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.     

Comparison of chemical,histomorphometric, and absorptiometric analyses of bones of growing rats subjected to dietary calcium stress.

Absorptiometric, histomorphometric, and chemical analyses of bones from growing rats fed diets with low (0.2%, w/w), marginal (0.4%, w/w), or adequate (0.8%, w/w) calcium (Ca) content with or without phytate were compared. Phytate was added to each diet in a molar ratio of 19:1 to calcium. Male weanling Sprague-Dawley rats were fed one of the six diets for 8 weeks. At the end of 8 weeks, rats were killed, and mandibles, femurs, and tibias were removed. Bone density profiles were determined on the mandibles and femurs using single photon absorptiometry. Femurs were also used for calcium and phosphorus analyses. Tibias were used for histomorphometric analyses. Bone density of the femurs and mandibles increased as dietary Ca increased. The only effect of phytate addition measured was in the 0.8% calcium diet, where density was lower in rats fed the phytate-containing 0.8% calcium diet. Femur calcium concentration also increased as dietary Ca increased and was unaffected by addition of phytate. Femur phosphorus concentration was unaffected by dietary Ca levels but was increased by 10% when phytate was added to the diet. Bone density values were highly correlated with bone calcium and phosphorus levels (r = 0.94). Rats fed the 0.2% calcium diets had 20% lower mineralized bone area and 20% larger medullary cavity area than rats fed the other diets. Bone densitometry appears to be useful for determining changes in bone occurring in growing rats fed low, marginal, and adequate levels of dietary Ca. Bone density values also correlated well with chemically determined calcium and phosphorus concentrations and with histomorphometric data.     

大豆异黄酮对去势大鼠骨量丢失的抑制作用研究

目的:研究大豆异黄酮(Soybeanisoflavone,SI)对去势后大鼠由于体内雌激素水平下降引起的骨量丢失的抑制作用。方法:腹腔手术切除大鼠双侧卵巢,分为对照组、SI组和雌激素对照组,并设假手术对照组,喂养16w后,测定雌二醇、骨生化指标、骨密度、骨钙、骨磷等指标,扫描电镜和组化分析观察骨小梁微观结构的变化。结果:SI显著降低血清中骨吸收指标TRAP活性,同时明显提高骨形成指标BGP含量;SI具有弱雌激素作用,可抑制去卵巢大鼠体内雌激素水平的下降,骨密度和骨钙、骨磷含量增加,松质骨的骨丢失得到抑制。结论:SI可降低骨吸收、促进骨形成,对去卵巢引起的骨量丢失有明显的抑制作用。     

补钙对大鼠峰值骨量形成和预防骨质疏松的作用

目的 :　探讨补钙对峰值骨量的影响及对绝经后骨质疏松发生的预防作用。方法 :　选用雌性大鼠喂给不同钙含量的饲料至 1 0 mo龄 ,半数动物断头处死 ,取股骨进行相关检测 ,了解不同钙摄入量对骨峰值的影响。半数动物行卵巢切除术 ,喂饲 1 0 w后断头处死 ,取股骨进行有关检测 ,了解不同峰值骨量对骨质疏松的预防作用。结果 :　高钙摄入组峰值期大鼠股骨骨密度、骨重、骨长度、骨皮质厚度和股骨最大载荷、骨应变量等值均较低钙摄入组高 ;去卵巢后各组骨密度均降低 ,但高钙摄入量大鼠股骨骨密度比低钙摄入量大鼠的高。结论 :　钙摄入量的增加能有效提高峰值骨量 ,较高的峰值骨量能延缓骨质疏松的发生和降低骨折发生的危险性     

Fructooligosaccharide consumption enhances femoral bone volume and mineral concentrations in rats

We examined whether the enhanced mineral absorption resulting from fructooligosaccharide (FOS) consumption affects femoral bone structure and mineral concentrations, using histomorphometrical and X-ray microanalysis. Male Wistar rats (n = 16; 42 d old) were divided into two groups, a control group (n = 8) and a FOS group (5 g/100 g FOS in the diet, n = 8). After a 3-d adaptation period, constant amounts of calcium (95 mg/d) and magnesium (8 mg/d) were fed to the rats in each group, using a pair-feeding protocol. At age 60 d, a 3-d metabolic study was initiated. Calcium and magnesium absorptions were calculated. The rats were then killed, and the right femur was embedded in polyester resin. The distal metaphysis was sagittal-sectioned, and the middle of the diaphysis and neck were cross-sectioned. Calcium, magnesium and phosphorus concentrations in the three samples were then measured. Calcium and magnesium absorptions were significantly greater in FOS-fed rats. Trabecular bone volume at the metaphysis and bone volume at the neck of the femur in FOS-fed rats were also significantly greater than those in control rats. The mineral concentration (Ca, Mg and P) in each region of the bone surface was greater in FOS-fed rats. There was a significant relationship between absorbed calcium and calcium concentrations in bone (r = 0.722, P < 0.001), and a similar relationship was found for magnesium (r = 0.720, P < 0.001). These results suggest that the enhanced calcium and magnesium absorption due to FOS consumption might enhance femoral bone volume and mineral concentrations.     

Nondigestible oligosaccharides increase calcium absorption and suppress bone resorption in ovariectomized rats

Nondigestible oligosaccharides (NDO) including inulin and fructooligosaccharides (FOS) have been reported to stimulate calcium absorption. Here we report the effect of a mixture of inulin and FOS (Raftilose Synergy 1, Orafti) on calcium and bone metabolism in ovariectomized (OVX) rats. OVX rats (6 mo old) were fed a semipurified diet for 3 mo in our animal care laboratory for stabilization after ovariectomy. They were then divided into two groups (n = 13/group) and fed either a control or a NDO-supplemented diet (55 g/kg) for 21 d. Catheters were placed in their jugular veins. After 2 d, a tracer ((45)Ca) was administered by gavage or i.v. and blood was sampled for up to 300 min. Urine and fecal samples were collected for 4 d after (45)Ca administration. Femurs were measured for bone mineral density (BMD), breaking strength, and total calcium. Calcium absorption, femoral calcium content, BMD, and bone balance (V(bal)) were significantly increased (P < 0.05) by NDO, whereas the bone resorption rate relative to the bone formation rate was significantly depressed by NDO. We conclude that feeding NDO at 5.5 g/100 g for 21 d has a positive effect on calcium absorption and retention in ovariectomized rats.     

大豆异黄酮和钙对去卵巢大鼠骨密度及微量元素的影响

目的 :探讨大豆异黄酮和钙对去卵巢大鼠的骨密度及微量元素的影响。方法 :2 8只雌性SD大鼠随机分为假手术组、去卵巢组、去卵巢补钙组 [5 0mg/ (kg·d) ]和去卵巢加大豆异黄酮组 [大豆异黄酮 10 0mg/ (kg·d) ],10周后测骨密度和骨矿物含量及血清、尿液和骨骼钙、锌、铜、铁含量。结果 :实验结束后 ,去卵巢后大鼠的骨密度和骨矿物含量、骨骼钙、锌、铜、铁和血清锌、铁显著下降 ,血清钙、铜、ALP及尿钙、铜、铁显著性增高(P <0 0 1和P <0 0 5 ) ;与单纯去卵巢组比 ,大豆异黄酮组大鼠的骨密度、骨矿物含量、血清锌 ,骨骼中钙、锌、铜显著升高 ,血清钙、铜、ALP及尿钙、铜显著性下降 (P <0 .0 1和P <0 .0 5 ) ,而补钙组各指标都无显著性意义。结论 :大豆异黄酮可预防去卵巢大鼠骨钙、锌、铜丢失 ,预防骨质疏松。     

Comparison of chemical, histomorphometric, and absorptiometric analyses of bones of growing rats subjected to dietary calcium stress

Absorptiometric, histomorphometric, and chemical analyses of bones from growing rats fed diets with low (0.2%, w/w), marginal (0.4%, w/w), or adequate (0.8%, w/w) calcium (Ca) content with or without phytate were compared. Phytate was added to each diet in a molar ratio of 19:1 to calcium. Male weanling Sprague-Dawley rats were fed one of the six diets for 8 weeks. At the end of 8 weeks, rats were killed, and mandibles, femurs, and tibias were removed. Bone density profiles were determined on the mandibles and femurs using single photon absorptiometry. Femurs were also used for calcium and phosphorus analyses. Tibias were used for histomorphometric analyses. Bone density of the femurs and mandibles increased as dietary Ca increased. The only effect of phytate addition measured was in the 0.8% calcium diet, where density was lower in rats fed the phytate-containing 0.8% calcium diet. Femur calcium concentration also increased as dietary Ca increased and was unaffected by addition of phytate. Femur phosphorus concentration was unaffected by dietary Ca levels but was increased by 10% when phytate was added to the diet. Bone density values were highly correlated with bone calcium and phosphorus levels (r = 0.94). Rats fed the 0.2% calcium diets had 20% lower mineralized bone area and 20% larger medullary cavity area than rats fed the other diets. Bone densitometry appears to be useful for determining changes in bone occurring in growing rats fed low, marginal, and adequate levels of dietary Ca. Bone density values also correlated well with chemically determined calcium and phosphorus concentrations and with histomorphometric data.     

去势雌鼠骨质疏松模型研究

本文采用骨形态计量学、扫描电镜—能谱分析(SEM-EDXA)等方法综合评价成年去势大鼠骨丢失情况。结果显示:OVX组与sham组比较,胫骨小梁体积明显降低.小梁显著变窄,类骨质体积增加,骨形成和骨吸收均增强,但吸收大于形成;胫骨SEM-EDXA检测Ca、P元素x线光子数分别降低50%;肱骨湿重、干重、灰重与体重之比明显下降,骨钙含量显著减少;血清磷明显升高、AKP升高16.2%,血清雌二醇含量显著降低等。以上多种方法检测结果均证实,4月龄SD大鼠切除卵巢后10周,由于雌激素缺乏,造成了典型的绝经后骨质硫松动物模型,可广泛用作抗骨质疏松药物的体内筛选。     

山茶籽油对绝经后骨质疏松症治疗作用的实验研究

目的:观察山茶籽油对去卵巢大鼠骨组织和骨代谢的影响,为山茶籽油防治绝经后骨质疏松症提供实验依据。方法:6月龄健康雌性SPF级SD大鼠80只,分成4个实验组(每组20只):①对照组、②去卵巢组、③去卵巢+己烯雌酚组(DTS)、④去卵巢+山茶籽油组(CSO)。治疗组用药:去卵巢+己烯雌酚组,皮下注射己烯雌酚,治疗剂量为300 ug/kg,2次/周,连续12周;去卵巢+山茶籽油组,采用经口灌胃方式进行用药(山茶籽油),治疗剂量为5 ml/kg,每天1次,连续12周。各实验组在第12周,麻醉大鼠后取左心血,用于测量血清雌二醇、黄体酮、促卵泡激素、黄体生成素及血清钙、磷和碱性磷酸酶;再将大鼠处死后,取股骨近端切片观察骨组织结构。数据进行统计学分析。结果:与对照组比较,去卵巢组的血清钙、磷和雌二醇明显降低(P﹤0.01),而血清碱性磷酸酶、促卵泡激素明显升高(P﹤0.01),骨组织切片呈骨质疏松的病理改变;与去卵巢组比较,2个治疗组的血清钙、磷和雌二醇明显升高(P﹤0.01),而血清碱性磷酸酶、促卵泡激素明显降低(P﹤0.01),骨组织切片骨质疏松的病理改变得到明显改善。结论:山茶籽油对去卵巢大鼠的骨质疏松症有治疗作用,与己烯雌酚治疗效果相近。     

The effect of spiny lobster shell powder on bone metabolism in ovariectomized osteoporotic model rats.

Calcium has been found to be indispensable in the prevention of osteoporosis. Recently, there has been a great deal of research into the best way to consume calcium. In this study, the effect of "powdered lobster shell" on bone metabolism was examined in ovariectomized osteoporotic model rats. This powder has a good flavor and taste, and contains high quantities of calcium. Six-week-old SD-strain female rats were ovariectomized and were fed a low Ca diet (0.01% Ca and 0.3% P) for 32 days. Thereafter, the rats were divided into two groups; the control group was fed a control diet (0.3% Ca and 0.3% P) and an experimental group, the lobster group, was fed a lobster shell powder diet (0.3% Ca and 0.3% P) ad libitum for 30 days. The results were as follows: in comparison with the control group, the lobster group had significant increases in (1) bone mineral density [BMD (DEXA Hologic's QDR-1000] of lumbar spines and tibial proximal metaphyses, which are mainly trabecular bones, and BMD of tibial diaphyses, which is a mainly cortical bone, (2) the breaking force and energy of femur. These results suggests the lobster shell powder could be a valuable source of dietary calcium in increasing BMD, breaking force and energy in osteoporotic model rats.     

牛乳碱性蛋白对正常和去卵巢大鼠骨代谢的影响

目的探讨牛乳碱性蛋白(MBP)对正常大鼠和去卵巢大鼠骨代谢的影响。方法将60只去除卵巢雌性SD大鼠随机分为假手术、去卵巢对照以及去卵巢低、中、高剂量5组;将另外44只正常雌性SD大鼠随机分为正常对照、正常低、中、高剂量4组。分别采用10、20、30mg/kgbwMBP给大鼠连续灌胃90d,检测股骨近心端、中段和远心端骨密度,同时检测股骨中Ca、Mg、P等矿物元素含量。结果正常低剂量组大鼠股骨远心端骨密度显著高于正常对照组;而各剂量MBP对去卵巢大鼠的骨密度无显著作用;正常各组之间以及去卵巢组之间比较,骨矿物质含量虽无统计学差异,但可以观察到其水平上的上升趋势。结论10mg/kg.bw的MBP能提高正常生理状态下的峰值骨密度,以股骨远心端效果最好,但未见MBP对去卵巢大鼠骨密度的影响。MBP除影响骨骼中矿物元素含量外,还可能通过其他方式作用于骨代谢。     

Dietary magnesium supplementation affects bone metabolism and dynamic strength of bone in ovariectomized rats

We evaluated the effect of magnesium supplementation on apparent calcium absorption, bone metabolism and dynamic bone strength in ovariectomized (OVX) rats as a model of postmenopausal women. Two groups of OVX rats were fed a 0.05% Mg diet or a 0.15% Mg diet, and one group of sham-operated rats was fed the 0.05% Mg diet for 42 d. We collected feces and urine of all rats for 3-d periods starting from d 3, 10, 17, 24, 31 and 38 of the feeding experiment for calcium and magnesium balance studies. Urine was collected for 24 h from d 41 of the feeding experiment for measuring deoxypyridinoline. After the 42 d, the rats were killed, serum prepared and femora excised. The apparent calcium absorption in the OVX rats fed 0.15% Mg was significantly lower than both other groups. Additionally, the urinary excretion of deoxypyridinoline (a bone resorption marker) and the serum parathyroid hormone level of the OVX rats fed the 0.15% Mg diet were significantly lower than in the OVX rats fed 0.05% Mg. Serum osteocalcin (a bone formation marker) in the OVX rats fed the 0.15% Mg diet was significantly higher than in the OVX rats fed 0.05% Mg. The breaking force and breaking energy of the femur in the OVX rats fed the 0.15% Mg diet were significantly higher than in the OVX rats fed the 0.05% Mg diet. These results indicate that magnesium supplementation reduces apparent calcium absorption, but promotes bone formation and prevents bone resorption in OVX rats. Moreover, our results indicate magnesium supplementation increases the dynamic strength of bone.     

Effect of dietary legumes on bone-specific gene expression in ovariectomized rats

In previous studies, we found that the consumption of legumes decreased bone turnover in ovariectomized rats. The purpose of the present study is to determine whether the protective effects on bone mineral density (BMD) and the microarchitecture of a diet containing legumes are comparable. In addition, we aim to determine their protective actions in bones by studying bone specific gene expression. Forty-two Sprague-Dawley rats are being divided into six groups during the 12 week study: 1) rats that underwent sham operations (Sham), 2) ovariectomized rats fed an AIN-93M diet (OVX), 3) ovariectomized rats fed an AIN-93M diet with soybeans (OVX-S), 4) ovariectomized rats fed an AIN-93M diet with mung beans (OVX-M), 5) ovariectomized rats fed an AIN-93M diet with cowpeas (OVX-C), and 6) ovariectomized rats fed an AIN-93M diet with azuki beans (OVX-A). Consumption of legumes significantly increased BMD of the spine and femur and bone volume of the femur compared to the OVX. Serum calcium and phosphate ratio, osteocalcin, expression of osteoprotegerin (OPG), and the receptor activator of nuclear factor κB ligand (RANKL) ratio increased significantly, while urinary excretion of calcium and deoxypyridinoline and expression of TNF-α and IL-6 were significantly reduced in OVX rats fed legumes, compared to OVX rats that were not fed legumes. This study demonstrates that consumption of legumes has a beneficial effect on bone through modulation of OPG and RANKL expression in ovariectomized rats and that legume consumption can help compensate for an estrogen-deficiency by preventing bone loss induced by ovarian hormone deficiency.     

大豆异黄酮类对去卵巢大鼠骨丢失的影响

目的　研究大豆中植物雌激素——异黄酮类对去卵巢大鼠骨丢失的预防作用。方法　将 3月龄 SD雌性大鼠按体重分为 5组 ,每组 1 1只 :假手术对照组 (假手术 +饲含酪蛋白饲料 ,Sham) ;去异黄酮组 (去卵巢 +饲含去异黄酮类大豆分离蛋白饲料 ,Soy- ) ;异黄酮组 (去卵巢 +饲含异黄酮类大豆分离蛋白饲料 ,Soy+) ;酪蛋白组 (去卵巢 +饲含酪蛋白饲料 ,即去卵巢对照组 ,Ovx) ;雌激素对照组 (去卵巢 +饲含酪蛋白饲料 +注射雌二醇 ,E2 )。在实验期第 3周、第 6期和第 9周各进行为期三天的钙代谢试验。第 1 0周末处死大鼠 ,测定骨钙、骨密度 ,并对股骨远端松质骨进行骨组织形态学测量。结果　异黄酮组和雌激素对照组粪钙、尿钙排出量显著低于酪蛋白组和去异黄酮组 (P<0 .0 5) ,钙表观吸收率和钙贮留量显著高于酪蛋白组和去黄酮组 (P<0 .0 5) ,钙代谢呈正平衡。异黄酮组和雌激素对照组骨钙、骨密度高于酪蛋白组和去异黄酮组 (P<0 .0 5)。与雌激素对照组比较 ,异黄酮组骨小梁面积百分率和骨小梁数目明显减少 ,骨小梁间隙明显增宽 (P<0 .0 5) ;但与酪蛋白组和去异黄酮组比较 ,异黄酮组骨小梁面积百分率和骨小梁数目明显增多 ,骨小梁间隙明显减少 (P<0 .0 5)。结论　含有异黄酮类的大豆分离蛋白具有预防骨丢失的作用 ,而?     

蛇床子总香豆素对去卵巢大鼠骨质疏松症大鼠骨矿和骨微量元素的影响

目的研究蛇床子总香豆素（TCFC）对去卵巢大鼠骨质疏松症骨组织骨矿和微量元素含量的影响。方法切除大鼠双侧卵巢制作骨质疏松症动物模型，测定动物骨组织中Ca、P、Zn、Cu、Fe、Mg等元素含量。结果模型组大鼠骨组织中的Ca、P、Zn、Cu、Fe、Mg的含量显著降低，蛇床子总香豆素各组可明显增加去卵巢大鼠骨组织中微量元素的含量。结论蛇床子总香豆素对雌激素缺乏引起的骨矿和微量元素丢失具有明显的防治作用。     

Grapefruit juice modulates bone quality in rats

Hypogonadism and oxidative stress increase the risk for developing osteoporosis. The objective of this research was to evaluate the efficacy of drinking grapefruit juice on bone quality in orchidectomized (ORX) and non-ORX rats. Fifty-six 90-day-old male Sprague-Dawley rats were equally divided into four groups--non-ORX rats (sham), sham + grapefruit juice, ORX, and ORX + grapefruit juice--and treated for 60 days. Thereafter, all rats were sacrificed to determine the plasma antioxidant status, insulin-like growth factor I (IGF-I), and indices of bone turnover, bone quality, and calcium and magnesium concentrations in the bone, urine, and feces. Orchidectomy decreased (P < .05) antioxidant status, bone quality, and bone mineral contents and increased (P < .05) indices of bone turnover, urinary deoxypridinoline, calcium, and magnesium, and fecal calcium excretions. In contrast to the ORX group, ORX rats that drank grapefruit juice had an increase (P < .05) in antioxidant status, bone density, and bone mineral contents, delayed femoral fracture, and slowed down (P < .05) bone turnover rate and tended to have a decrease (P = .08) in urinary deoxypridinoline. In sham-treated animals, drinking grapefruit juice increased (P < .05) bone density and tended to increase the femoral strength. The concentration of IGF-I in the plasma was not affected across treatments. In conclusion, drinking grapefruit juice positively affected bone quality by enhancing bone mineral deposition in ORX rats and by improving bone density in non-ORX rats via an undefined mechanism.     

Dietary chicory inulin increases whole-body bone mineral density in growing male rats

Chicory inulin is a natural linear fructan that is not digested in the upper part of the gastrointestinal tract but is fermented in the cecocolon. It enhances calcium absorption in rats and improves femur and tibia mineral contents in gastrectomized or ovariectomized rats. We studied the effect of inulin (0, 5 and 10 g/100 g diet) on whole-body bone mineral content (WBBMC), whole-body bone area (WBBA) and whole-body bone mineral density (WBBMD) in live, growing male rats fed diets containing 0.2, 0.5 or 1 g Ca/100 g. Three experiments, each corresponding to one of the different dietary Ca concentrations, were performed using male Wistar rats (n = 108; 4 wk old). WBBMC was measured by dual-energy X-ray absorptiometry every 4 wk up to wk 22. Inulin increased WBBMC (P < 0.05) and WBBMD (P < 0.001) significantly but not WBBA at all ages and all dietary calcium concentrations. This is the first report to demonstrate that chicory inulin not only increases calcium absorption but also increases mineral parameters in whole-body bones.     

女性系统性红斑狼疮患者骨密度与骨代谢生化参数的相关性

目的 测定绝经前女性系统性红斑狼疮患者骨密度(BMD)与骨代谢的生化参数并探讨二者的相关性。方法 用双能量X线吸收测量仪测定30例SLE患者腰椎和股骨BMD；常规测定分别测定30例SLE患者和39名正常健康者校正后的血清钙、磷、碱性磷酸酶、肌酐和白蛋白，用ELISA法测定卵泡促激素、黄体生成素、甲状旁腺素、骨钙素、脱氧吡诺林的分泌，用RIA法测定雌二醇、孕酮、睾丸酮、25-OH维生素D、I型原胶原C端前肽、碱性磷酸酶骨特异性同工酶、交联的I型胶原端肽。结果 根据世界卫生组织的标准，在腰椎位点39％患者BMD正常，46％患者骨质减少，15％患者骨质疏松；在股骨颈位点，38．5％患者BMD正常，38．5％患者骨质减少，23％患者骨质疏松。狼疮患者骨钙素、血清磷显著性降低(P=0．03、P=0．002)，而患者校正后的血清钙则显著性升高(P=O．0001)；除了患者睾丸酮的血清水平降低和卵泡促激素血清水平升高外(P=0.001、P=0．42)，其它性激素水平没有显著性差异。结论 绝经前女性SLE患者腰椎和股骨颈的骨质疏松和骨质减少发生率高，至少部分因骨形成的减少所致。     

Prolonged magnesium deficiency causes osteoporosis in the rat

BACKGROUND: Peroral magnesium (Mg) administration, used as the only treatment in postmenopausal osteoporosis, has been shown to cause a significant increase of BD. OBJECTIVES: To gauge the role of magnesium deficiency in the etiology of osteoporosis, we compared rats fed a Mg deficient diet daily with rats fed a Mg adequate diet over a period of one year. METHODS: Sprague-Dawley female rats (mean weight 110, SD 23 g) were divided into two groups of 8 and randomly assigned to an identical semisynthetic diet, containing either 2000 ppm (group A) or 200 ppm Mg (group B). Urine samples were collected every 3 months and blood samples at end of trial. After sacrifice, L3-L5 vertebrae and the femoral regions were examined for bone density (BD) using dual energy X-ray absorptiometry. The femurs were examined for bone fragility, the tibias by histomorphometry and the mineral contents of the bones was estimated. RESULTS: The mean BD of L3-L5 vertebral bone (BDL) was significantly higher in group than in the Mg deficient group B (p = 0.035, 1 tail). The BD of the femoral region (BDF) was also significantly higher in group A (p = 0.045, 1 tail). The stiffness of the femur, as determined by resistance to bending, was slightly greater in group A than in group B, but after correction to diminish the influence of the difference in bone dimensions in the two groups, the stiffness (ie loss of elasticity) in group B became significantly greater than that in group A (p = 0.024). The force needed to break the bone (F-max) was significantly higher in group A, than in group B (p = 0.024) and remained so after correction, although no longer significantly. In Group B, the diminution of the trabecular bone volume, in relation to tissue volume (BV/TV) and the increase in the degree of trabecular interconnection (TBPf) indicated osteoporosis, and focal osteoporosis of the metaphyseal spongy bone was seen on microscopy. CONCLUSION: Experimentally induced prolonged Mg deficiency causes osteoporosis in rats.