Differential effects of isoflavones on bone formation in growing male and female mice

Potential therapeutic interventions of plant-derived isoflavones against acute lung injury

Acute lung injury (ALI) is a life-threatening syndrome that possibly leads to high morbidity and mortality as no therapy exists. Several natural ingredients with negligible adverse effects have recently been investigated to possibly inhibit the inflammatory pathways associated with ALI at the molecular level. Isoflavones, as phytoestrogenic compounds, are naturally occurring bioactive compounds that represent the most abundant category of plant polyphenols (Leguminosae family). A broad range of therapeutic activities of isoflavones, including antioxidants, chemopreventive, anti-inflammatory, antiallergic and antibacterial potentials, have been extensively documented in the literature. Our review exclusively focuses on the possible anti-inflammatory, antioxidant role of botanicals'-derived isoflavones against ALI and their immunomodulatory effect in experimentally induced ALI. Despite the limited scope covering their molecular mechanisms, isoflavones substantially contributed to protecting from ALI via inhibiting toll-like receptor 4 (TLR4)/Myd88/NF-κB pathway and subsequent cytokines, chemokines, and adherent proteins. Nonetheless, future research is suggested to fill the gap in elucidating the protective roles of isoflavones to alleviate ALI concerning antioxidant potentials, inhibition of the inflammatory pathways, and associated molecular mechanisms.

Dry-Fermented Soybean Food (Cheonggukjang) Ameliorates Senile Osteoporosis in the Senescence-Accelerated Mouse Prone 6 Model

Senile osteoporosis increases the risk of skeletal fractures with age. Cheonggukjang (CGJ), a traditional Korean dry fermented soybean product, has numerous therapeutic effects; however, its effects on bone mineral density (BMD) and bone metabolism in senile osteoporosis are unclear. In this study, we treated the senescence-accelerated mouse prone 6 (SAMP6) model of senile osteoporosis with CGJ to determine its potential for ameliorating and preventing osteoporosis progression. High-performance liquid chromatography analysis for isoflavone profiles revealed that short-term fermentation significantly increased the isoflavone aglycone content in soybeans. Thereafter, we fed 6-week-old SAMP6 mice with experimental diets containing 5% or 10% CGJ for 15 weeks. Microcomputed tomography revealed that CGJ supplementation effectively increased the BMD and relative bone length. In vitro, CGJ increased the osteopontin reactivity and upregulated the expression of Alp, Col1a1, Fak, Bmp2/4, Smad1/5/8, and Runx2 in osteoblasts, and decreased Cathepsin K reactivity and downregulated Rankl and Nfatc1 expression in osteoclasts. In addition, CGJ increased the osteoprotegerin/Rankl ratio. Collectively, these results demonstrate that CGJ can ameliorate the detrimental effects of senile osteoporosis by improving osteogenesis and decreasing osteoclast activity.

Assessment of safety and efficacy of perinatal or peripubertal exposure to daidzein on bone development in rats

Neonatal exposure to isoflavones improved bone health in thereafter in previous animal studies. However, since isoflavones possess hormonal activity, it may interfere with reproductive development. In the present study, we assessed the safety and efficiency of perinatal or peripubertal exposure to daidzein on bone and reproductive organ development at early adulthood in rats. Sprague-Dawley pregnant rats (n = 18) were divided into 3 groups: (1) dams and their offspring were fed the control diet. (2) Dams were fed the daidzein diet (0.5 g daidzein/kg diet) during pregnancy and then the control diet at postnatal day 13 and their offspring were fed the control diet. (3) Dams and their offspring were fed the daidzein diet through the experiment. While perinatal exposure to daidzein did not confer a positive effect on bone mineral density on postnatal day 35, peripubertal exposure to daidzein protected against a decline in bone mineral density. Meanwhile, exposure to daidzein during the perinatal or peripubertal period did not affect reproductive organ weights at early adulthood in rats. Further investigations should assess the mechanisms underlying these responses of bone metabolism to daidzein, as well as the safety of daidzein exposure during the perinatal period and throughout life.

Computer-Automated Static, Dynamic and Cellular Bone Histomorphometry

Dynamic and cellular histomorphometry of trabeculae is the most biologically relevant way of assessing steady state bone health. Traditional measurement involves manual visual feature identification by a trained and qualified professional. Inherent with this methodology is the time and cost expenditure, as well as the subjectivity that naturally arises under human visual inspection. In this work, we propose a rapidly deployable, automated, and objective method for dynamic histomorphometry. We demonstrate that our method is highly effective in assessing cellular activities in distal femur and vertebra of mice which are injected with calcein and alizarin complexone 7 and 2 days prior to sacrifice. The mineralized bone tissues of mice are cryosectioned using a tape transfer protocol. A sequential workflow is implemented in which endogenous fluorescent signals (bone mineral, green and red mineralization lines), tartrate resistant acid phosphatase identified by ELF-97 and alkaline phosphatase identified by Fast Red are captured as individual tiled images of the section for each fluorescent color. All the images are then submitted to an image analysis pipeline that automates identification of the mineralized regions of bone and selection of a region of interest. The TRAP and AP stained images are aligned to the mineralized image using strategically placed fluorescent registration beads. Fluorescent signals are identified and are related to the trabecular surface within the ROI. Subsequently, the pipelined method computes static measurements, dynamic measurements, and cellular activities of osteoclast and osteoblast related to the trabecular surface. Our method has been applied to the distal femurs and vertebrae of 8 and 16 week old male and female C57Bl/6J mice. The histomorphometric results reveal a significantly greater bone turnover rate in female in contrast to male irrespective of age, validating similar outcomes reported by other studies.

Beneficial effects of phytoestrogens and their metabolites produced by intestinal microflora on bone health

Phytoestrogens are a class of bioactive compounds derived from plants and exert various estrogenic and antiestrogenic effects. Estrogen deficiency osteoporosis has become a serious problem in elderly women. The use of ovariectomized (OVX) rat or mice models to simulate the postmenopausal condition is well established. This review aimed to clarify the sources, biochemistry, absorption, metabolism, and mode of action of phytoestrogens on bone health in intervention studies. In vitro, phytoestrogens promote protein synthesis, osteoprotegerin/receptor activation of nuclear factor-kappa B ligand ratio, and mineralization by osteoblast-like cells (MC3T3-E1). In the OVX murine model, administration of phytoestrogens can inhibit differentiation and activation of osteoclasts, expression of tartrate-resistant acid phosphatase, and secretion of pyridinoline compound. Phytoestrogens also enhance bone formation and increase bone mineral density and levels of alkaline phosphatase, osteocalcin, osteopontin, and α1(I) collagen. Results of mechanistic studies have indicated that phytoestrogens suppress the rate of bone resorption and enhance the rate of bone formation.

Use of Awamori-pressed Lees and Tofu Lees as Feed Ingredients for Growing Female Goats

Okinawan Awamori is produced by fermenting steamed indica rice with black mold, yeast, and water. Awamori-pressed lees is a by-product of the Awamori production process. Tofu lees is a by-product of the Tofu production process. This research consisted of two experiments conducted to elucidate whether or not dried Awamori-pressed lees and Tofu lees can be used as a mixed feed ingredient for raising female goats. In experiment 1, digestion trials were conducted to ascertain the nutritive values of dried Awamori-pressed lees and dried Tofu lees for goats. The digestible crude protein (DCP) and total digestible nutrients (TDN) contents of dried Awamori-pressed lees and Tofu lees were 22.5%, 22.5% (DCP), and 87.2%, 94.4% (TDN) respectively. In experiment 2, 18 female goats (Japanese Saanen×Nubian, three months old, body weight 15.4±0.53 kg) were divided into three groups of six animals (control feed group (CFG), Awamori-pressed lees mixed feed group (AMFG), Tofu lees mixed feed group (TMFG)). The CFG control used feed containing 20% soybean meal as the main protein source, while the AMFG and TMFG treatments used feed mixed with 20% dried Awamori-pressed lees or dried Tofu lees. The groups were fed mixed feed (volume to provide 100 g/d increase in body weight) twice a day (10:00, 16:00). The klein grass hay and water was given ad libitum. The hay intake was measured at 08:00 and 16:00. Body weight and size measurements were taken once a month. At the end of the experiment, a blood sample was drawn from the jugular vein of each animal. The DCP and TDN intakes in AMFG and TMFG showed no significant difference to the CFG. Cumulative measurements of growth in body weight, withers height, chest depth, chest girth, and hip width over the 10 mo period in the AMFG and TMFG were similar to the CFG. By contrast, cumulative growth in body length and hip height in the AMFG and TMFG tended to be larger than the CFG. Cumulative growth in chest width in the AMFG was significantly larger (p<0.05) than the CFG. Blood parameter values were similar to those in normal goats reported by other scientists. The coats of the AMFG and TMFG animals looked shinier than the animals in the CFG. The results demonstrate that dried Awamori-pressed lees and Tofu lees can be used as a feed ingredient for the raising female goats.

Resistant starch promotes equol production and inhibits tibial bone loss in ovariectomized mice treated with daidzein

Daidzein is metabolized to equol in the gastrointestinal tract by gut microflora. Equol has greater estrogenic activity than genistein and daidzein, with its production shown to be promoted by dietary fiber. It is known that resistant starch (RS) is not absorbed in the proximal intestine and acts as dietary fiber in the colon. In this study, we investigated the combined effects of daidzein and RS intake on equol production, bone mineral density, and intestinal microflora in ovariectomized (OVX) mice. Female mice of the ddY strain, aged 8 weeks, were either sham operated (n = 6) or OVX. The OVX mice were randomly divided into 5 groups: OVX control (n = 6), OVX fed 0.1% daidzein-supplemented diet (OVX + Dz, n = 8), OVX fed 0.1% daidzein- and 12% RS-supplemented diet (OVX + Dz + RS, n = 8), OVX fed 12% RS-supplemented diet (OVX + RS, n = 8), and OVX who received daily subcutaneous administration of 17 β-estradiol (n = 6). After 6 weeks, urinary equol concentration was significantly higher in the OVX + Dz + RS group than in the OVX + Dz group. The bone mineral density of the whole tibia was higher in the OVX + Dz +RS group compared with the OVX + Dz group. The occupation ratios of Bifidobacterium spp in the cecal microflora in groups fed RS were significantly higher than those in the other groups. The present study demonstrated that RS may increase the bioavailability of daidzein.

Medicarpin, a legume phytoalexin, stimulates osteoblast differentiation and promotes peak bone mass achievement in rats: evidence for estrogen receptor β-mediated osteogenic action of medicarpin

Dietary isoflavones including genistein and daidzein have been shown to have favorable bone conserving effects during estrogen deficiency in experimental animals and humans. We have evaluated osteogenic effect of medicarpin (Med); a phytoalexin that is structurally related to isoflavones and is found in dietary legumes. Med stimulated osteoblast differentiation and mineralization at as low as 10⁻¹⁰ M. Studies with signal transduction inhibitors demonstrated involvement of a p38 mitogen activated protein kinase-ER-bone morphogenic protein-2 pathway in mediating Med action in osteoblasts. Co-activator interaction studies demonstrated that Med acted as an estrogen receptor (ER) agonist; however, in contrast to 17β-estradiol, Med had no uterine estrogenicity and blocked proliferation of MCF-7 cells. Med increased protein levels of ERβ in osteoblasts. Selective knockdown of ERα and ERβ in osteoblasts established that osteogenic action of Med is ERβ-dependent. Female Sprague-Dawley (weaning) rats were administered Med at 1.0- and 10.0 mg.kg⁻¹ doses by gavage for 30 days along with vehicle control. Med treatment resulted in increased formation of osteoporgenitor cells in the bone marrow and osteoid formation (mineralization surface, mineral apposition/bone formation rates) compared with vehicle group. In addition, Med increased cortical thickness and bone biomechanical strength. In pharmacokinetic studies, Med exhibited oral bioavailability of 22.34% and did not produce equol. Together, our results demonstrate Med stimulates osteoblast differentiation likely via ERβ, promotes achievement of peak bone mass, and is devoid of uterine estrogenicity. In addition, given its excellent oral bioavailability, Med can be potential osteogenic agent.

Medicarpin inhibits osteoclastogenesis and has nonestrogenic bone conserving effect in ovariectomized mice

Medicarpin, a pterocarpan class of naturally occurring benzopyran furanobenzene compound was synthesized in gram scale to investigate its effects on murine bone cells and in ovariectomized (OVx) mice. Medicarpin, at as low as 10(-10)M suppressed osteoclastogenesis in bone marrow cells (BMCs). Medicarpin-induced apoptosis of mature osteoclasts isolated from long bones. Effects of medicarpin in osteoclasts appear to be independent of estrogen receptor (ER) activation as ICI 180,782 failed to abrogate its effects on osteoclasts. In calvarial osteoblasts, medicarpin (10(-10)M) blocked nuclear factor kappaB (NF-kappaB) signaling assessed by tumor necrosis factor alpha (TNFalpha)-stimulated nuclear translocation of p65 subunit of NF-kappaB. Medicarpin also inhibited the expression of TNFalpha in mouse calvarial osteoblasts. This effect was ER dependent as ICI 180,782 reversed the suppressive effect of medicarpin on TNFalpha mRNA levels in osteoblasts. In addition, like 17beta-estradiol, presence of medicarpin inhibited TNFalpha-induced upregulation of interleukin-1, and -6 mRNA levels in osteoblasts. In co-cultures consisting of calvarial osteoblasts and BMCs, presence of medicarpin increased osteoprotegerin (OPG)/receptor activator of NF-kappaB ligand (RANKL) ratio and reduced mRNA levels of osteoclast markers including tartrate-resistant acid phosphatase and RANK. OVx mice administered medicarpin (10.0mgkg(-1)day(-1)) orally for 30days had reduced formation of osteoclasts but increased formation of osteoprogenitor cells in BMCs compared with OVx+vehicle group. Medicarpin treatment to OVx mice maintained parameters of trabecular microarchitecure. Medicarpin exhibited no uterine estrogenicity. Our findings point towards direct and indirect inhibitory effects of medicarpin on osteoclastogenesis in vitro that contribute to its bone sparing effect in OVx mice.

Effect of marine collagen peptides on long bone development in growing rats

BACKGROUND

Nutritional factors play an important role in skeletal development during growth. However, the absorption rates of many bone-related minerals are relatively low from traditional diets, especially for people in Asia and Africa. In the present study, the effect of marine collagen peptides (MCP) derived from chum salmon (Oncorhynchus keta) skin on the development of femurs in growing rats of both sexes was investigated.

RESULTS

MCP supplementation could increase the size, mineral density, dry weight, ash weight, content of most minerals and both stiffness and toughness of femurs in male growing rats. However, such effects were milder in female rats. The reported increase in mineral density was likely to be related to increased osteoblast activity rather than a decreased rate of bone resorption, as an increase in serum osteocalcin and bone-specific alkaline phosphatase content was observed, but no significant difference in serum N-terminal telopeptide of type I collagen compared with control was found.

CONCLUSION

MCP supplementation could promote the development of long bones in growing male rats.

Soybean isoflavone exposure does not have feminizing effects on men: a critical examination of the clinical evidence

OBJECTIVE

To critically evaluate the clinical evidence, and when not available, the animal data, most relevant to concerns that isoflavone exposure in the form of supplements or soy foods has feminizing effects on men.

DESIGN

Medline literature review and cross-reference of published data.

RESULT(S)

In contrast to the results of some rodent studies, findings from a recently published metaanalysis and subsequently published studies show that neither isoflavone supplements nor isoflavone-rich soy affect total or free testosterone (T) levels. Similarly, there is essentially no evidence from the nine identified clinical studies that isoflavone exposure affects circulating estrogen levels in men. Clinical evidence also indicates that isoflavones have no effect on sperm or semen parameters, although only three intervention studies were identified and none were longer than 3 months in duration. Finally, findings from animal studies suggesting that isoflavones increase the risk of erectile dysfunction are not applicable to men, because of differences in isoflavone metabolism between rodents and humans and the excessively high amount of isoflavones to which the animals were exposed.

CONCLUSION(S)

The intervention data indicate that isoflavones do not exert feminizing effects on men at intake levels equal to and even considerably higher than are typical for Asian males.

A newly developed snack effective for enhancing bone volume

BACKGROUND

The incidence of primary osteoporosis is higher in Japan than in USA and European countries. Recently, the importance of preventive medicine has been gradually recognized in the field of orthopaedic surgery with a concept that peak bone mass should be increased in childhood as much as possible for the prevention of osteoporosis. Under such background, we have developed a new bean snack with an aim to improve bone volume loss. In this study, we examined the effects of a newly developed snack on bone volume and density in osteoporosis model mice.

METHODS

Orchiectomy (ORX) and ovariectomy (OVX) were performed for C57BL/6J mice of twelve-week-old (Jackson Laboratory, Bar Harbar, ME, USA) were used in this experiment. We prepared and given three types of powder diet e.g.: normal calcium diet (NCD, Ca: 0.9%, Clea Japan Co., Tokyo, Japan), low calcium diet (LCD, Ca: 0.63%, Clea Japan Co.,) and special diet (SCD, Ca: 0.9%). Eighteen weeks after surgery, all the animals were sacrified and prepared for histomorphometric analysis to quantify bone density and bone mineral content.

RESULTS

As a result of histomorphometric examination, SCD was revealed to enhance bone volume irrespective of age and sex. The bone density was increased significantly in osteoporosis model mice fed the newly developmental snack as compared with the control mice. The bone mineral content was also enhanced significantly. These phenomena were revealed in both sexes.

CONCLUSION

It is shown that the newly developed bean snack is highly effective for the improvement of bone volume loss irrespective of sex. We demonstrated that newly developmental snack supplements may be a useful preventive measure for Japanese whose bone mineral density values are less than the ideal condition.

Dietary soy isoflavone replacement improves detrusor overactivity of ovariectomized rats with altered connexin-43 expression in the urinary bladder

To evaluate the effects of dietary soy isoflavone on detrusor overactivity (DO) in ovariectomized (Ovx) rats and the association between these effects and expression of the gap junction protein, connexin-43, in the urinary bladder, and to discuss the usefulness of soy isoflavones for overactive bladder (OAB).

MATERIALS AND METHODS

In all, 24 (8-week-old) virgin female Sprague-Dawley rats were divided equally into four groups: sham operation with control diet (with no dietary soy isoflavones; Sham-CD), bilateral Ovx with CD (Ovx-CD), sham operation with soy isoflavone diet (Sham-ID), bilateral Ovx with soy ID (Ovx-ID). Cystometry was performed after the 4-week CD or ID in each group while awake. Quantitative reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemical and Western blot analyses were also performed to examine the expression of connexin-43 in each group.

RESULTS

In Ovx-CD rats, there were some significant changes in cystometry variables, including shortening of the intercontraction interval and an increased number of non-voiding contractions compared with Sham-CD rats (P < 0.05). These changes were significantly improved by 4-week soy isoflavone administration (Ovx-ID; P < 0.05). Quantitative RT-PCR, immunohistochemical and Western blot analyses showed that the expression level of connexin-43 mRNA and protein was significantly greater in the urinary bladder of Ovx-CD rats compared with Sham-CD rats. Soy isoflavone administration significantly reduced this increased expression (Ovx-ID).

CONCLUSIONS

Soy isoflavone replacement improved DO with alteration of the connexin-43 expression pattern in the urinary bladder of Ovx rats. Routine consumption of diet soy isoflavones may be a useful treatment to prevent and improve OAB.

Functional food science and food for specified health use policy in Japan: state of the art

PURPOSE OF REVIEW

The science and policy of functional foods are a matter of global concern and this review provides up-to-date information about the Japanese 'food for specified health use' policy based on functional food science.

RECENT FINDINGS

A great many studies on nonnutritive but physiologically functional food components have provided more precise evidence regarding the structure-function relationships that underlie the approval of food for specified health use products.

SUMMARY

Functional foods, defined as those that have the potential to reduce the risk of lifestyle-related diseases and associated abnormal modalities, have garnered global interest since the 1980s when the systematic research had humble beginnings as a national project in Japan. In 1991, the project led to the launch of the national food for specified health use policy; 703 food for specified health use products with 11 categories of health claims have been approved up to the present (31 August 2007). The development of this policy has been supported basically by nutritional epidemiology, food chemistry and biochemistry, physiology and clinical medicine, and even the genomics on food and nutrition. This review also highlights the current academia-industry collaboration in Japan.