovariectomized at 16 or 22 months of age.

METHODS

Rats within each age group were randomly assigned into one of three treatment groups (n = 7-12 rats/group): (1) vehicle control, (2) genistein 485 μg/day, or (3) genistein 970 μg/day, resulting in mean (SE) serum genistein levels of 0.18 (0.10), 0.76 (0.15), and 1.48 (0.31) μM, respectively. Total tibia bone mass and density were evaluated using dual-energy x-ray absorptiometry, whereas cancellous bone mass and architecture in the tibial metaphysis, as well as cortical bone mass and architecture in the tibial diaphysis, were evaluated by micro-CT.

RESULTS

Oral genistein administered as a dietary supplement did not influence the cumulative effects of ovariectomy, aging, and/or reproductive history on cancellous and cortical bone mass and architecture.

CONCLUSIONS

Serum levels of genistein similar to those in women consuming a high-soy diet are ineffective in preventing or treating bone loss in rat models for postmenopausal osteoporosis.

Bone selective protective effect of a novel bone-seeking estrogen on trabecular bone in ovariectomized rats

The drawbacks of estrogen restrict the clinical use of hormone replacement therapy, and it would be most helpful to explore new estrogenic substances that could prevent bone loss and be free from any adverse effects. We synthesized a new compound named bone-seeking estrogen (SE2) by combining 17β-estradiol (E2) with iminodiacetic acid through the Mannich reaction. E2 and SE2 were labeled with isotope (3)H, and the tissue distribution tests of E2-(3)H and SE2-(3)H were analyzed by the radioactivity. The specific nuclear binding of E2 and SE2 in osteoblasts was measured. SE2 exhibited significantly greater affinity for bone but lower affinity for ovary and uterus than did E2, and SE2 maintained a high affinity for the estrogen receptor alpha similar to that of E2. SE2 administration did not induce uterine hypertrophy. Body weight increase was significantly suppressed by treatment with E2 but not by SE2 after ovariectomy (OVX). SE2 decreased bone turnover as E2 after OVX detected by serum biochemical markers. Bone histology and micro-CT analysis revealed that SE2 administration, similar to E2, could improve bone mass and trabecular architecture after OVX. Biomechanical analyses showed that SE2 treatment effectively increased mechanical properties after OVX. The results suggested that SE2 was effective in preventing OVX-induced bone loss and exhibited few side effects on body weight and uterine hypertrophy, which was beneficial in reducing the adverse effects caused by E2. SE2 may be a better choice than E2 for the prevention of postmenopausal osteoporosis.

The effect of soy-derived isoflavones over hot flushes, menopausal symptoms and mood in climacteric women with increased body mass index

BACKGROUND

Risk-benefit issues raised after the WHI have significantly increased the use of alternative treatments for the menopause. Despite this, data regarding the effect of soy isoflavones over mood and menopausal symptoms in high risk populations is still lacking.

OBJECTIVE

To evaluate the effect of soy derived isoflavones over hot flushes, menopausal symptoms and mood in climacteric women with increased body mass index (BMI).

METHODS

Fifty symptomatic climacteric women aged 40 to 59 with increased BMI (≥ 25) were recruited to receive oral 100 mg/day of soy derived isoflavones (Climasoy) for 3 months. Hot flushes (frequency/intensity), menopausal symptoms (Menopause Rating Scale [MRS]) and mood (Hamilton Depressive Rating Scale [HDRS]) were evaluated at baseline and at 90 days.

RESULTS

A total of 45 women completed the study. After 3 months of soy isoflavone supplementation hot flushes significantly decreased in percentage, number and severity (100% to 31.1%; 3.9 ± 2.3 to 0.4 ± 0.8 and 2.6 ± 0.9 to 0.4 ± 0.8, respectively, p < 0.001). MRS scores (total and for subscales) reflecting general menopausal symptoms also significantly decreased compared to baseline. Regarding mood, after three months total HDRS scores and the rate of women presenting depressed mood (scores ≥ 8) significantly decreased (16.3 ± 5.4 to 6.9 ± 5.2 and 93.3% to 28.9%, respectively, p < 0.05). There was no effect on blood pressure levels or BMI values after treatment.

CONCLUSION

In this high risk climacteric population, soy derived isoflavone treatment improved mood as well as vasomotor and general menopausal symptoms. More research is required to determine if the positive effect over mood is a direct or an indirect one through hot flush alleviation.

Effects of soy protein and isoflavones on circulating hormone concentrations in pre- and post-menopausal women: a systematic review and meta-analysis

BACKGROUND

Hormonal effects of soy and isoflavones have been investigated in numerous trials with equivocal findings. We aimed to systematically assess the effects of soy and isoflavones on circulating estrogen and other hormones in pre- and post-menopausal women.

METHODS

The Cochrane Library, MEDLINE and EMBASE (plus reviews and experts) were searched to December 2007. Inclusion of randomized or residential crossover trials of soy or isoflavones for 4 or more weeks on estrogens, SHBG, FSH, LH, progesterone and thyroid hormones in women was assessed independently in duplicate. Six percent of papers assessed were included. Data concerning participants, interventions, outcomes, potential effect modifiers and trial quality characteristics were extracted independently in duplicate.

RESULTS

Forty-seven studies (11 of pre-, 35 of post- and 1 of perimenopausal women) were included. In premenopausal women, meta-analysis suggested that soy or isoflavone consumption did not affect primary outcomes estradiol, estrone or SHBG concentrations, but significantly reduced secondary outcomes FSH and LH [by ∼20% using standardized mean difference (SMD), P = 0.01 and 0.05, respectively]. Menstrual cycle length was increased by 1.05 days (95% CI 0.13, 1.97, 10 studies). In post-menopausal women, there were no statistically significant effects on estradiol, estrone, SHBG, FSH or LH, although there was a small statistically non-significant increase in total estradiol with soy or isoflavones (∼14%, SMD, P = 0.07, 21 studies).

CONCLUSIONS

Isoflavone-rich soy products decrease FSH and LH in premenopausal women and may increase estradiol in post-menopausal women. The clinical implications of these modest hormonal changes remain to be determined.

[Treatment with isoflavones replaces estradiol effect on the tissue fat accumulation from ovariectomized rats]

OBJECTIVE

Isoflavones (ISO) present in soybean are named phytoestrogens because they show estrogen effect. The use of isoflavones has beneficial effect in disturbance of post-menopause, which is characterized by ovarian function suppression. Decreasing of estrogen secretion and consequent morphologic and metabolic disarrangements are observed in female hormonal decline. The aim of present work was to investigate the effect of ISO on the fat accretion of uterine endometric tissue, and HDL and glucose blood concentration from ovariectomized rats (OVX).

METHODS

Female Wistar rats with 60 days-old were submitted a surgery to remove bilaterally the ovarium. After 8-day recovery period the animals were distributed into three groups: sham operate (GC); OVX ISO untreated (GI) and OVX supplemented with ISO (G II). Total uterus mass, uterus fat and retroperitoneal fat pad, were removed, washed and weighted. Samples of uterus were histological processed to measure endometrium thickness. Blood samples were also collected to analyze the concentration of HDL and glucose. The OVX caused endometric atrophy, decrease of uterus weight and HDL reduction. The treatment with ISO provoked decrease of uterine and retroperitoneal fat pad. HDL increase and glycemia reduction were also observed. However, there was no uterotrophic effect.

CONCLUSIONS

ISO treatment causes decrease in tissue fat accretion from ovariectomized rats.

Modulation of basal and squamous cell carcinoma by endogenous estrogen in mouse models of skin cancer

Patched1 heterozygous mice (Ptch1(+/-)) are useful for basal cell carcinoma (BCC) studies, being remarkably susceptible to BCC induction by ultraviolet or ionizing radiation. Analogously, skin carcinogenesis-susceptible (Car-S) mice are elective for studies of papilloma and squamous cell carcinoma (SCC) induction. We previously reported a striking effect of gender on BCC induction in Ptch1(+/-) mice, with total resistance of females; likewise, Car-S females show increased skin tumor resistance relative to males. Here, we investigated the protective role of endogenous estrogen in skin keratinocyte tumorigenesis. Control (CN) and ovariectomized Ptch1(+/-) or Car-S females were irradiated for BCC induction or topically treated with chemical carcinogens for SCC induction. Susceptibility to BCC or SCC was dramatically increased in ovariectomized Ptch1(+/-) and Car-S females and restored to levels observed in males. Remarkably, progression of initially benign papillomas to malignant SCC occurred only in ovariectomized Car-S females. We explored the mechanisms underlying tumor progression and report overexpression of estrogen receptor (ER)-alpha, downregulation of ERbeta and upregulation of cyclin D1 in papillomas from ovariectomized Car-S relative to papillomas from CN females. Thus, an imbalanced ERalpha/ERbeta expression may be associated with estrogen-mediated modulation of non-melanoma skin carcinogenesis, with a key role played by cyclin D1. Our findings underscore a highly protective role of endogenous estrogen against skin tumorigenesis by diverse agents in two independent mouse models of skin cancer.

17beta-Estradiol and soy phytochemicals selectively induce a type 2 polarization in mesenteric lymph nodes of ovariectomized rats

OBJECTIVE

This study was designed to compare the effects of 17beta-estradiol (17beta-E2) and a phytoestrogen-containing soy extract on the immune system in an ovariectomized rat model of menopause. Specifically, T- and B-lymphocyte subsets, the balance of type 1 and 2 immune responses in the mesenteric lymph nodes, and serum levels of different classes of immunoglobulin were examined as study endpoints.

DESIGN

Ovariectomized rats were treated with either the phytoestrogen-containing soy extract (50 or 100 mg/kg/day PO), 17beta-E2 (0.5 mg/kg/day PO), or vehicle; a sham control was included in the study. After the rats were killed, mesenteric lymph nodes and blood samples were collected. B- and T (CD4 and CD8)-lymphocyte subsets in mesenteric lymph nodes were evaluated by flow cytometry analysis. Cytokine-producing T lymphocytes were identified within each T-lymphocyte subset as TH1 (interferon-gamma CD4), TH2 (interleukin-4 CD4), TC1 (interferon-gamma CD8), and TC2 (interferon-4 CD8) lymphocytes. Serum levels of immunoglobulin classes were determined by enzyme-linked immunosorbent assay.

RESULTS

There were no differences in the proportions of B lymphocytes and CD4 and CD8 T lymphocytes among groups. Treatment with 17beta-E2 and phytoestrogen-containing soy extract induced a reduction in TH1 and TC1 lymphocytes paralleled by a slight, nonsignificant, increase in the frequency of TH2. Data expressed as TH1/TH2 and TC1/TC2 ratios depicted a significant polarization of local immunity toward a humoral response. Evaluation of immunoglobulin serum levels did not show any significant difference among groups.

CONCLUSIONS

Here we show that estrogens and soy phytochemicals similarly polarize the immune system toward a type 2 immune response in a preclinical model of menopause; our data draw attention to the crucial need to evaluate in clinical studies the potential side effects on the immune system of the complex soy products that are actually consumed in the postmenopausal setting.

Protective effect of apigenin on ovariectomy-induced bone loss in rats

Recent studies have shown that apigenin not only inhibits bone resorption by osteoclasts but also induces osteoclast apoptosis. However, the influence of apigenin on osteoporosis in animals is relatively unknown. The purpose of this study was to examine the bone-protective effects of apigenin in estrogen-deficient ovariectomized rats. Three-month-old female Sprague-Dawley rats were either sham-operated or ovariectomized and fed AIN-93G diet for 7 weeks to induce bone loss. To confirm bone loss, we used a newly developed non-invasive technique involving zoom-in micro-computed tomography. Apigenin was administered at a dose of 10 mg/kg three times a week for 15 weeks. Our results indicate that apigenin not only increased the mineral content and density of the trabecular bone at the neck of the left femur, but also decreased body weight and dietary consumption. Moreover, our biochemical results indicate that apigenin has a positive effect on bone turnover. The present data suggest that apigenin should be considered for use in the treatment of osteoporosis.

Comparative effects of 17beta-estradiol and phytoestrogens in the regulation of endometrial functions in the rodent uterus

The present study aimed at improving our understanding of the effects of 17beta-estradiol and phytoestrogens on the uterine tissue, by evaluating tissue-specific modulation of molecules related to cell-cycle control and angiogenesis. Specifically, the uterine expression of Ki67, peroxisome proliferator-activated receptor gamma (PPARgamma), and vascular endothelial growth factor receptor-2 (VEGFR-2), was examined by immunohistochemical analysis. Ovariectomized (OVX) rats were treated with either the vehicle, a phytoestrogen- containing soy extract (SSE) (100 mg/kg/day pos), or 17beta-estradiol (0.5 mg/kg/day pos); a sham control group (SHAM) was also included in the study. At necropsy, uteri were weighed, collected, and subsequently processed for histopathology or immunohistochemistry. SSE-treated rats did not show any significant change either in the weight or in histological features of the uterus when compared to OVX controls; the epithelial expression of proliferation marker Ki67 was seen to be significantly reduced, in comparison to both SHAM and OVX rats. Conversely, 17beta-estradiol significantly increased uterine weight, induced hyperplasia in the majority of rats, and enhanced Ki67 epithelial expression. The regulation of PPARgamma expression, reduced after ovariectomy, was similar in SSE- and 17beta-estradiol-treated rats, showing a further significant decrease in stromal immunostaining, in comparison to OVX controls. VEGFR-2 epithelial immunostaining, slightly reduced following ovariectomy, was highly increased on 17beta-estradiol treatment, while following SSE, the pattern of staining observed was similar to that of OVX controls. Data from this study show that PPARgamma and VEGFR-2 represent additional targets by which sex steroid estrogen and plant-derived phytoestrogens may, at certain doses, differentially regulate endometrial functions.

Isoflavones--safe food additives or dangerous drugs?

The sales volume of products containing isoflavone has increased since the publication of the Women's Health Initiative. The many apparently contradictory results published on the effects of isoflavones on a variety of estrogen-regulated organs point to both beneficial as well as adverse effects on human health. It is of particular importance that psychovegetative climacteric complaints such as hot flushes are, if at all, only slightly influenced by isoflavones. The substances appear to have weak anti-osteoporotic effect. Their anti-atherosclerotic action is debatable, as not all authors find any beneficial effect on lipids. Most importantly, there is dispute as to whether isoflavones derived from soy or red clover have negative, positive or any effect at all on the mammary gland or endometrium. It is beyond any doubt that soy products may have cancer preventing properties in a variety of organs including the mammary gland. However, these properties may only be exerted if the developing organ was under the influence of isoflavones during childhood and puberty. This may also explain the often quoted "Japanese Phenomenon", the fact that breast cancer occurs to a lesser extent in Japanese women. When administered to isoflavone "inexperienced" women at the time of menopause, the phytoestrogens appear to share the same effects as estrogen used in classical preparations for hormone replacement therapy, i.e. they may stimulate the proliferation of endometrial and mammary gland tissue with at present unknown and unpredictable risk to these organs. Therefore, the following question arises for the clinician: Why should soy or red clover products containing isoflavone be recommended, if the positive effects are only negligible but the adverse effects serious?

Lack of stimulatory activity of a phytoestrogen-containing soy extract on the growth of breast cancer tumors in mice

The present study was designed to investigate the effects of a phytoestrogens-containing soy extract (SOYSELECT, SSE) on the growth of estrogen-dependent (MCF-7) and estrogen-unresponsive (MDA-MB-231) human breast cancer xenografts in athymic mice. Results obtained provided evidence that MCF-7 tumors did not grow over the treatment period (5 weeks) in ovariectomized females receiving 50 or 100 mg/kg/day SSE (oral route); administration of SSE also did not affect the estradiol-sustained growth of MCF-7 tumors in mice. Similarly, no effects on tumor growth were observed in SSE-treated mice bearing MDA-MB-231 xenografts. Data from pS2, progesterone receptor and cyclin D1 mRNA expression in tumors showed that, although SSE was able to induce a moderate estrogenic effect in MCF-7 cells, it did not increase cellular proliferation and tumor growth, in our experimental conditions. Besides, when used in association with 17beta-estradiol, it displayed antiestrogenic activity. The expression of other genes involved in tumor progression and angiogenesis, such as Thrombospondin 1, Transforming Growth Factor beta2 and Kallikrein 6 was also evaluated in tumor samples, results showing a decrease in mRNA expression upon SSE treatment. The effect of SSE on angiogenesis in vivo was also evaluated in the Matrigel plug assay; results obtained showed a striking anti-angiogenic activity in mice receiving 100 mg/kg/day SSE, thereby confirming that this extract may interfere with angiogenesis. Collectively, these experimental data suggest that SSE could be not harmful for women with a history of or at high risk for breast cancer, at least for short treatment periods; however, further studies are needed to thoroughly characterize the activity profile of the extract in this specific setting of patients.

Estradiol and phytoestrogens differently influence the rodent postmenopausal mammary gland

OBJECTIVE

In the following study, we investigated treatment-related changes in mammary gland histomorphology and structure after the administration of soy to adult virgin ovariectomized (OVX) female rats. Additionally, mammary receptor regulation was extensively evaluated by immunohistochemical analysis, and tissue proliferative activity analyzed by cell nuclear proliferating antigen expression (Ki67).

DESIGN

OVX rats were treated, for 6 weeks, with either the vehicle, the soy extract (SSE 100 mg/kg/d PO), or 17beta-estradiol (0.5 mg/kg/d PO); a sham control group (SHAM) was also included in the study. When killed, mammary glands were collected and subsequently processed for light microscopy or immunohistochemistry. Immunoreactivity was quantified by a scoring system that took into account both the percentage of positive cells and the intensity of the staining.

RESULTS

The 17beta-estradiol--treated rats had stimulated mammary glands compared with OVX rats, with an average lobulo-alveolar development not different from the SHAM controls. Only a partial regression of the glandular atrophy was observed in OVX rats receiving 100 mg/kg/d SSE, with a histological appearance between that of the OVX and SHAM controls. No significant changes were observed among experimental groups in the median ERalpha scores of the epithelial compartment (score of 3 in all groups); in the stromal compartment, a tendency toward decreased expression was seen with 17beta-estradiol rats compared with OVX controls (scores of 2 and 5, respectively). A significant reduction in ERbeta immunostaining was observed in the mammary glands of SSE-treated rats, in both epithelium and stroma (scores of 4 and 3, respectively), compared with those of OVX controls (score of 8 in both compartments). The ERbeta receptor status was not significantly affected by 17beta-estradiol. Compared with OVX rats (score of 1), PR expression was up-regulated by 17beta-estradiol (score of 6), whereas an ovariectomy-like pattern was observed after the administration of SSE (score of 0). Ki67 immunoreactivity in the epithelium and stroma was increased by the administration of 17beta-estradiol (scores of 4 and 5, respectively) and was unchanged after SSE treatment (scores of 0 and 2, respectively), compared with OVX controls (scores of 1 and 2, respectively).

CONCLUSIONS

The differences observed in the histological pattern, hormonal receptor status regulation, and Ki67 modulation suggest a different role for phytoestrogens and 17beta-estradiol in postmenopausal rodent mammary glands.