Ipriflavone, a synthetic phytoestrogen, enhances intestinal calcium transport in vitro

Phoenix dactilyfera L. Pits Extract Restored Bone Homeostasis in Glucocorticoid-Induced Osteoporotic Animal Model through the Antioxidant Effect and Wnt5a Non-Canonical Signaling

Oxidative stress associated with long-term glucocorticoids administration is a route through which secondary osteoporosis can be developed. The therapeutic potential of Phoenix dactilyfera L. pits is offered by their balanced, valuable and diverse phytochemical composition providing protective potential against oxidative reactions, making it a good candidate to treat glucocorticoid-induced osteoporosis (GIO). This study evaluates the possible anti-osteoporotic effect of date pit extract (DPE) against dexamethasone (DEXA)-induced osteoporosis. Male rats were allocated into three control groups, which received saline, low and high doses of DPE (150 and 300 mg/kg/day), respectively. Osteoporosis-induced groups that received DEXA (1 mg/kg/day) were divided into DEXA only, DPE (2 doses) + DEXA, and ipriflavone + DEXA. Femoral bone minerals density and bone mineral content, bone oxidative stress markers, Wnt signaling, osteoblast and osteoclast differentiation markers, and femur histopathology were evaluated. DPE defeated the oxidative stress, resulting in ameliorative changes in Wnt signaling. DPE significantly reduced the adipogenicity and abolished the osteoclastogenic markers (RANKL/OPG ratio, ACP, TRAP) while enhancing the osteogenic differentiation markers (Runx2, Osx, COL1A1, OCN). In Conclusion DPE restored the balanced proliferation and differentiation of osteoclasts and osteoblasts precursors. DPE can be considered a promising remedy for GIO, especially at a low dose that had more potency.

Potential of Mulberry Leaf Biomass and Its Flavonoids to Improve Production and Health in Ruminants: Mechanistic Insights and Prospects

Leaf biomass from the mulberry plant (genus Morus and family Moraceae) is considered a potential resource for livestock feeding. Mulberry leaves (MLs) contain high protein (14.0-34.2%) and metabolizable energy (1130-2240 kcal/kg) with high dry matter (DM) digestibility (75-85%) and palatability. Flavonoid contents of MLs confer unique antioxidant properties and can potentially help alleviate oxidative stress in animals during stressful periods, such as neonatal, weaning, and periparturient periods. In addition, mulberry leaf flavonoids (MLFs) possess antimicrobial properties and can effectively decrease the population of ruminal methanogens and protozoa to reduce enteric methane (CH4) production. Owing to its rich flavonoid content, feeding MLs increases fiber digestion and utilization leading to enhanced milk production in ruminants. Dietary supplementation with MLFs alters ruminal fermentation kinetics by increasing total volatile fatty acids, propionate, and ammonia concentrations. Furthermore, they can substantially increase the population of specific cellulolytic bacteria in the rumen. Owing to their structural homology with steroid hormones, the MLFs can potentially modulate different metabolic pathways particularly those linked with energy homeostasis. This review aims to highlight the potential of ML and its flavonoids to modulate the ruminal microbiome, fermentation, and metabolic status to enhance productive performance and health in ruminants while reducing CH4 emission.

Mulberry Leaf Flavonoids Improve Milk Production, Antioxidant, and Metabolic Status of Water Buffaloes

This study was aimed to evaluate the effect of mulberry leaf flavonoids (MLF) on oxidative stress, metabolic hormones, and milk production in Murrah buffaloes. Forty multiparous Murrah buffaloes (4 ± 1 lactations) with similar body weight (average 600 ± 50 Kg) and stage of lactation (90 ± 20 d) were randomly selected for this trial. Four treatment groups (10 buffaloes per group) with different doses of MLF included; control (0 g/d), MLF15 (15 g/d), MLF30 (30 g/d), and MLF45 (45 g/d). Buffaloes were fed with total mix ration consisting of grass (Pennisetum purpureum schum), brewery's grain and concentrate mixture for 5 weeks. Meteorological data including ambient temperature and relative humidity were recorded using the online dust monitoring system to calculate temperature-humidity index (THI). After 1 week of the adaptation, milk yield was recorded daily while physiological parameters (respiratory rate, rectal, and body surface temperature), and milk composition were measured weekly. At the end of the trial, blood samples were collected to analyze serum metabolic hormones including estradiol (E2), growth hormone (GH), prolactin (PRL), Tri-iodothyronine (T3), and Thyroxine (T4). Moreover, serum heat shock proteins (HSP), antioxidants enzymes including malondialdehyde (MDA), total antioxidant capacity (T-AOC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) and blood biochemical indices were also analyzed. Results revealed a decrease (P = 0.012) in serum MDA level while increasing (P < 0.01) the HSP and serum GHS-Px contents in supplemented buffaloes. Treatment showed a linear and quadratic decrease (p = 0.001) in the serum T-AOC while reducing CAT contents linearly (p = 0.012) as compared to the control. However, no effect of treatment on serum SOD content was observed. Treatment resulted a linear increase (p = 0.001) in serum GH and PRL hormones while increasing serum E2 levels linearly (P < 0.001) and quadratically (P = 0.025). Treatment increased (p = 0.038) the daily milk yield as compared to the control. However, increase (P < 0.05) in serum T3 and T4 contents, fat corrected milk (4%) and milk protein (%) was observed only in MLF45. Moreover, we observed no change in serum biochemical indices except insulin which linearly increased (p = 0.002) in MLF45. Our findings indicated that MLF at 45 g per day is an appropriate level to enhance milk performance and alleviate heat stress in buffaloes.

Interaction among Calcium Diet Content, PTH (1-34) Treatment and Balance of Bone Homeostasis in Rat Model: The Trabecular Bone as Keystone

The present study is the second step (concerning normal diet restoration) of the our previous study (concerning the calcium-free diet) to determine whether normal diet restoration, with/without concomitant PTH (1-34) administration, can influence amounts and deposition sites of the total bone mass. Histomorphometric evaluations and immunohistochemical analysis for Sclerostin expression were conducted on the vertebral bodies and femurs in the rat model. The final goals are (i) to define timing and manners of bone mass changes when calcium is restored to the diet, (ii) to analyze the different involvement of the two bony architectures having different metabolism (i.e., trabecular versus cortical bone), and (iii) to verify the eventual role of PTH (1-34) administration. Results evidenced the greater involvement of the trabecular bone with respect to the cortical bone, in response to different levels of calcium content in the diet, and the effect of PTH, mostly in the recovery of trabecular bony architecture. The main findings emerged from the present study are (i) the importance of the interplay between mineral homeostasis and skeletal homeostasis in modulating and guiding bone's response to dietary/metabolic alterations and (ii) the evidence that the more involved bony architecture is the trabecular bone, the most susceptible to the dynamical balance of the two homeostases.

Effects of mulberry leaf flavonoid and resveratrol on methane emission and nutrient digestion in sheep

As a new type of methane control agent, natural plant extract has been widely studied in recent years, but in vivo studies are few. This study was to investigate the effects of the dietary supplementation of 2 different polyphenols on the methane (CH₄) emission and digestion metabolism in sheep. Ten healthy crossbred sheep (Dorper ♂ × small-tailed Han ♀; BW 60.0 ± 1.73 kg) were used in a change-over design. The sheep were fed the following 3 diets in the present study: the basal diet (CON) with no supplementation; the basal diet supplemented with 2 g mulberry leaf flavonoid (MLF) per day per sheep; the basal diet supplemented with 0.25 g resveratrol (RES) per day per sheep. Both MLF and RES reduced CH₄ emission scaled to metabolic weight per kilogram of DMI and CO₂ output scaled to metabolic weight, but the effect of RES was significant (P < 0.05). Both MLF and RES significantly improved apparent digestibility of DM, OM, NDF, ADF, and nitrogen, but the effect of RES was significant (P < 0.05). Both MLF and RES significantly improved ME (P < 0.05) and reduced energy losses in CH₄ emission (P > 0.05). In conclusion, MLF and RES can improve the digestibility of nutrients, the utilization of nutrients and energy, and reduce CH₄ emission, but they are not conducive to nitrogen retention.

The Protective and Therapeutic Effect of Exclusive and Combined Treatment with Alpha-ketoglutarate Sodium Salt and Ipriflavone on Bone Loss in Orchidectomized Rats

OBJECTIVE

This study investigated the effect of alpha-ketoglutarate sodium salt (AKG) and ipriflavone (IP) treatment on the mineralization of the tibia in male rats during the development and after the establishment of osteopenia.

DESIGN

One hundred and twenty eight male rats were randomly selected and submitted to either sham-operation (SHO) or orchidectomy (ORX), after which each group were then randomly divided between the two experiments. In Experiment-1, treatment with AKG or/and IP started after a 7-day recovery period, whereas in Experiment-2, the experimental protocol proceeded after a 60-day period of osteopenia establishment. AKG was then administered as an experimental drinking, at a concentration of 1.0 mol/l. As a control, a placebo solution was administered. IP at 50 mg/kg b.w., and physiological saline - PhS (as a control for IP) were applied daily via gavage.

MEASUREMENTS

After 60 days of experimental treatment, in both experiments, the rats were sacrificed, their body weight recorded, while blood serum (Osteocalcin, CTX) and isolated tibia (weight, length, pQCT, DXA, 3-point bending test) were stored for further analysis.

RESULTS AND CONCLUSIONS

Our results show that during the development of osteopenia, AKG and IP when applied exclusively, counteracts osteopenia development, whereas their usage after the establishment of osteopenia, significantly limits the development of bone disorders. Furthermore, combined treatment of AKG and IP exceeded the effects of their sole usage. In addition, during the development of osteopenia, AKG and IP not only inhibited bone resorption, but markedly stimulated the formation of bone tissue. Finally, after the development of osteopenia, combined treatment with AKG and IP protected the bone tissue against orchidectomy-induced bone loss.

Mineral and Skeletal Homeostasis Influence the Manner of Bone Loss in Metabolic Osteoporosis due to Calcium-Deprived Diet in Different Sites of Rat Vertebra and Femur

Rats fed calcium-deprived diet develop osteoporosis due to enhanced bone resorption, secondary to parathyroid overactivity resulting from nutritional hypocalcemia. Therefore, rats provide a good experimental animal model for studying bone modelling alterations during biochemical osteoporosis. Three-month-old Sprague-Dawley male rats were divided into 4 groups: (1) baseline, (2) normal diet for 4 weeks, (3) calcium-deprived diet for 4 weeks, and (4) calcium-deprived diet for 4 weeks and concomitant administration of PTH (1-34) 40 µg/Kg/day. Histomorphometrical analyses were made on cortical and trabecular bone of lumbar vertebral body as well as of mid-diaphysis and distal metaphysis of femur. In all rats fed calcium-deprived diet, despite the reduction of trabecular number (due to the maintenance of mineral homeostasis), an intense activity of bone deposition occurs on the surface of the few remaining trabeculae (in answering to mechanical stresses and, consequently, to maintain the skeletal homeostasis). Different responses were detected in different sites of cortical bone, depending on their main function in answering mineral or skeletal homeostasis. This study represents the starting point for work-in-progress researches, with the aim of defining in detail timing and manners of evolution and recovery of biochemical osteoporosis.

Effects of different doses of ferutinin on bone formation/resorption in ovariectomized rats

This study analyzes the effects of different doses of ferutinin on bone loss caused by estrogen deficiency in ovariectomized rats, in comparison with estradiol benzoate. Thirty female Sprague-Dawley rats were ovariectomized and treated for 30 days from the day after ovariectomy. Static/dynamic histomorphometric analyses were performed on trabecular and cortical bone of lumbar vertebrae and femurs. Very low weight increments were recorded only in all F-OVX groups, with respect to the others. Although the great differences in weight, that could imply a decrease of bone mass in F-OVX groups compared to the control ovariectomized group (C-OVX), trabecular bone in lumbar vertebrae did not show significant differences, suggesting that ferutinin, opposing estrogen deficiency, inhibits bone resorption. Newly formed cortical bone was always low in all F-OVX groups and high in C-OVX, suggesting that it is mainly devoted in answering mechanical demands. In contrast, in distal femoral metaphyses, trabecular bone was reduced and the number of osteoclasts was increased in C-OVX with respect to all other groups, suggesting that it is mainly devoted in answering metabolic demands; moreover, ferutinin dose of 2 mg/kg seemed to be more effective than the lower doses used and estrogens, particularly in those skeletal regions with higher metabolic activity. Our results suggest that the role of ferutinin in preventing osteoporosis caused by estrogen deficiency is expressed in decreasing bone erosion; moreover, in all F-OVX groups bone turnover is very low and seems correlated to the trivial body weight increase, which, in turn, depends on ferutinin treatment.

Mutagenicity of ipriflavone in vivo and in vitro

Ipriflavone (7-isopropoxy-isoflavone) is a semisynthetic isoflavone derivative from daidzein and prescribed to prevent and treat osteoporosis in postmenopausal women. In the present study, ipriflavone was investigated with regard to their cytotoxic and mutagenic effects using the micronucleus assay (MN) in vivo on cells of bone marrow and peripheral blood of Swiss albino mice and the micronucleus test with the cytokinesis-blocked micronucleus assay (CBMN assay) on human peripheral blood lymphocytes. The studies were performed in mice with three dosages of the drug, 1.71, 8.57 and 42.85 mg/kg bw in single oral exposure, and for two dosages, 5 and 10 μg/mL in the CBMN assay. Ipriflavone, in the dosages tested, did not differ from controls neither in the induction of MN nor induced cytotoxicity to cells in the in vivo test. However, in the CBMN assay, the concentration of 10 μg/mL induced a statistically significant increase in MN formation and decreased cell proliferation, demonstrating to be mutagenic and cytotoxic at this concentration.

Effects of estrogen and estrogenic compounds on cognition in ovariectomized rats

OBJECTIVES

To evaluate the effects of estrogen and estrogenic compounds on cognition in ovariectomized rats.

METHODS

Female Sprague-Dawley rats (3-5 months old) weighing 250-300 g were randomly divided into seven groups: Sham, ovariectomized (OVX), OVX plus estradiol valerate, OVX plus ipriflavone, OVX plus raloxifene, OVX plus tibolone, OVX plus low-dose estradiol valerate and ipriflavone. All treatments were given orally for 3 months; whereas the drug groups received indicated drugs, the Sham and OVX control groups received saline. The escape latency of rats was tested by the Morris water maze test and the expression of amyloid precursor protein (APP) in hippocampus was determined by reverse transcription polymerase chain reaction. The level of serum estradiol and the diameter of the endometrial gland and the thickness of endometrium were also evaluated.

RESULTS

The latency of the OVX group was noticeably longer than that of the Sham group, and the latency of all treatment groups was lower than that of OVX rats. The expression of APP mRNA in the hippocampii of OVX rats was significantly increased relative to that in Sham rats; interestingly, expression of APP in treatment groups was significantly reduced relative to OVX rats.

CONCLUSIONS

Our data indicate that estrogenic compounds can antagonize cognitive impairment and that all these compounds cause only mild stimulation on the endometrium compared to estrogen. Inhibition of APP expression in the hippocampus may account for, at least partially, the protective effects of these estrogenic compounds against cognitive defects. Our data suggest that estrogenic compounds (raloxifene, tibolone and ipriflavone) may be a promising approach to antagonize cognitive impairment in postmenopausal women.

Effects of Ipriflavone on Caged Layer Bone Metabolism In Vitro and In Vivo

The effects of ipriflavone on caged layer bone metabolism were examined in vitro and in vivo. Ipriflavone at 10(-8) M stimulated the activity of osteoblasts cultured from embryonic chick calvariae, and 10(-9) to 10(-7) M inhibited osteoclasts from chick tibias and humeri. Ipriflavone concentrations of 10(-4) and 10(-5) M inhibited osteoblast activity. These results suggest that ipriflavone influences bone metabolism by regulating the functional balance between osteoblasts and osteoclasts. Based on these in vitro experiments, in vivo studies were conducted to further clarify the effects of ipriflavone. Five hundred 58-wk-old ISA caged layers were divided into 5 groups that were fed diets containing 0, 15, 25, 50, and 100 ppm of ipriflavone. The experiment lasted 70 d. Egg production increased in hens fed 25 ppm and decreased in hens fed 50 and 100 ppm when compared with the controls and hens fed 15 ppm (P < 0.05). Egg weight, shell quality, BW, and serum P, Ca, estrogen, and bone mineral content were not affected by inclusion of ipriflavone in the diet. Hens consuming 25 ppm of ipriflavone had greater serum alkaline phosphatase and bone gla-protein levels than controls. Adding 25 ppm of ipriflavone to the feed appears to be close to an ideal level for clinical treatment of osteoporosis because of improved egg production while maintaining bone mineral content.

True fractional calcium absorption is decreased after Roux-en-Y gastric bypass surgery

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) is considered to be the gold standard alternative treatment for severe obesity. Weight loss after RYGB results primarily from decreased food intake. Inadequate calcium (Ca) intake and metabolic bone disease can occur after gastric bypass. To our knowledge, whether malabsorption of Ca contributes to an altered Ca metabolism in the RYGB patient has not been addressed previously.

RESEARCH METHODS AND PROCEDURES

We recruited 25 extremely obese women in order to study true fractional Ca absorption (TFCA) before and 6 months after RYGB surgery, using a dual stable isotope method ((42)Ca and (43)Ca) and test load of Ca (200 mg). Hormones regulating Ca absorption and markers of bone turnover were also measured.

RESULTS

In 21 women (BMI 52.7 +/- 8.3 kg/m(2), age 43.9 +/- 10.4 years) who successfully completed the study, TFCA decreased from 0.36 +/- 0.08 to 0.24 +/- 0.09 (p < 0.001) after RYGB. Bone turnover markers increased significantly (p < 0.01). TFCA correlated with estradiol levels (r = 0.512, p < 0.02) and tended to correlate with 1,25 (OH)(2)D (r = 0.427, p < 0.06) at final measurement. Stepwise linear regression indicated that estradiol explained 62% of the variance for TFCA at 6 months post-surgery (p < 0.01).

DISCUSSION

TFCA decreases (0.12 +/- 0.08) after RYGB surgery but remains within normal range. Although only some patients were estimated to have low Ca absorption after surgery, all of the patients showed a dramatic increase in markers of bone resorption. The alteration in Ca metabolism after RYGB-induced weight loss appears to be regulated primarily by estradiol levels and might ultimately affect bone mass.

Effect of 17beta-oestradiol on transepithelial calcium transport in human intestinal-like Caco-2 cells and its interactions with 1,25-dihydroxycholecalciferol and 9-cis retinoic acid

BACKGROUND

Oestrogen therapy helps prevent bone loss in postmenopausal women and corrects a decline in Ca absorption efficiency at the onset of menopause. However, the mechanism by which 17beta-oestradiol (17beta-E2) stimulates Ca absorption is unclear. Oestrogen may exert its effect indirectly via increasing 1,25-dihydroxycholeciferol (1,25 (OH)2D3) or its receptor, or act more directly on the intestines via the oestrogen receptor (OR). Since oestrogen also increases retinol levels, this may influence Ca absorption.

AIM

To investigate the effect of 17beta-E2 alone and in combination with 1,25 (OH)2D3 on intestinal Ca uptake and absorption in Caco-2 cells cultured under deplete- and replete-9-cis retinoic acid (9-cis RA) conditions.

METHODS

Twenty-one day-old Caco-2 cell monolayers (n 9 wells per treatment) were exposed to 9-cis RA-deplete and -replete media containing dimethyl sulfoxide (control), 10 nM-1,25 (OH)2D3, 10 nM-17beta-E2, or 10 nM-1,25 (OH)2D3 plus 10 nM-17beta-E2, for 48 h.

RESULTS

1,25 (OH)2D3 stimulated Ca uptake, total Ca transport, calbindin D(9K) and CaT1 mRNA levels, while 17beta-E2 and 9-cis RA had no effect on Ca absorption or uptake. Nor did they augment the stimulatory effect of 1,25 (OH)2D3.

CONCLUSION

These in vitro findings suggest that oestrogen does not have a direct effect on intestinal Ca absorption.

Role of oil extract of garlic (Allium sativum Linn.) on intestinal transference of calcium and its possible correlation with preservation of skeletal health in an ovariectomized rat model of osteoporosis

The present study was undertaken to examine the effects of an oil extract of garlic on the in vivo intestinal transference of calcium, and also to verify its role in maintaining the bone mineral content and bone tensile strength in an ovariectomized rat model of osteoporosis. The results suggest that, in this experimental model, oil extract of garlic promotes intestinal transference of calcium by modulating the activities of both intestinal alkaline phosphatase and Ca(2+) activated ATPase. Also the observed low bone mineral content and low bone tensile strength in these rats were significantly restored by garlic oil supplementation. Further, garlic oil supplementation was able to revive partially the bilateral ovariectomy-induced decrease in the serum estrogen titer. The serum parathyroid hormone level, however, was found unaltered in these rats. The garlic oil supplemented partial recovery in serum estrogen titer in bilaterally ovariectomized rat was found to be persistently associated with enhanced calcium transference and better preservation of bone mineral content. The results of this study propose that the phytoestrogenic efficacy of an oil extract of garlic prevents ovarian hormone deficiency induced bone mineral loss possibly by promoting intestinal transference of calcium through the partial revival of the serum estrogen titer.

Combination of soy protein and high dietary calcium on bone biomechanics and bone mineral density in ovariectomized rats

OBJECTIVE

To determine if feeding soy in combination with a high-calcium diet would preserve bone mineral density and biomechanical bone strength to a greater extent than either soy or calcium alone.

DESIGN

Rats were sham-operated (n = l0) and fed a control diet (AIN93G containing 0.2% calcium, 20% casein) or ovariectomized (n = 40) and randomized to one of the following diets (n = 10 per group): control, high calcium (2.5% calcium, 20% casein), soy (0.2% calcium, 20% soy protein), or soy plus high calcium (2.5% calcium, 20% soy protein) for 8 weeks. Bone mineral density of femurs and lumbar vertebrae 1 through 6 were measured by dual energy x-ray absorptiometry. Biomechanical strength properties of femurs and the fifth lumbar vertebrae were measured by three-point bending and compression, respectively.

RESULTS

The dietary combination of soy and high calcium did not result in higher femur bone mineral density compared with other ovariectomized groups, and there were no differences in femur yield load or peak load among groups. In contrast, soy plus high calcium resulted in a higher (P < 0.05) vertebral bone mineral density compared with all other ovariectomized groups. Vertebral strength was preserved among rats fed either soy plus high calcium, soy, or high calcium whereas the ovariectomized group fed a control diet had lower (P < 0.05) vertebral strength than the sham-operated group.

CONCLUSION

Bone mineral density of the lumbar spine was the only bone outcome that significantly benefited from the combination of soy and high calcium compared with soy or high calcium alone.

Phytoestrogens and colorectal cancer prevention

Because colorectal cancer (CRC) is a leading cause of cancer mortality in the Western industrialized world, future chemopreventive strategies will be of high socioeconomic importance. Lower CRC incidences in Far Eastern countries in part may be attributed to high nutritional intake of soy and its abundance in phytoestrogens. Phytoestrogens are plant-derived substances which, due to molecular similarities to endogenous estrogens, distinctly interact with estrogen receptors ERalpha and ERbeta. Both genomic and nongenomic mechanisms have been shown to be responsible for possible anticarcinogenic properties of phytoestrogens, such as induction of apoptosis and inhibition of tyrosine kinases and DNA topoisomerases. This chapter provides a comprehensive review of a variety of studies exploring possible relations between phytoestrogen uptake and CRC risk. While in vitro and animal studies in general are somewhat supportive of a protective role of phytoestrogens against CRC, epidemiological work so far performed does not allow any conclusion on this issue. Studies about mechanisms of phytoestrogenic action against CRC development have been evaluated as well. Because estrogens, vitamin D, and calcium are frequently suggested to be important in CRC prevention, studies concentrating on interactions of phytoestrogens with these substances have been performed. Although support in evidence for a protective effect of phytoestrogens against CRC has increased over the last decade, it is still too early to give a definite recommendation, especially in view of enduring inconsistencies about concentrations most likely to be effective. Further experimental, and particularly epidemiological, studies are required to advance our understanding of the role of phytoestrogens against colon carcinogenesis.

The influence of estradiol and diet on small intestinal glucose transport in ovariectomized rats

Although gender differences exist for intestinal absorption of nutrients and drugs, the possible role estradiol may play in modulating nutrient transport has not been established. Therefore, small intestine glucose transport was measured 1 week after administering estradiol to ovariectomized rats fed diets high in carbohydrate (C) or protein (P). Rats treated with estradiol ate 21% less (P<0.05) and lost body mass (7%; P<0.05) but did not have smaller intestines. Administration of estradiol increased rates of glucose transport, but only when the rats were fed the C diet. These findings indicate that estradiol causes a disconnect between food intake and the dimensions and nutrient transport capacities of the small intestine. Furthermore, the responses to estradiol are influenced by diet composition, are not of the same magnitude for rats and dogs, and can be predicted to affect systemic availability of nutrients and drugs.

Lack of dose-responsive effect of dietary phyto-oestrogens on transepithelial calcium transport in human intestinal-like Caco-2 cells

Ca absorption has been shown to be unaffected by high luminal concentrations of two commonly consumed soyabean phyto-oestrogens (PO) (genistein and daidzein) in Caco-2 cells grown under oestrogen-depleted conditions. However, these compounds exhibit dose-dependent biphasic effects in some tissues, such as reproductive tissue and bone. Thus, in light of this biphasic activity, the effect of lower concentrations of genistein and daidzein on Ca absorption requires further investigation. Therefore, the aim of the present study was to investigate the effect of a range of concentrations of genistein and daidzein on Ca absorption in the human Caco-2 intestinal-like cell model. Caco-2 cells were seeded onto permeable filter supports and allowed to differentiate into monolayers. On day 21, the Caco-2 monolayers (n 12 per treatment), grown in oestrogen-deplete media, were then exposed to 10 nm-1,25-dihydroxycholecalciferol (1,25 (OH)2D3), or 1, 10 and 50 microm-genistein or -daidzein for 24 h. After exposure, transepithelial and transcellular transport of (45)Ca and fluorescein transport were measured. As expected, 1,25 (OH)2D3 stimulated Ca absorption in Caco-2 cells, by up regulating transcellular transport. Ca absorption was unaffected by either PO at luminal concentrations of 1, 10 or 50 microm, typical of intakes by Western and Asian populations as well as supplemental levels, respectively. The results of this model suggest that the proposed beneficial effects of supplemental levels of these PO compounds on bone mass in postmenopausal women more probably arise from direct effects on bone cells, and not by an indirect effect of these compounds on Ca absorption.

Soy isoflavones prevent the ovarian hormone deficiency-associated rise in leukocytes in rats

Recent reports indicate that ovariectomy (ovx) increases lymphopoiesis. Ipriflavone, a synthetic isoflavone, has been reported to reduce lymphocytes in postmenopausal women. The aim of this study was to investigate whether naturally occurring isoflavones also affect lymphopoiesis in ovarian hormone deficiency. The present study was carried out using an ovariectomized (ovx) rat model. To mimic early menopause, forty-eight 12-month-old Sprague-Dawley rats were either sham-operated (sham; 1 group) or ovx (3 groups) and were fed a standard semi-purified diet for 120 days. Thereafter, the ovx groups received one of the three doses of isoflavones: 0 (ovx), 500 (ISO500), or 1000 (ISO1000) mg/kg diet for 100 days. Ovariectomy increased total leukocyte counts significantly (p < 0.05) as a result of increased (p < 0.05) lymphocyte, monocyte, eosinophil, and basophil differential counts. Isoflavones at 500 and 1000 mg/kg diet returned the total leukocyte counts, as well as leukocyte subpopulations, to levels comparable to that of sham-operated rats. No other hematological parameters, e.g., red blood cell counts or red cell indices, were affected by ovariectomy or isoflavones. We conclude that soy isoflavones restore normal leukocyte counts elevated in ovarian hormone deficiency.

Calcium in Women: Healthy Bones and Much More

Osteoporosis is one of the leading health problems of women today, and the expectation is that more than 41 million women worldwide will be affected within the next 20 years if current trends are not reversed. Prevention of osteoporosis must be a focus for nurses, rather than merely the treatment of the problem. The majority of bone mass is developed during the adolescent and young adulthood years, with nearly 90% of skeletal mass accumulated by age 18. Current research has demonstrated that young women's intake of calcium is significantly below the recommended dietary intake. This article reviews the role and functions of calcium, how it is transported, and factors that may significantly increase or impair the absorption of this macronutrient. Strategies are described that will assist nurses in assessing the patient's diet and making appropriate recommendations regarding the intake of calcium and other micronutrients. A more in-depth and thorough understanding of this important mineral will enable nurses to strengthen their knowledge and confidence in helping patients and themselves change the focus from treating the disease to the improvement and maintenance of healthy bones and the prevention of other health conditions in women.

The effect of oestrogen and dietary phyto-oestrogens on transepithelial calcium transport in human intestinal-like Caco-2 cells

Recently, dietary phyto-oestrogens (PO) have been suggested as possible alternatives to oestrogen therapy (hormone replacement therapy) as a means of preventing bone loss associated with ovarian hormone deficiency. While PO, which exhibit oestrogen-like activity, act directly on bone cells, their protective effect on bone may be partly due to their ability to enhance Ca absorption. Therefore, the aim of the present study was to investigate the effect of 17beta-oestradiol and two commonly consumed soyabean PO (genistein and daidzein) on Ca absorption in the human Caco-2 intestinal-like cell model. Caco-2 cells were seeded onto permeable filter supports and allowed to differentiate into monolayers. On day 21, the Caco-2 monolayers (n 8-18 per treatment), grown in oestrogen-replete or -deplete media, were then exposed to 10 nm-17beta-oestradiol, 1 nm-1,25-dihydroxycholecalciferol, or 50 micro m-genistein or -daidzein for 24 h. After exposure, transepithelial and transcellular transport of 45Ca and fluorescein transport (a marker of paracellular diffusion) were measured. As expected, 1,25-dihydroxycholecalciferol stimulated Ca absorption in Caco-2 cells, by up-regulating transcellular transport, whereas 17beta-oestradiol had no effect on Ca absorption. Unexpectedly, both PO decreased Ca absorption (by about 17-19 % compared with control, P<0.05), by reducing transcellular Ca transport in Caco-2 cells grown in oestrogen-replete media. This inhibitory effect disappeared when monolayers were grown in oestrogen-deplete media. In conclusion, PO at high luminal concentrations either had no effect or reduced Ca absorption in Caco-2 cells, dependent on oestrogen status. The effect of lower concentrations of these compounds needs to be investigated.

Nutrient absorption

Many advances in the study of nutrient absorption have been made with the use of molecular and genetic techniques; however, standard in vivo studies have provided interesting and important new information. Omega-3 long-chain fatty acids have unexpected effects on lipoprotein formation and secretion in neonatal intestinal cells; this needs to be considered in the modification of infant formulas. Rexinoids affect intestinal cholesterol homeostasis via two receptors: retinoic acid receptor/liver X receptor (cholesterol efflux to lumen) and retinoic acid receptor/farnesoid X receptor (cholesterol catabolism). Absorption of the antioxidant plant polyphenol quercetin involves interaction with the glucose transporter and deglycolsylation and conjugation reactions. Cells of the polarized human colon cancer cell line, CaCo-2, take up phenylalanine by two mechanisms: passive uptake across the basolateral membrane, and temperature-dependent transcellular movement from apical to basolateral media. Absorption of vitamins A and E is markedly enhanced in normal and damaged intestine by the administration of restructured triacylglycerols derived from fish oil and medium-chain fatty acids. Surprisingly, dietary protein and phosphorus apparently have no significant effect on the efficiency of calcium absorption in adult women. Finally, many studies examined a variety of genes that regulate iron absorption and homeostasis.

Effects of vitamin K2 (menatetrenone) on calcium balance in ovariectomized rats

Vitamin K2 (menatetrenone) has been used for the treatment of osteoporosis in Japan. We investigated the effects of ovariectomy (OVX) and vitamin K2 on the calcium (Ca) balance in 20-week-old female Fischer rats. Vitamin K2 (31 mg/kg per day) was given to animals as a dietary supplement. At weeks 4 and 8 after OVX, a Ca balance study was performed for 5 days. The intestinal Ca transport was determined using the everted gut-sac technique at week 9. The Ca balance was poorer in the OVX-control group than in the sham-control group at weeks 4 and 8 after OVX. The Ca balance improved significantly in the vitamin K2 groups as compared with the sham- and OVX-control groups. The intestinal Ca transport decreased due to OVX and was higher in the vitamin K2 administration groups than in the sham- and OVX-control groups, but not to a significant extent. The bone mineral density in the femoral metaphysis as well as the cortical area and cortical thickness in the femoral diaphysis in the OVX-control group were lower than in the sham-control group. The administration of vitamin K2 significantly inhibited an OVX-induced decrease in cortical area and cortical thickness in the femur. These findings suggest that the poor Ca balance observed in ovariectomized rats may be improved by vitamin K2; vitamin K2 may be involved in preventing bone loss in vivo.