白藜芦醇对去卵巢大鼠骨密度的影响

目的:探讨白藜芦醇(RES)对去卵巢大鼠骨密度(BMD)的影响。方法:48只SD大鼠随机分为6组,分别接受假手术(A)、去卵巢(B)、去卵巢+0.03mg/(kgbw·d)己烯雌酚(DES,C)、去卵巢+RES5、15和45mg/(kgbw·d)(D,E,F)90d后,用双能X线吸收法测定大鼠的骨密度,观察其改变。结果:B组大鼠各BMD测定指标均显著低于A组,D、E、F组全身和腰椎BMD均显著高于B组,E、F组整体股骨BMD显著高于B组。结论:白藜芦醇对去卵巢大鼠的骨丢失有抑制作用,以45mg/(kgbw·d)剂量对骨密度的保护效果最好。     

Ovariectomy-induced hyperphagia does not modulate bone mineral density or bone strength in rats

The ovariectomized (OVX) rat is a widely used animal model for the development of prevention and treatment strategies for postmenopausal osteoporosis. However, ovariectomy-induced hyperphagia results in weight gain and adiposity. To prevent potential protective effects of increased body weight on bone from confounding outcomes of preclinical studies, pair-feeding is used in some but not all studies to control food intake, but its importance is not well elucidated. We investigated if the type of feeding, pair-feeding vs. consumption of diet ad libitum, modulates bone mineral and bone strength in OVX rats. Three-month-old female Sprague-Dawley rats (n = 12/group) were randomized to 1) sham-operated control (SHAM); 2) OVX pair-fed (OVX-PF); and 3) OVX ad libitum (OVX-AL). For 14 wk, OVX-PF rats were pair-fed with the SHAM group and daily food intakes and weekly body weights were obtained. At necropsy, regional body composition was measured by dual energy X-ray absorptiometry. Bone mineral density (BMD) and biomechanical bone strength of femurs and lumbar vertebrae (LV) were also measured. OVX-AL rats had higher overall food intake (P < 0.01), final body weight (P < 0.01), weight gain (P < 0.01), and fat mass (P < 0.05) than either SHAM and OVX-PF rats. Conversely, SHAM rats had higher femur (P < 0.001) and LV1-3 BMD (P < 0.001) as well as LV4 peak load (P < 0.01) than both the OVX groups, whereas bone outcomes did not differ between the OVX-PF and OVX-AL groups. In summary, ovariectomy-induced hyperphagia and weight gain do not modulate BMD or biomechanical strength at 14 wk postovariectomy, suggesting that pair-feeding is not essential.     

运动对去卵巢大鼠骨矿含量和骨密度的影响

目的观察运动对去卵巢大鼠骨矿含量（bone mineral contant,简称BMC）和骨密度（bone mineral den-sity,简称BMD）的影响。方法雌性（sprague daivley,简称SD）大鼠随机分为正常对照组（SHAM）、去卵巢手术对照组（OVX）、雌激素治疗组（OVX＋ES）、运动组（OVX＋ET）。SHAM组行假手术,其余各组行双侧卵巢切除术,术后75天开始为期3个月的治疗。OVX＋ES组用尼尔雌醇治疗,OVX＋ET组按要求进行运动。治疗结束后检测股骨和胫骨的BMC和BMD。结果股骨BMD比较,SHAM组（0．206±0．009）高于OVX组（0．196±0．012）,差异有统计学意义（P〈0．05）;胫骨BMC比较,OVX＋ET组（0．298士0．033）高于OVX组（0．260±0．033）,差异有统计学意义（P〈0．05）;胫骨BMD比较,0VX组比其它3组均低,差异有统计学意义（P〈0．05或P〈0．01）;运动明显提高去卵巢大鼠胫骨的BMC和BMD,运动在提高胫骨BMD方面的功效优干激素疗法．结诊运动对绝经后骨盾疏凇症的形成有一定干预作用。     

运动对去卵巢大鼠骨矿含量和骨密度的影响

目的观察运动对去卵巢大鼠骨矿含量(bone mineral contant,简称BMC)和骨密度(bonemineral density,简称BMD)的影响。方法雌性(sprague daivley,简称SD)大鼠随机分为正常对照组(SHAM)、去卵巢手术对照组(OVX)、雌激素治疗组(OVX+ES)、运动组(OVX+ET)。SHAM组行假手术,其余各组行双侧卵巢切除术,术后75天开始为期3个月的治疗。OVX+ES组用尼尔雌醇治疗,OVX+ET组按要求进行运动。治疗结束后检测股骨和胫骨的BMC和BMD。结果股骨BMD比较,SHAM组(0.206±0.009)高于OVX组(0.196±0.012),差异有统计学意义(P<0.05);胫骨BMC比较,OVX+ET组(0.298±0.033)高于OVX组(0.260±0.033),差异有统计学意义(P<0.05);胫骨BMD比较,OVX组比其它3组均低,差异有统计学意义(P<0.05或P<0.01);运动明显提高去卵巢大鼠胫骨的BMC和BMD,运动在提高胫骨BMD方面的功效优于激素疗法。结论运动对绝经后骨质疏松症的形成有一定干预作用。     

Low-exposure cadmium is more toxic on osteoporotic rat femoral bone: mechanical, biochemical, and histopathological evaluation

This study aimed to investigate the effects of low-exposure Cd on normal and osteoporotic bone. For this purpose, 12-week-old Sprague-Dawley female rats were assigned randomly to a control group, a Cd group, and an ovariectomy (OVX)+Cd group. OVX+Cd rats underwent bilateral ovariectomy via ventral incision. Twelve weeks after ovariectomy, cadmium chloride (CdCl(2)) was given to rats (Cd and OVX+Cd groups) as intraperitoneal (ip) injection of 0.5mg/kg three times a week for 18 weeks and distilled water was given to control group via ip route for 18 weeks. Bone mineral density (BMD) was measured at mid-diaphysis femoral region by dual-energy X-ray absorbsiometry. Cross-sectional area of the femoral shaft was evaluated by computerized tomography. Biomechanical measurements were performed at the mid-diaphysis of the left femur. Collagen fibers were evaluated at light microscopic level. BMD, cortical thickness, cortical area, and femur length were not changed in Cd and OVX+Cd groups in comparision to controls. In the OVX+Cd group, strength, displacement, energy, stress, strain, and toughness were significantly lower than those of the control group. The Cd concentration of bone was significantly increased in the OVX+Cd group compared to that in the control group. Collagen fiber intensity was decreased in all groups except control group. The results of the present study indicate that the administration of low-dose Cd does not affect normal bone biomechanical parameters, but it has a significant effect on osteoporotic bone.     

Flaxseed does not enhance the estrogenic effect of low-dose estrogen therapy on markers of uterine health in ovariectomized rats

Abstract Flaxseed (FS) is an oilseed rich in phytoestrogens and n-3 polyunsaturated fatty acids, compounds that may attenuate bone loss during aging. We previously demonstrated using the ovariectomized (OVX) rat model of postmenopausal osteoporosis that 10% dietary FS combined with low-dose estrogen therapy (LD) preserves vertebral bone mass and strength more so than either treatment alone. However, it was prudent to also consider the effect of this intervention on uterine tissue as LD, and possibly FS, may have estrogenic, and thus negative, effects on uterine tissue. The present study investigated if FS enhances the estrogenic effect of LD on markers of uterine health in OVX rats. Three-month-old rats were randomized to groups: (1) SHAM, (2) OVX, (3) OVX+FS, (4) OVX+LD, or (5) OVX+FS+LD. Ground FS was added to the AIN-93M diet (100?g/kg of diet), and LD was delivered by subcutaneous implant (0.42?μg of 17β-estradiol/kg of body weight/day) to mimic LD in postmenopausal women. After 12 weeks, histological analyses of uterine tissue demonstrated flattened or cuboidal luminal epithelia organized in a single layer in the OVX group, while FS, LD, and FS+LD induced a single layer of elongated luminal epithelia, columnar in shape. The SHAM group had the greatest epithelial mass. Cell proliferation was similar among all OVX groups. Therefore FS and FS+LD similarly induce estrogen-like effects on the morphology of luminal epithelia that are weaker than in the SHAM group without inducing cell proliferation in OVX rats. Thus, FS does not enhance the estrogenic effect of LD on markers of uterine health in OVX rats.     

椒目油改善铁过载雌性去势大鼠骨质疏松的作用研究

目的 椒目油（Zanthoxylum bungeanum Maxim seed oil, ZBSO）对铁过载雌性去势SD大鼠骨质疏松的保护作用及机制初探。方法 将40只雌性SD大鼠随机分为假手术组（SHAM）、去势组（OVX）、铁过载组（Fe）、铁过载+椒目油组（Fe+ZBSO）。除SHAM组外，其余各组均实施卵巢切除术，Fe、Fe+ZBSO组以100 mg/kg·bw/w腹腔注射右旋糖酐铁，此外Fe+ZBSO组以3.46 ml/kg·bw/d干预12周。干预结束后，取股骨Micro-CT扫描骨结构和骨密度；ELISA法测定血清Ⅰ型胶原交联羧基端肽（CTX Ⅰ）、Ⅰ型前胶原氨基端原肽（PⅠNP）、8-羟基脱氧鸟苷（8-OHdG）、3-硝基酪氨酸（3-NT）的含量；比色法测定血清丙二醛（MDA）的浓度。结果 Fe、Fe+ZBSO组相较于OVX组，血清铁蛋白含量上升（q=19.230,q=10.050,P＜0.001）；相较于SHAM组，OVX（Z=3.977,P＜0.001）、Fe（Z=4.542,P＜0.001）、Fe+ZBSO（Z=3.241,P=0.004）组子宫脏器指数降低。相较于Fe组，Fe+ZBSO组股骨结构更完整，骨密度上升（t=6.222,P＜0.001）；骨代谢结果显示，Fe+ZBSO组CTX Ⅰ降低（t=2.603,P=0.019）、PⅠNP升高（t=2.839,P=0.012）；氧化损伤标志物结果显示，Fe+ZBSO组3-NT降低（t=2.894,P=0.015）、MDA降低（t=4.456,P＜0.001），8-OHdG无差异（F=0.101,P=0.959）。结论 椒目油能改善铁过载去势雌性SD大鼠的股骨骨骺端结构，提高骨密度，调节骨代谢，这可能是通过降低氧化损伤实现的。     

雌激素干预对去卵巢大鼠骨组织的影响

目的:建立绝经后骨质疏松(PMO)模型,外源性补充雌激素,探讨雌二醇(E_2)的骨保护作用及其对胞质活化T细胞核因子1(NFATc1)表达的影响。方法:12周龄Wistar雌性大鼠随机分为假手术组(Sham组)、去势组(OVX组)、实验组(OVX+E_2组),每组10只。OVX+E__2组给予17β-E_2皮下注射,其余2组给予等量生理盐水。16周后,酶联免疫吸附试验(ELISA)测定血清E_2水平,逆转录聚合酶链反应(RT-PCR)法测定骨组织中NFATc1表达量,微型计算机断层成像(Micro-CT)分析大鼠胫骨平台处骨密度(BMD)、骨体积分数(BV/TV)、骨小梁厚度(Tb.Th)、骨小梁数目(Tb.N)。结果:Sham组、OVX+E_2组与OVX组相比,BMD、Tb.Th、Tb.N、BV/TV、血清E_2水平升高,NFATc1水平下降(均P0.05)。结论:雌激素可能通过抑制NFATc1的表达减缓骨量丢失。     

Short- and long-term effects of calcium and exercise on bone mineral density in ovariectomized rats

At the level of prevention of bone mineral loss produced by ovariectomy, the aim of the present study was to determine the effect produced by supplementation of Ca in the diet and a moderate exercise programme (treadmill), simultaneously or separately, in ovariectomized rats, an experimental model of postmenopausal bone loss. Female Wistar rats (n 110, 15 weeks old) were divided into five groups: (1) OVX, rats ovariectomized at 15 weeks of age, fed a standard diet; (2) SHAM, rats sham operated at 15 weeks of age, fed a standard diet; (3) OVX-EX, ovariectomized rats, fed a standard diet and performing the established exercise programme; (4) OVX-Ca, ovariectomized rats fed a diet supplemented with Ca; (5) OVX-EXCa, ovariectomized rats with the exercise programme and diet supplemented with Ca. The different treatments were initiated 1 week after ovariectomy and were continued for 13 weeks for subgroup 1 and 28 weeks for subgroup 2, to look at the interaction of age and time passed from ovariectomy on the treatments. Bone mineral density (BMD) was determined, at the end of the study, in the lumbar spine (L2, L3 and L4) and in the left femur using a densitometer. Bone turnover was also estimated at the end of the study, measuring the serum formation marker total alkaline phosphatase (AP) and the resorption marker serum tartrate-resistant acid phosphatase (TRAP). As expected, OVX rats showed a significant decrease (P<0.05) in BMD, more pronounced in subgroup 2, and a significant increase in AP and TRAP with regard to their respective SHAM group. The simultaneous treatment with Ca and exercise produced the best effects on lumbar and femoral BMD of ovariectomized rats, partially avoiding bone loss produced by ovariectomy, although it was not able to fully maintain BMD levels of intact animals. This combined treatment produced a significant increase in AP, both in subgroups 1 and 2, and a decrease in TRAP in subgroup 1, with regard to OVX group. The exercise treatment alone was able to produce an increase in BMD with regard to OVX group only in subgroup 1 of rats (younger animals and less time from ovariectomy), but not in subgroup 2. In agreement with this, there was an increase of AP in both subgroups, lower than that observed in animals submitted to exercise plus Ca supplement, and a decrease of TRAP in subgroup 1, without significant changes in this marker in the older rats. Ca treatment did not produce any significant effect on BMD in OVX rats in both subgroups of animals, showing a decrease of AP and TRAP levels in the younger animals with no significant variations in markers of bone remodelling in the older female rats compared with their respective OVX group.     

Dose-dependent bone-sparing effects of dietary isoflavones in the ovariectomised rat

The dose-dependent bone-sparing effects of dietary isoflavones (IF) were investigated in adult (7-month-old) Wistar rats. Forty animals were ovariectomised, allocated into four groups of ten rats each, and immediately treated orally with IF at 0 (OVX), 20 (IF20), 40 (IF40) or 80 (IF80) microg/g body weight per d for 91 d; ten sham-operated (SH) controls received the same diet without added IF. Animals were killed on day 91. Both femoral failure load and total femoral, diaphyseal or metaphyseal bone mineral densities (BMD) were lower in OVX animals than in SH animals. Urinary deoxypyridinoline (DPD) excretion, a marker of bone resorption, and plasma osteocalcin (OC) levels, a marker of osteoblast activity, were higher in OVX animals than in SH animals. Total femoral and diaphyseal BMD and femoral failure load were similar in IF-treated rats and SH rats. Although metaphyseal BMD in IF40 or IF80 rats was similar to that in SH rats, its value was lower in IF20 rats than in controls. The day 91 urinary DPD excretion in IF40 and IF80 rats, but not in IF20 rats, was similar to that in SH rats. Day 91 plasma OC concentrations in IF-treated rats were similar to day 45 values, but were decreased in OVX and SH rats. Thus, daily IF consumption prevented ovariectomy-induced bone loss, both by depressing bone resorption and stimulating osteoblast activity. Moreover, as only the highest IF level induced a weak uterotrophic activity, the optimal IF dose which preserves both cancellous and cortical bone, but exhibits no oestrogen-like effects on the uterus, was 40 microg/g body weight per d.     

硫酸软骨素加钙对卵巢切除大鼠骨密度和骨钙含量的影响

目的探讨硫酸软骨素加钙对卵巢切除大鼠模型骨密度和骨钙含量的影响。方法选用卵巢切除大鼠所诱发的骨质疏松模型，给予硫酸软骨素加钙治疗，同时设假手术组及模型对照组。3个月后测定大鼠骨密度、骨钙含量。结果发现假手术组和高剂量组大鼠股骨骨密度和股骨钙含量显著高于阴性对照组（P〈0．05）。结论表明硫酸软骨素加钙能增加卵巢切除大鼠的骨密度，对雌激素缺乏所诱发的骨钙丢失具有抑制作用。     

Resveratrol attenuates ovariectomy-induced hypertension and bone loss in stroke-prone spontaneously hypertensive rats

We examined the effect of resveratrol (3,4',5-trihydroxy stilbene), a phenolic compound found in the skins of most grapes, on blood pressure and bone loss in ovariectomized (OVX), stroke-prone spontaneously hypertensive rats (SHRSP). Nineteen-week-old female SHRSP were divided into a sham-ovariectomized (sham) group fed a control diet and two OVX groups fed either a control diet (OVX-Cont) or a diet supplemented with resveratrol (5 mg/kg per d; OVX-Resv). Ovariectomy induced significant increases in systolic blood pressure (SBP). Resveratrol lowered the SBP by 15%) by the third week of administration, and this effect was maintained throughout the study. Resveratrol treatment also significantly enhanced endothelium-dependent vascular relaxation in response to acetylcholine (ACh) in OVX rats. Finally, femur breaking energies measured for the resveratrol-treated (OVX-Resv) group were significantly higher than those of the resveratrol-untreated (OVX-Cont) group. While no significant differences in calcium, magnesium and phosphorus content were found between the femurs of OVX-Cont and OVX-Resv rats, the femur hydroxyproline content in the OVX-Resv group was significantly higher than of the OVX-Cont group. We conclude that, in OVX-SHRSP, resveratrol acts by a similar mechanism to mammalian estrogens, lowering blood pressure by increasing dilatory responses to ACh. The present study also demonstrated that resveratrol was able to prevent ovariectomy-induced decreases in femoral bone strength.     

Hesperidin,a citrus flavonoid,inhibits bone loss and decreases serum and hepatic lipids in ovariectomized mice

The purpose of this study was to examine whether hesperidin inhibits bone loss in ovariectomized mice (OVX), an animal model of postmenopausal osteoporosis. Forty 8-wk-old female ddY mice were assigned to five groups: a sham-operated group fed the control diet (AIN-93G), an OVX group fed the control diet, an OVX+HesA group fed the control diet containing 0.5 g/100 g hesperidin, and an OVX+HesB group fed the control diet containing 0.7 g/100 g alpha-glucosylhesperidin and an OVX+17beta-estradiol (E(2)) group fed the control diet and administered 0.03 micro g E(2)/d with a mini-osmotic pump. After 4 wk, the mice were killed and blood, femoral, uterine and liver were sampled immediately. Hesperidin administration did not affect the uterine weight. In OVX mice, the bone mineral density of the femur was lower than in the sham group (P < 0.05) and this bone loss was significantly prevented by dietary hesperidin or alpha-glucosylhesperidin. The Ca, P and Zn concentrations in the femur were significantly higher in the hesperidin-fed and E(2) groups than in the OVX group. Histomorphometric analyses showed that the trabecular bone volume and trabecular thickness in the femoral distal metaphysis were markedly decreased (P < 0.05) by OVX, and alpha-glucosylhesperidin significantly prevented this bone loss. Furthermore, hesperidin decreased the osteoclast number of the femoral metaphysis in OVX mice, as did E(2). Serum and hepatic lipids were lower in mice that consumed the hesperidin-containing diets (P < 0.05) than in the OVX group fed the control diet. These results suggest a possible role for citrus flavonoids in the prevention of lifestyle-related diseases because of their beneficial effects on bone and lipids.     

玛咖独行菜对卵巢切除术后大鼠血脂及骨质代谢的影响

目的利用雌激素低下动物模型,探讨玛咖独行菜(LepidiummeyemiiWalp,俗称Maca)对雌性大鼠体脂、性激素、骨代谢的影响。方法健康SD雌性大鼠进行卵巢切除术后根据体重随机分为模型组、雌激素组以及Maca低、中、高剂量组;另设未做卵巢切除术的假手术组作为对照组。雌激素组每天灌胃己烯雌酚(30μg/kgbw);Maca低、中、高剂量组每天分别灌胃Maca悬浊液0.3、0.6、1.8g/kg;假手术组和模型组每天灌胃蒸馏水。7周后测定各组大鼠体重、子宫和肾上腺重量,及血脂、性激素、骨代谢相关指标的水平。结果模型组显示卵巢切除术后大鼠体重快速增长,子宫、肾上腺重量降低,雌、孕激素及睾酮水平下降,血脂水平增高,血碱性磷酸酶水平升高(和假手术组相比,P<0.05)。相比之下,给予己烯雌酚的雌激素组血雌激素水平提高、子宫重量维持不变、体重过度增长得到改善(和模型组相比,P<0.05);Maca高剂量组大鼠的低密度脂蛋白胆固醇、甘油三酯和血碱性磷酸酶水平明显降低,骨钙素的作用增强(和模型组相比,P<0.05),但性激素分泌无显著变化。结论玛咖独行菜有助于改善卵巢切除术后血脂异常和骨质代谢。     

橄榄油对大鼠去势后骨代谢指标及骨密度的影响

目的:观察橄榄油对去势后大鼠骨代谢和骨密度的影响,探讨并分析橄榄油防治绝经后骨质疏松症(PMOP)的有效性及机理。方法:将30只5～6个月龄清洁型SD雌性大鼠进行随机分成四组:①假手术组(Sham组)、②去卵巢组(OVX组)、③去卵巢+橄榄油组(OVX+Olive)、④去卵巢+雌激素组(OVX+E)。治疗组用药:(OVX+Olive)组及(OVX+E)组均采用经口灌胃方式进行用药,按1 ml/100 g体重,1次/天灌胃,连续12周。12周后分别左心室取血,检测血中雌二醇(E2)、血钙、血碱性磷酸酶(ALP)、白介素-6(IL-6)水平,放血处死后取出腰椎及左侧股骨行双能X线骨密度(DEXA)测定。结果:OVX组中血E2明显低于Sham组和治疗组,差异有统计学意义(P<0.01、P<0.05),ALP、IL-6值显著高于其余三组,差异有统计学意义(P<0.05);治疗组中E2、ALP、IL-6与Sham组差异无统计学意义(P>0.05);四组中血钙值差异均无统计学意义(P>0.05)。去势橄榄油组与雌激素组骨密度平均值均较OVX组高,差异有统计学意义(P<0.05),但该两组间差异无统计学意义(P>0.05)。结论:橄榄油能有效地减轻大鼠卵巢切除术引起的骨质丢失,可能通过补充植物雌激素发挥拟雌激素样作用。     

Effects of taurine supplementation on bone mineral density in ovariectomized rats fed calcium deficient diet

Taurine supplementation has been shown to have a beneficial effect on femur bone mineral content in ovariectomized rats. It therefore seemed desirable to find out whether the beneficial effect of taurine on ovariectomized rats fed calcium deficient diet could also be reproduced. Forty female Sprague-Dawley rats were divided into two groups. One group was OVX and the other group received sham operation (SHAM), and received either control diet or a taurine supplemented diet for 6 weeks. All rats were fed on calcium deficient diet (AIN-93: 50% level of calcium) and deionized water. Bone mineral density (BMD) and bone mineral content (BMC) were measured in spine and femur. The serum and urine concentrations of calcium and phosphorus were determined. Bone formation was measured by serum osteocalcin and alkaline phosphatase (ALP) concentrations. Bone resorption rate was measured by deoxypyridinoline (DPD) crosslinks immunoassay and corrected for creatinine. Urinary calcium and phosphorus excretion, osteocalcin in blood and cross link value were not significantly different among the groups. Within the OVX group, the taurine supplemented group had not higher femur bone mineral content than the control group. This study established the need for a study on the taurine effect on bone with different calcium levels.     

Effects of daidzein and kiwifruit on bone mineral density and equol production in ovariectomised rats

In this study, we investigated the synergistic effects of daidzein (Dz) and kiwifruit on bone and equol production in ovariectomised (OVX) rats. Female Sprague-Dawley rats were randomly assigned to one of five groups: sham operated, OVX control, OVX fed 0.1% Dz-supplemented diet (OVX?+?Dz), OVX fed 0.1% Dz and green kiwifruit (GRK)-supplemented diet (OVX?+?Dz?+?GRK) and OVX fed 0.1% Dz and gold kiwifruit (GOK)-supplemented diet (OVX?+?Dz?+?GOK). There were no significant differences in whole body and femur bone mineral density (BMD) among groups at week 8. BMD in the OVX group significantly decreased at week 8; however, BMD in the OVX?+?Dz?+?GRK was not significantly different from baseline in the end of the study. However, supplementation with kiwifruit did not affect urinary equol concentrations, urinary ratios of equol to Dz and the composition of caecal microbiota. These results suggest that the combination of Dz and GRK may slightly reduce bone loss caused by oestrogen deficiency but does not affect equol production.     

Daidzein is more efficient than genistein in preventing ovariectomy-induced bone loss in rats

We investigated the ability of genistein and daidzein, two soybean isoflavones, compared with that of 17 alpha-ethinylestradiol, to prevent bone loss in ovariectomized rats, a model for postmenopausal osteoporosis. Female Wistar rats (n = 65; 12 mo old) were either sham-operated (SH; n = 13) or ovariectomized (OVX; n = 52). On d 0, OVX rats were randomly assigned to groups as follows: 13 received genistein [G; 10 mcg/(g body weight. d)], 13 were treated with daidzein [D; 10 mcg/(g body weight. d)], 13 received 17 alpha-ethinylestradiol [E(2); 30 mcg/kg body weight. d)] and 13 were untreated (OVX). Compounds were mixed with a soy protein-free powdered semipurified diet and given orally for 3 mo. On d 90, the bone mineral density (BMD) in lumbar vertebrae, femur and its metaphyseal and diaphyseal zones (rich in cancellous and cortical bone, respectively) was lower in OVX than in SH (P < 0.01). In D or E(2), the four BMD were not different from SH, whereas in G, only the diaphyseal BMD was not different from SH. Image analysis performed in the distal femur metaphysis revealed that the cancellous bone area was lower in OVX than in SH (P < 0.01). Only the area in D was not different from that in SH. Finally, the bone turnover, which was higher in OVX than in SH (P < 0.005 and P < 0.05 for plasma osteocalcin concentration and urinary deoxypyridinoline excretion, respectively), was not different in G, D or E(2) compared with SH. Therefore, consumption of 17 alpha-ethinylestradiol or daidzein was more efficient than genistein in preventing ovariectomy-induced bone loss in rats.     

Equol, a metabolite of daidzein, inhibits bone loss in ovariectomized mice

Soybean isoflavones have structures similar to that of estrogen and have received attention as alternatives to hormone replacement therapy for the prevention of postmenopausal osteoporosis. Daidzein, a major isoflavone found in soybean, is metabolized to equol by gut microflora, and the metabolite exhibits a stronger estrogenic activity than daidzein. However, there is no direct evidence that equol affects bone metabolism. In this study, we examined the effect of equol on the inhibition of bone loss in ovariectomized (OVX) mice. Female mice (8 wk old) were assigned to 5 groups as follows: sham-operated (sham), OVX, OVX + 0.1 mg/d equol administration (0.1 Eq), OVX + 0.5 mg/d equol administration (0.5 Eq), and OVX + 0.03 microg/d 17beta-estradiol administration (E(2)). Equol and E(2) were administered s.c., using a mini-osmotic pump. At 4 wk after the intervention, uterine weight was less in the OVX mice than in sham-operated mice (P < 0.05). The weight was maintained in the E(2) group. In contrast, administration of equol at doses used in this study did not affect uterine atrophy in OVX mice. Bone mineral density (BMD) for the whole body in the OVX group measured by dual-energy X-ray absorptiometry was lower than that in the sham group, whereas administration of 0.5 mg/d Eq as well as E(2) maintained the BMD. The BMD of the femur and lumbar spine in the OVX group was also lower than those in the sham group, and treatment with 0.5 mg/d Eq maintained it. Notably, the BMD of the proximal femur in the 0.5 Eq group was the same as that of the sham group. E(2) inhibited bone loss from all regions induced by OVX. These results suggest that equol, a major metabolite of daidzein, inhibits bone loss apparently without estrogenic activity in the reproductive organs of OVX mice.     

Genistein may prevent cadmium-induced bone loss in ovariectomized rats

This study compared the ability of genistein, a soy isoflavone, with that of 17 beta-estradiol to prevent bone loss in cadmium (Cd)-exposed ovariectomized (OVX) rats during growth. Female Wistar rats (4 weeks old) were either sham-operated (SH; n = 9/group) or OVX and placed on experimental diets (n = 9/group): OVX; OVX rats fed 50 ppm of CdCl(2) (OVX-Cd); OVX fed 50 ppm of CdCl(2) and 10 microg/kg of body weight genistein (OVX-Cd-G); and OVX fed 50 ppm of CdCl(2) and 10 microg/kg of body weight estrogen (OVX-Cd-E). All rats were given free access to AIN-76 modified diet and drinking water, with or without Cd, for 8 weeks. The OVX groups gained more body weight than the SH group. Femoral weight was increased by feeding genistein and estradiol, whereas femoral length among groups was not significantly different. Femoral Cd content was significantly higher in the OVX-Cd group than in the other groups. Both serum osteocalcin and calcium (Ca) concentrations, as well as urinary Ca, were significantly higher in the OVX-Cd group than in the other groups. Urinary excretion of Cd was significantly increased in Cd-OVX-G rats, and fecal Cd excretion was increased by feeding both genistein and estradiol. Femoral histomorpological changes in proliferative cartilage and hypertrophic cells in the OVX-Cd group showed that both cell types were decreased by feeding Cd, and irregular arrangements were observed in proliferative cells. However, both cells types exhibited normal distribution in OVX-Cd-G and OVX-Cd-E groups. These findings suggest that Cd/OVXinduced osteopenia or osteoporosis probably results from an increase in bone turnover. Genistein may be involved in stimulating Cd excretion and inhibiting Ca excretion from bone.