Risedronate improves bone architecture and strength faster than alendronate in ovariectomized rats on a low-calcium diet

Clinical evidence suggests that, compared with alendronate, risedronate reduces fracture risk faster and more potently, with less bone mass gain. We tested the hypothesis that risedronate improves bone quality faster than alendronate using calcium-deficient, ovariectomized (OVX) rats. Female Sprague–Dawley rats at 24 weeks of age were divided into sham-operated and OVX groups and fed a low-calcium (0.05 %) diet under paired feeding. After 12 weeks, OVX rats were divided into five groups and treated with vehicle, risedronate (3.5 and 17.5 μg/kg/week, s.c.) or alendronate (7 and 35 μg/kg/week, s.c.). Rats were killed 6–8 weeks later and the bone architecture and strength of the left femur were evaluated by micro-computed tomography and a three-point bending test. Trabecular bone mineral density (BMD), number and thickness were significantly lower in OVX rats than in the sham-operated group. Cortical BMD, bone area (Ct.Ar), and thickness (Ct.Th) were similarly decreased. Risedronate significantly improved Ct.Ar (+8 %) and Ct.Th (+9 %) at 6 weeks, while alendronate only caused a significant improvement in Ct.Ar (+8 % at 6 weeks) and only at the higher dose. At 8 weeks, both risedronate and alendronate significantly increased trabecular BMD compared with the vehicle. Bone strength parameters showed a significant correlation between Ct.Ar and Ct.Th. Risedronate significantly improved maximum load at 6 weeks, while alendronate failed to produce any significant changes. Our results suggest that risedronate is superior to alendronate at improving cortical bone architecture and strength, and that enhanced bone quality partly accounts for risedronate’s efficacy.     

Individual and combined effects of exercise and alendronate on bone mass and strength in ovariectomized rats

Exercise and bisphosphonate therapies increase bone strength by primarily increasing bone formation and reducing resorption, respectively. Based on these different mechanisms of action, it is possible that combined introduction of exercise and bisphosphonate therapies generates greater improvements in bone mass and strength than either intervention alone. The aim of this study was to examine the individual and combined effects of exercise (treadmill running) and bisphosphonate therapy (alendronate [ALN]) on bone mass and strength in ovariectomized (OVX) rats. Seven-month-old virgin female rats were randomly assigned to either a sham-OVX group (n=13) or one of four OVX groups: vehicle-treated cage-control (VEH-CON, n=10); ALN-treated cage-control (ALN-CON, n=13); vehicle-treated plus treadmill running (VEH-RUN, n=13); and ALN-treated plus treadmill running (ALN-RUN, n=13). ALN-treated groups received twice-weekly ALN (0.015 mg/kg), and exercise groups ran on a motorized treadmill at a 5% incline for 60 min/day, 22-24 m/min, 5 days/week. In vivo measurements included dual-energy X-ray absorptiometry (DXA) of whole-body bone mineral content (BMC), and ex vivo measurements included DXA, micro-computed tomography (muCT), and mechanical testing of the femur and L4 vertebrae. After 14 weeks of intervention, exercise and ALN had additive benefits on whole body and proximal femur BMC, cross-sectional area of the L4 vertebrae, and mechanical properties of the mid-shaft femur. In comparison, for total and mid-shaft femur BMC, L4 vertebrae BMC, and mid-shaft femur cortical thickness and area, there were significant exercise and ALN interactions indicating that the two interventions worked in synergy to enhance bone properties. Supporting the contention that ALN and exercise function via distinct mechanisms of action, ALN successfully reduced medullary canal area suggesting it reduced endocortical bone resorption, whereas exercise augmented periosteal perimeter suggesting it stimulated periosteal bone formation. In summary, we found combined treadmill running and ALN to be more beneficial in preventing declines in bone mass and strength following OVX than the introduction of either intervention alone. These data suggest that a comprehensive program of bisphosphonate therapy and weight-bearing exercise may be an effective method for preventing and treating osteoporosis in post-menopausal women.     

替勃龙对去势大鼠骨强度的影响研究

目的探讨替勃龙对切除卵巢大鼠骨强度的影响。方法选用6月龄未交配健康雌性Sprague-Dawley大鼠共40只,随机分为4组(每组10只)①正常对照组或假手术组(Sham),②空白对照组即骨质疏松组(OVX),③OVX加戊酸雌二醇(ValerateEstriolVE)组(0.8mg/kg),④OVX加替勃龙(Tibolone)组(0.25mg/kg);行去势手术3周后开始按分组设计喂药(灌胃),共治疗3个月后处死。取大鼠右股骨及第3腰椎进行骨密度测定;之后对右股骨标本进行中段三点弯曲试验,测定股骨干强度指标;取大鼠第4、5腰椎制作不脱钙病理切片后进行图像分析计量。统计学处理P<0.05为具有统计学意义。结果①骨密度椎骨及股骨干骺端骨密度OVX组明显下降,使用戊酸雌二醇能够提升骨密度;但股骨干骨密度各组间差异无显著性。②骨强度三点弯曲实验结果显示OVX组股骨干强度较假手术组明显下降,替勃龙组骨干强度较OVX组提升30%(P<0.05)。③椎骨形态计量结果OVX组与假手术组、戊酸雌二醇组及替勃龙组间差异均有显著性。结论短期小剂量替勃龙治疗能阻止卵巢切除导致的成熟雌性大鼠股骨干强度受损。     

Parathyroid hormone monotherapy and cotherapy with antiresorptive agents restore vertebral bone mass and strength in aged ovariectomized rats

Previous studies have shown that parathyroid hormone (PTH) monotherapy and cotherapy with estrogen or risedronate augment vertebral bone mass and bone strength in young, ovariectomized (OVX) rats. The current study was designed to determine whether PTH has similar bone anabolic effects in aged OVX rats at a much later stage of estrogen depletion. Female Sprague Dawley rats were subjected to sham surgery or bilateral ovariectomy at three months of age and maintained untreated for one year after surgery to allow for the development of vertebral osteopenia in OVX rats. Groups of baseline control and OVX rats were sacrificed at the end of this pretreatment period. The remaining OVX rats were then treated for ten weeks with vehicle, antiresorptive agents alone (estrogen, risedronate, or calcitonin), or PTH alone. Other groups of OVX rats were treated concurrently with PTH and each of the antiresorptive agents. The first and fourth lumbar vertebral bodies were processed undecalcified for quantitative bone histomorphometry and biomechanical testing, respectively. As expected, bone mass and compressive strength were decreased in the lumbar vertebral body of baseline OVX rats compared to baseline control rats. This bone loss was associated with decreases in trabecular number and width and an increase in trabecular separation. Treatment with estrogen, risedronate, or calcitonin alone failed to reverse the changes in bone mass, structure, and strength induced by ovariectomy. In contrast, treatment of OVX rats with PTH alone restored vertebral cancellous bone volume and ash density to the level of vehicle-treated control rats and increased vertebral maximum load, stress, and normalized load to well above this level. The hormone significantly increased trabecular width, but not number, in the lumbar vertebral body of OVX rats. Concurrent treatments with PTH and the antiresorptive agents did not augment cancellous bone and biomechanical competence to a greater, or lesser, extent than treatment with PTH alone. Compressive strength correlated significantly with bone mass and trabecular width in the lumbar vertebral body. These results indicate that PTH completely restores lost bone mass and improves bone strength in the vertebral body of aged OVX rats with established osteopenia. With our previous study in younger OVX rats, the current study demonstrates that the anabolic effect of PTH is independent of age and the stage of estrogen depletion in the rat skeleton.     

Effects of two non-endurance exercise protocols on established bone loss in ovariectomized adult rats

Summary The effects of non-endurance exercise on bone properties were evaluated in 9-month-old sham-operated (SH) and ovariectomized (OVX) rats. The studies were started 3 months postsurgery, after bone mass was decreased in OVX rats. The sham and OVX rats were either kept sedentary (SED) or were trained to run with one of two protocols: 12 m/minute, 50 minutes/day, 4 days/week (low intensity, frequent, EX-1); or 21 m/minute, 40 minutes/day, 1 day/week (moderate intensity, infrequent, EX-2). A group of seven rats evaluated at the beginning of the study served as baseline control. The bone mineral was assessed by the ash weight of the left femur, tibia, and 4th lumbar vertebra. Biomechanical (strength, deformation, stress, strain, and stiffness) and morphometric (length, cortical and medullary area, moment of inertia) properties were evaluated for the right femur. There was a significantly lower bone mineral and mechanical properties in OVX-SED (n=7) than in SH-SED (n=10) rats. The OVX-EX-1 (n=6) rats had higher ash content of femur and tibia than OVX-SED rats, but the change was significant only for tibia. The EX-2 had no effect on the ash content, but femur stress was higher in OVX-EX-2 (n=8) than in OVX-SED rats. The femur yield force and deformation were improved in OVX rats with both exercise protocols, whereas the vertebra ash weight, femur strain, modulus of elasticity, length, cortical area, and moment of inertia were not changed. Non-endurance exercise did not affect bone properties in either SH-EX-1 (n=7) or SH-EX-2 (n=8) groups. We conclude that non-endurance exercise has beneficial effects on established osteopenia in ovariectomized rats.     

Effects of risedronate on femoral bone mineral density and bone strength in sciatic neurectomized young rats

Immobilization induces a rapid loss of bone density and bone strength in rats. The purpose of the present study was to examine the effects of risedronate (Ris) on the femoral bone density and bone strength of sciatic neurectomized young rats. Forty male Sprague–Dawley rats, 6 weeks of age, were randomized by the stratified weight method into the following four treatment groups of 10 rats each: sham-operation, bilateral sciatic neurectomy (NX), NX + low-dose Ris (0.25 mg/kg/day, orally), and NX + high-dose Ris (0.5 mg/kg/day, orally). After 8 weeks of feeding, the volumetric bone mineral density (vBMD) and stress strain index (SSI) of the femoral distal metaphysis and middiaphysis of the rats were measured by peripheral quantitative computed tomography. The mechanical properties of the femoral distal metaphysis and middiaphysis were measured by the compression and three-point bending tests, respectively. The femoral length was also measured. As compared with the findings in the sham-operated controls, NX resulted in a loss of femoral length, cancellous vBMD, SSI, maximum load, stiffness, and breaking energy of the femoral distal metaphysis; there was also loss of cortical thickness, SSI, maximum load, and stiffness of the femoral middiaphysis, with no significant effects on the cortical vBMD or breaking energy of the femoral middiaphysis. High-dose Ris increased the vBMD to values higher than those in the sham-operated controls, and prevented the loss of SSI, maximum load, and stiffness of the femoral distal metaphysis, while low-dose Ris prevented the loss of cancellous vBMD of the femoral distal metaphysis. Neither high- nor low-dose Ris affected any of the cortical bone parameters of the femoral middiaphysis, except for cortical thickness, or the femoral length. These findings suggest that Ris may prevent immobilization-induced loss of cancellous bone density and bone strength in a dose-dependent manner without interfering with bone growth, but has no apparent effects on the cortical bone in sciatic neurectomized young rats. The results of the present preclinical study should be taken into consideration prior to the commencement of Ris treatment for disabled children.     

Effects of 5-year treatment with elcatonin and alfacalcidol on lumbar bone mineral density and the incidence of vertebral fractures in postmenopausal women with osteoporosis: a retrospective study

 The purpose of this retrospective study was to compare the effects of long-term treatment (5 years) with elcatonin and alfacalcidol on bone mineral density (BMD) and the incidence of vertebral fractures in postmenopausal women with osteoporosis. Fifty-six osteoporotic women, more than 5 years after menopause and 58–79 years of age, were enrolled in the study and allocated to an elcatonin treatment group (20 units IM, weekly; n = 30) or an alfacalcidol treatment group (1 μg/day, daily; n = 26). BMD of the lumbar spine (L2-L4) was measured by dual energy X-ray absorptiometry at baseline and every year for 5 years. There were no significant differences in age, body mass index, years since menopause, BMD, or number of prevalent vertebral fractures at baseline between the two groups. One-way analysis of variance with repeated measurements showed no significant longitudinal changes in BMD in either group, suggesting that both treatments sustained the BMD over 5 years. Two-way analysis of variance with repeated measurements also showed no significant differences in longitudinal changes in BMD between the two groups, suggesting that the effects of the two treatments on BMD were similar. However, the number of incident vertebral fractures per patient was significantly lower in the alfacalcidol treatment group than in the elcatonin treatment group (0.80 ± 1.19 and 2.08 ± 2.73, respectively; P < 0.05). These findings indicate that both treatments appeared to sustain lumbar BMD similarly over a 5-year period in postmenopausal women with osteoporosis, but alfacalcidol treatment may be superior to elcatonin treatment regarding the incidence of vertebral fractures. Further study with prospective observations are needed to confirm the results of the present study. Received: April 2, 2002 / Accepted: July 13, 2002 Offprint requests to: J. Iwamoto     

Effects of h-PTH on cancellous bone mass, connectivity, and bone strength in ovariectomized rats with and without sciatic-neurectomy.

The purpose of this study was to determine whether h-PTH (1-34) treatment would recover cancellous bone connectivity and bone strength in ovariectomized (OVX) or ovariectomized and sciatic-neurectomized (OVX+NX) rats. Seven-month-old female Wistar rats were treated with h-PTH or vehicle (6.0 microg/kg, six times a week, subcutaneously) for four weeks beginning 4, 8, or 12 weeks after OVX or OVX+NX. These were compared to age-matched baseline and sham-operated groups. Right tibiae were used for bone histomorphometry and node-strut analysis, and left tibiae were used for mechanical testing. The bone formation rates in the OVX and OVX+NX rats treated with h-PTH were significantly higher than those in their baseline controls. h-PTH treatment increased the node numbers and failure energies in the OVX rats, compared to their baseline controls, at all time points. However, in the OVX+NX rats, the effects of h-PTH treatment on the node number and failure energy were observed only at four weeks after surgery, but not at eight weeks or 12 weeks after surgery. These results suggest that the lowest limit, at which trabecular connectivity and bone strength are able to be restored by h-PTH, occurred between four and eight weeks in OVX+NX rats, but not in OVX rats. h-PTH cannot recover trabecular connectivity and bone strength in advanced osteopenia.     

Effects of combined treatment with eldecalcitol and alendronate on bone mass,mechanical properties,and bone histomorphometry in ovariectomized rats: A comparison with alfacalcidol and alendronate

Eldecalcitol (ELD), a 2β-hydroxypropyloxy derivative of 1α,25 (OH) 2D3, inhibits bone resorption more potently than alfacalcidol (ALF) while maintaining osteoblastic function in an ovariectomized (OVX) osteoporosis rat model. Alendronate (ALN), which is the most common bisphosphonate used for the treatment of osteoporosis, increases the bone mineral density (BMD) by suppressing bone resorption. In this study, we investigated the effects of combination treatments with ELD and ALN or with ALF and ALN on bone mass and strength in OVX rats. Seventy female rats, 32 weeks old, were assigned to seven groups: (1) a sham-operated control group; (2) an OVX-control group; (3) an ELD group; (4) an ALF group; (5) an ALN group; (6) an ELD + ALN group; and (7) an ALF + ALN group. OVX rats were orally treated with ELD (0.015 μg/kg), ALF (0.0375 μg/kg), or ALN (0.2 mg/kg) daily for 12 weeks. In both the lumbar spine and the femur, ELD and ALF monotherapy significantly increased the BMD, and ELD + ALN and ALF + ALN significantly increased the BMD, compared with ALN monotherapy, as an additive effect. In particular, ELD + ALN resulted in a significantly higher BMD than ALF + ALN in the femur. On mechanical testing of the lumbar spine, ELD and ALF monotherapy significantly increased the ultimate load, and ELD + ALN and ALF + ALN significantly increased the ultimate load compared with ALN monotherapy. In the femur, ELD, ELD + ALN, and ALF + ALN treatment significantly increased the ultimate load, compared with the OVX-control group, and ELD + ALN resulted in a significantly higher ultimate load than ALN monotherapy. A histomorphometric analysis showed that ELD monotherapy and ELD + ALN combination therapy had a potent inhibitory effect on bone resorption parameters (osteoclast surface and eroded surface), while maintaining bone formation parameters (osteoblast surface and osteoid surface). By contrast, ALF and ALF + ALN significantly lowered the histological parameters of both bone resorption and formation. These results suggested that ELD or ALF used in combination with ALN has therapeutic advantages over ALN monotherapy, with ELD + ALN combination treatment producing an especially beneficial anti-osteoporotic effect by inhibiting osteoclastic bone resorption and maintaining osteoblastic function, compared with ALF + ALN combination treatment.     

辛伐他汀联合阿仑膦酸钠对去卵巢骨质疏松大鼠骨代谢的影响

目的探讨辛伐他汀联合阿仑膦酸钠干预对去卵巢大鼠骨质疏松骨代谢的影响。方法 60只雌性SD大鼠随机平均分为5组:假手术组、去势组、辛伐他汀组、阿仑膦酸钠组、联合药物组,首先构建去卵巢大鼠骨质疏松性模型。分别检测骨代谢相关生化指标、氧化应激生化指标和骨组织骨密度(bone mineral density,BMD),HE染色观察骨组织形态学。结果去势组大鼠血清Ca、P、SOD、CAT和骨组织BMD均较假手术组显著降低(P0.05),辛伐他汀组、阿仑膦酸钠组、联合药物组上述指标均较去势组升高,以联合用药组升高最显著(P0.05)。去势组大鼠血清ALP、BGP、PICP、TRAP、GLA、ICIP和MDA较假手术组均显著增高(P0.05),辛伐他汀组、阿仑膦酸钠组、联合药物组上述指标较去势组均降低,以联合用药组降低最显著(P0.05)。去势组股骨骨小梁明显稀疏,连接不完整,大量纤维组织,髓腔内大量空泡状脂肪细胞。联合药物组骨小梁数目明显增多,结构较完整,粗细均匀致密,连接成网状。结论辛伐他汀联合阿仑膦酸钠通过调节去卵巢大鼠骨代谢,抗氧化应激,增加骨密度,改善骨组织结构,发挥抗骨质疏松作用。     

Effects of nicotine on bone mass and strength in aged female rats.

This study investigated the effects of nicotine on bone mass and biomechanical properties in aged, estrogen-replete (sham-operated) and estrogen-deplete (ovariectomized) female rats. Eight month old, retired breeder, sham-operated and ovariectomized Sprague-Dawley rats were left untreated for 12 weeks to establish cancellous osteopenia in the ovariectomized group. The animals were then administered saline, low dose nicotine (6.0 mg/kg/day) or high dose nicotine (9.0 mg/kg/day) via osmotic minipumps for 12 weeks. Vertebrae and femora were collected at necropsy for determination of bone mass and strength. As expected, ovariectomy had a negative effect on most endpoints evaluated. Vertebral body bone mineral content (BMC) and density (BMD) and the structural (ultimate load and yield load) and material (ultimate stress, yield stress, and flexural modulus of elasticity) strength properties were lower in the OVX rats than in the sham-operated rats. Femoral diaphysis BMC, BMD, ultimate load, and flexural modulus were also lower in the OVX rats than in the sham-operated rats. The nicotine doses administered resulted in serum nicotine levels that averaged 1.5-4.5-fold greater than those observed in heavy smokers. Despite the high doses used, nicotine had no effect on vertebral BMC, BMD, or any of the structural and material strength properties in either the OVX or the Sham rats. In addition, nicotine had no effect on femoral diaphysis BMC, BMD, ultimate load, stiffness, ultimate stress, or flexural modulus. Femoral yield load and stress were lower in low dose nicotine-treated rats than in vehicle-treated rats. However, differences were not detected between the high dose nicotine- and vehicle-treated rats for either femoral yield load or stress. The results suggest that tobacco agents other than nicotine are responsible for the decreased bone density and increased fracture risk as observed in smokers.     

中西医结合治疗对去卵巢大鼠骨生物力学的影响

目的探讨中西医结合治疗对去卵巢大鼠骨生物力学的影响。方法70只3月龄未交配的雌性SD大鼠腹腔手术切除双侧卵巢,按体重随机分为去卵巢组、17α-炔雌醇组、益坤口服液中剂量组、益坤口服液大剂量组2、益坤小剂量 戊酸雌二醇组、益坤小剂量 17α-炔雌醇组,并设假手术组对照。喂养12周后,分离大鼠股骨,三点弯曲实验法测定最大载荷、最大桡度、弹性载荷、弹性桡度及弹性能量吸收,分析天平称骨量。结果大鼠去卵巢后股骨结构力学特性指标均显著下降,各用药组与OVX组相比均有显著上升,其中中西医结合治疗组更加显著(P<0.01)。结论中西医结合治疗可改善去卵巢大鼠骨的生物力学性能,降低其发生骨折的危险性。     

Effects of drug treatment on bone strength and structural changes with aging: an experimental study in rats

 The purpose of the present study was to evaluate the profiles of the bone strength of rats treated from infancy with various drugs. Young female Sprague-Dawley rats were classified into five groups according to the composition of their diets. They underwent resection of their femurs for a three-point flexion test and an impaction test at 6, 8, 12, and 16 months of age. A microcomputed tomography unit was used to evaluate the microstructure of their femoral condyles at 16 months of age. The diet given to the rats in the control group contained 0.5% Ca. The rats in groups A, B, C, and D were placed on the following regimens, respectively: vitamin K mixed diet, vitamin D oral administration, 1.8% Ca-fortified diet, and 1.8% Ca-fortified diet plus vitamin K and vitamin D. In the impaction tests conducted on the rats at each age, the results from groups A and B were nearly the same as those from the control group. At 16 months of age, the rats in groups C and D had significantly higher test results than those in the control group. In the three-point flexion tests at 16 months of age, the results from groups A, B, and C were nearly the same as those from the control group. The results from group D, however, showed a significant increase. Examination of the microstructure of the femoral condyles at 16 months of age revealed controlled destruction of the trabecular structure in groups C and D. These findings suggest that supplementing the diet from infancy with Ca, vitamin K, and vitamin D might prevent bone fractures due to osteoporosis. Received: September 5, 2001 / Accepted: May 23, 2002     

Effects of combination treatment with alendronate and vitamin K2 on bone mineral density and strength in ovariectomized mice

Bisphosphonates increase bone mineral density (BMD) by suppressing remodeling space and elongating the duration of mineralization. Menatetrenone (vitamin K₂) reduces the incidence of fractures by improving bone quality through enhanced γ-carboxylation of bone glutamic acid residues of osteocalcin in osteoporotic patients. This study investigated the effects of combination treatment with alendronate (ALN) and vitamin K₂ on BMD and bone strength in ovariectomized (OVX) mice. Thirty-three female mice, 16 weeks of age, were assigned to four groups: (1) OVX-control group; (2) oral vitamin K₂ group; (3) subcutaneous ALN group; and (4) ALN + vitamin K₂ group. The treatment was started 4 weeks after OVX and continued for 4 weeks. BMD, geometric parameters measured by peripheral quantitative computed tomography, and mechanical strength at the femoral metaphysis and mid-diaphysis were evaluated after an 8-week treatment period. ALN alone significantly increased total BMD (20%, P < 0.05) and trabecular BMD (25%, P < 0.05), but not the mechanical parameters of the femur, compared with the OVX-control group. Combination treatment with ALN and vitamin K₂ increased not only total BMD (15%, P < 0.05) and trabecular BMD (32%, P < 0.05) but also maximum load (33%, P < 0.05) and breaking energy (25%, P < 0.05) of compression test at the distal metaphysis, and maximum load (20%, P < 0.05) and breaking force (33%, P < 0.05) of three-point bending test at the mid-diaphysis compared with the OVX-control group. These results suggest that ALN, alone or in combination with vitamin K₂, showed significant improvement in BMD, but that the combination treatment was more effective than ALN alone for improving bone strength in OVX mice.     

Preventive effects of sequential treatment with alendronate and 1 alpha-hydroxyvitamin D3 on bone mass and strength in ovariectomized rats

Because accumulating evidence has shown that bisphosphonates are unable to maintain their bone-sparing effects after the withdrawal of the drug, a replacement treatment is needed when bisphosphonate treatment cannot be continued for some reason. The present study investigated the preventive effects of alendronate followed by 1alpha(OH)D3 on the mass and mechanical strength of trabecular and cortical bones in ovariectomized rats. Sprague-Dawley rats were ovariectomized or sham-operated at 48 weeks of age. Ovariectomized rats treated with vehicle alone (OVX group) showed significant decreases in bone mineral density (BMD) and mechanical strength of the lumbar vertebra and the midfemur during a 20-week period after the operation as compared with sham-operated rats. These decreases were prevented by continuous treatment with alendronate (0.5 mg/kg/day, po) for 20 weeks (ALN-C group), whereas the values reverted to those of the OVX group when alendronate was withdrawn at 10 weeks (ALN-W group). The sequential treatment with alendronate and 1alpha(OH)D3 (0.05 microg/kg/day, po) for 10 weeks each (ALN --> 1alpha group) resulted in higher BMD and mechanical strength of the lumbar vertebra and the midfemur in this group than in the OVX and ALN-W groups. The increase in mechanical strength was proportional to that in BMD at both sites, suggesting that the stimulatory effects of these treatments on bone strength were due to those on bone mass. Analyses of histology, computed tomography, and biochemical markers confirmed the preventive effects of the sequential treatment. Therefore, we propose that 1alpha(OH)D3 may be a good choice to replace alendronate when alendronate treatment cannot be continued for some reason.     

染料木黄酮对去势大鼠骨组织形态计量学参数的影响

目的　研究染料木黄酮对去势大鼠股骨远端形态计量学参数的影响 ,为染料木黄酮防治骨质疏松提供理论依据。方法　雌性Wistar大鼠 4 7只 ,按体重随机分为 6组 :假手术组、去势对照组、去势 雌激素组 (2 0 μg/kg体重 )、去势 染料木黄酮组 (染料木黄桐剂量分别为 2 5、5 0、10 0mg/kg体重 )。饲养 3个月后处死 ,测定股骨形态计量学参数。结果　去势组与假手术组比较 ,骨小梁体积、平均骨小梁板密度和厚度减少 ,平均骨小梁板间隙和类骨质宽度增加 ,矿化延迟时间和类骨质成熟时间延长 ,且差异均具有显著性 (P <0. 0 5 )。染料木黄酮各组与去势组比较 ,骨小梁体积和平均骨小梁板厚度增加 ,平均骨小梁板间隙变窄 ,矿化延迟时间和类骨质成熟时间缩短 ,且差异均有显著性 (P <0 . 0 5 )。结论　染料木黄酮有促进骨形成 ,减少切除卵巢后骨量丢失的作用。     

大豆异黄酮减缓去卵巢大鼠骨量丢失的实验研究

目的研究大豆异黄酮对雌激素缺失状态下大鼠骨量丢失及骨转换的影响。方法 12月龄雌性SD大鼠40只随机分为4组,除假手术组大鼠行卵巢切除假手术外,其余均切除卵巢建立雌激素缺失模型。分组设计为:实验组[大豆异黄酮类40 mg／(kg．d)]及元素钙250 mg／(kg·d), 假手术组[蒸馏水)、实验对照组[元素钙250 mg／(kg·d)]及雌激素组[雌二醇30μg／100(g· 3d)及元素钙250mg／(kg·d)],除雌二醇皮下注射给予外,其余灌胃给予。28 d实验期满后处死大鼠,取股骨测定骨密度、股骨钙含量、股骨形态计量学相关指标,并测定血清碱性磷酸酶 (AKP)活性及血清骨钙素(OC)水平。结果实验组股骨骨密度、股骨钙含量稍高于假手术组和实验对照组,但未呈显著性差异(P>0．05);实验组骨小梁面积与假手术组无显著差异(P> 0．05);各组动物AKP活性无显著差异(P>0．05):实验组和雌激素组OC水平显著高于假手术组 (P<0．01)。结论大豆异黄酮具有弱雌激素样作用,可能通过促进成骨形成而减少雌激素缺失状态下的骨丢失,维持骨健康,预防绝经后骨质疏松。     

Strontium ranelate does not stimulate bone formation in ovariectomized rats

INTRODUCTION: Strontium ranelate (SrR) is suggested to function as a dual-acting agent in the treatment of postmenopausal osteoporosis with anti-resorptive and anabolic skeletal benefits. We evaluated the effects of SrR on the skeleton in ovariectomized (OVX) rats and evaluated the influence of dietary calcium. METHODS: Three-month old virgin female rats underwent ovariectomy (OVX, n = 50) or SHAM surgery (SHAM, n = 10). Four weeks post-surgery, rats were treated daily by oral gavage with distilled water (10 ml/kg/day) or SrR (25 or 150 mg/kg/day) for 90 days. Separate groups of animals for each dose of SrR were fed a low (0.1%) or normal (1.19%) calcium (Ca) diet. Static and dynamic histomorphometry, DXA, mu-CT, mechanical testing, and serum and skeletal concentrations of strontium were assessed. RESULTS: SrR at doses of 25 and 150 mg/kg/day did not increase bone formation on trabecular or periosteal bone surfaces, and failed to inhibit bone resorption of trabecular bone regardless of Ca intake. There were no improvements in bone mass, volume or strength with either dose of SrR given normal Ca. CONCLUSION: These findings demonstrate that SrR at dosages of 25 and 150 mg/kg/day did not stimulate an anabolic bone response, and failed to improve the bone biomechanical properties of OVX rats.     

Effects of alendronate on lumbar intervertebral disc degeneration with bone loss in ovariectomized rats

Background Context

Osteoporosis adversely affects disc degeneration cascades, and prophylactic alendronate (ALN) helps delay intervertebral disc degeneration (IDD) in ovariectomized (OVX) rats. However, there remains no information regarding whether ALN affects IDD with bone loss.

阿仑膦酸钠对骨小梁结构特性的作用

目的评价阿仑膦酸钠对骨小梁结构特性的作用。方法选取成年雌性Hound犬16只,随机分成两组:实验组8只,口服阿仑膦酸钠,剂量为0.5mg·kg-1·d-1;另选8只作为对照组。12周后处死16只犬并收集其L1和L2标本。直接从三维图像计算腰椎结构参数。结果实验组在服用阿仑膦酸钠后其L1和L2骨小梁体积分数各增加9.5%和7.7%,骨小梁厚度显著增加,但骨小梁间距保持恒定。与对照组相比,实验组骨小梁各向异性下降,骨表面积/体积比率显著降低,而骨表面密度增高。结论口服阿仑膦酸钠,剂量为时0.5mg·kg-1·d-1,短期内治疗能增强犬科骨小梁的结构特性。故阿仑膦酸钠短期内有增强健康骨小梁结构特性的作用。