rhPTH（1-34）治疗OVX大鼠骨质疏松延后效应的初步研究

目的观察重组人甲状旁腺激素（1-34）[rhPTH（1-34）]对卵巢摘除（OVX）大鼠骨质疏松症的治疗作用及停药后效应.方法应用双侧卵巢摘除方法建立模拟绝经后骨质疏松大鼠模型;给予皮下注射20μg/kg/d rhPTH（1-34）治疗8周,观察其骨量、骨生物力学、骨小梁形态计量及骨代谢相关血、尿生化指标,综合评价PTH对模型大鼠的治疗效果;同时观察停药8周后上述指标的变化.结果外源性PTH（1-34）治疗能显著增加模型大鼠的骨量、骨力学性能,改善骨微结构、增加骨转换.用药组的骨密度、股骨三点弯曲与腰椎压缩最大载荷、腰椎骨小梁百分面积显著高于对照组（P＜0.05～0.001）;血ALP（P＜0.05～0.01）与尿Pyd（P＜0.05）保持高水平;PTH停药8周后大鼠股骨与腰椎骨密度、股骨三点弯曲与腰椎压缩最大载荷及腰椎骨小梁百分面积均较停药前显著降低（P＜0.05～0.001）,但仍显著高于OVX对照组（P＜0.05～0.001）.结论外源性PTH（1-34）可显著增加OVX大鼠的骨量,提高骨力学性能,改善骨微结构,对卵巢摘除诱导的大鼠骨质疏松具有明显治疗作用;停药后出现骨量的快速丢失,骨力学性能下降等变化,但仍显示出其对OVX大鼠骨骼的保护作用.     

密盖息对骨质疏松大鼠治疗作用的实验研究

目的观察密盖息单独和联合中药龟鹿补肾液治疗对骨质疏松大鼠骨密度及骨代谢的影响,探讨密盖息对骨质疏松的治疗作用以及与血钙、磷、维生素D代谢的关系,以及与生长因子的关系。方法用摘除大鼠双侧卵巢的方式制备骨质疏松模型,用密盖息治疗4周后,换用中药龟鹿补肾液治疗4周,应用HOLOGIC第4代双能X线4500W骨密度仪测大鼠全身、腰椎、股骨上段骨密度值(BMD),用ELISA法测定血清IGF-1水平和血清25OHVitD浓度以及血淋巴细胞维生素D受体(VDR)含量。结果密盖息治疗4周,治疗Ⅰ组(OVX+密盖息组)和治疗Ⅱ组(OVX+密盖息+中药组)较模型对照组(OVX组)腰椎、股骨上段骨密度增高,组间之比有显著性差异(P<0.01,或0.01相似文献   

脉冲电磁场对绝经后骨质疏松症的治疗作用

目的 探讨低频率低强度脉冲电磁场(PEMFs)对绝经后骨质疏松症(OP)大鼠的治疗作用.方法 3～5月龄雌性SD大鼠经手术分别摘取两侧卵巢(OVX),对照组实行假性去除卵巢手术(sham),术后1月对手术组大鼠分组治疗,3个月后处死动物,检测大鼠股骨骨密度(BMD)、股骨生物力学指标、血清钙(Ca)、磷(P)、碱性磷酸酶(ALP)等生化指标.结果 与模型组大鼠相比,PEMFs治疗大鼠绝经后体重增长缓慢,BMD、右腿股骨承受应力明显增强,血清(Ca、P、ALP)值明显改善,提示PEMFs对绝经后雌激素缺乏引起的骨质疏松症大鼠有良好的治疗作用.     

rhPTH_((1-34))治疗OVX大鼠骨质疏松延后效应的初步研究

目的观察重组人甲状旁腺激素(134)[rhPTH(134)]对卵巢摘除(OVX)大鼠骨质疏松症的治疗作用及停药后效应。方法应用双侧卵巢摘除方法建立模拟绝经后骨质疏松大鼠模型;给予皮下注射20μgkgdrhPTH(134)治疗8周,观察其骨量、骨生物力学、骨小梁形态计量及骨代谢相关血、尿生化指标,综合评价PTH对模型大鼠的治疗效果;同时观察停药8周后上述指标的变化。结果外源性PTH(134)治疗能显著增加模型大鼠的骨量、骨力学性能,改善骨微结构、增加骨转换。用药组的骨密度、股骨三点弯曲与腰椎压缩最大载荷、腰椎骨小梁百分面积显著高于对照组(P<0.05～0.001);血ALP(P<0.05～0.01)与尿Pyd(P<0.05)保持高水平;PTH停药8周后大鼠股骨与腰椎骨密度、股骨三点弯曲与腰椎压缩最大载荷及腰椎骨小梁百分面积均较停药前显著降低(P<0.05～0.001),但仍显著高于OVX对照组(P<0.05～0.001)。结论外源性PTH(134)可显著增加OVX大鼠的骨量,提高骨力学性能,改善骨微结构,对卵巢摘除诱导的大鼠骨质疏松具有明显治疗作用;停药后出现骨量的快速丢失,骨力学性能下降等变化,但仍显示出其对OVX大鼠骨骼的保护作用。     

GYY4137对去卵巢诱导的骨质疏松大鼠的实验研究

目的探讨GYY4137对去卵巢诱导的骨质疏松大鼠的影响。方法将80只大鼠随机分为4组,采用雌性SD大鼠双侧卵巢全切除术(OVX)或假手术(Sham),建立骨质疏松模型,通过骨密度的检测确认模型建立成功,随后OVX大鼠给予腹腔注射GYY4137和阿仑膦酸钠治疗。测定血浆硫化氢(H2S)、血清碱性磷酸酶(ALP)活性、骨钙素(OCN)、降钙素、甲状旁腺激素和瘦素水平。采用双能X线骨密度仪测定左侧股骨密度(bone mineral density,BMD)。采用股骨三点弯曲试验获得股骨骨折的最大应力。结果成功建立OVX骨质疏松模型。OVX-GYY组在观察期内注射GYY4137显著提高血浆H2S水平(P 0.05)。12周时OVX-GYY组大鼠股骨密度增加(P0.05),OVX组股骨BMD值明显降低(P0.05)。双侧卵巢切除可引起大鼠生化骨代谢和血浆激素水平的改变(P均0.05)。卵巢切除还可以降低血钙、血磷和降钙素,增加甲状旁腺激素和瘦素。阿仑膦酸钠组和GYY4137组则显著改善上述指标(P均0.05)。结论 GYY4137对去卵巢大鼠骨质疏松有积极的治疗作用。     

金雀异黄酮对去势大鼠骨质疏松的影响

目的观察金雀异黄酮对实验性骨质疏松大鼠骨密度(bonemineral density,BMD)和血清骨代谢生化指标的影响。方法切除SD雌性大鼠双侧卵巢建立骨质疏松动物模型,给予金雀异黄酮皮下注射,治疗8w后监测大鼠腰椎及股骨的骨密度,检测血清骨碱性磷酸酶(ALP)、血清钙(Ca)、血清磷(P)等骨代谢生化指标。结果去势后的大鼠腰椎及股骨的骨密度降低;采用金雀异黄酮治疗后骨密度明显升高,与阴性对照组的比较差异具有统计学意义(P<0.05),与假手术组比较无显著性差异。假手术组和金雀异黄酮组血清ALP活性低于阴性对照组。结论金雀异黄酮可调节骨代谢,显著提高骨质疏松大鼠的骨密度。     

麦角甾苷治疗对去卵巢大鼠骨质疏松症保护机制研究

目的 探讨麦角甾苷(MJZG)治疗对去卵巢大鼠骨密度降低和骨量流失的潜在影响,并探索可能的机制。方法 通过双侧去卵巢构建骨质疏松大鼠模型;随后将大鼠随机分为假手术组(Sham)、去卵巢组(OVX)以及麦角甾苷(MJZG),每组10只;其中MJZG组大鼠接受麦角甾苷(100 mg/kg)治疗12周;待治疗截止时获取股骨标本和血液样品进一步检测股骨骨量、骨强度、骨代谢指标改变以及组织蛋白的表达。结果 术后12周,与Sham组相比,OVX组的大鼠骨小梁微观参数和骨密度和骨矿物质含量以及骨强度显著降低;而MJZG组大鼠BMD、BV/TV、Tb.N、Tb.Th和Tb.Sp以及最大载荷和弹性模量较OVX组明显改善(P<0.05)。MJZG组大鼠血清BGP、ALP、TRACP-5b和DPD水平较OVX组明显降低,组间差异有统计学意义(P<0.05)。WB检测观察到,和OVX组比较,MJZG组的TRAF6、RANKL、NF-κB和NFAT2的蛋白水平表达下调(P<0.05),而PI3K、AKT和c-Fos上调(P<0.05)。结论 MJZG可以通过抑制RANKL/TRAF6/N...     

不同治疗时间脉冲电磁场对去势大鼠股骨骨密度的影响

目的 通过采用不同治疗时间脉冲电磁场(pulsed electromagnetic fields, PEMFs)干预去势大鼠骨质疏松模型,观察大鼠股骨骨密度变化,探索PEMFs治疗骨质疏松症的最佳治疗时间.方法 将50只雌性3月龄SD大鼠随机分为假手术组、卵巢切除(ovariectomy, OVX)对照组、OVX后不同时间治疗组(OVX Ⅰ组、OVX Ⅱ组及OVX Ⅲ组),每组10只.假手术组大鼠仅切除卵巢周围部分脂肪组织,不切除卵巢;余各组大鼠均切除双侧卵巢,制备去势大鼠骨质疏松模型.OVX Ⅰ组、OVX Ⅱ组和OVX Ⅲ组大鼠每天分别用强度3.8×10-10A/m、频率8Hz干预20、40及60min,共30d;假手术组和OVX对照组不干预.观察各组大鼠一般情况,并于干预结束后次日处死大鼠,作左侧股骨骨密度测定.结果 术后OVX对照组大鼠毛发逐渐稀疏,活动迟缓,精神萎靡不振,反应较为迟钝;其余4组大鼠毛发光洁,精神及活动正常.假手术组、OVX对照组、OVX Ⅰ组、OVX Ⅱ组及OVX Ⅲ组股骨骨密度分别为(0.226±0.011)、(0.210±0.011)、(0.231±0.013)、(0.231±0.017)及(0.229±0.013)g/cm2,OVX对照组骨密度低于其他组(P<0.05),假手术组、OVX Ⅰ组、OVX Ⅱ组及OVX Ⅲ组组间比较,差异无统计学意义(P>0.05).结论 每日采用PEMFs对去势大鼠治疗20～60min能阻止其骨密度下降,接近正常水平,对骨质疏松症有良好的预防作用,且3种治疗时间对骨密度的维持效果相同.     

密骨方对去势大鼠骨质疏松后骨折愈合的影响

目的 观察密骨方对骨质疏松性骨折(OPF)的影响.方法 将90只雌性Wistar大鼠随机分为对照组(Sham),模型组(OVX)与密骨方治疗组(MGF),模型组及治疗组行卵巢摘除术,同时MGF组和OVX组大鼠均致其右侧股骨上1/3处骨折.MGF组按100 mg/(kg·d)的剂量灌胃给药,Sham组和OVX组给予同体积的生理盐水,每日1次,疗程分别为2周、4周、6周,用苏木素-伊红(HE)染色检测骨折端的形态学变化;用放射免疫法测定不同时段血清雌二醇(E2)、骨钙素(BGP)的表达;用生化法测定碱性磷酸酶(ALP)的表达.结果 MGF组血清E2在时间上有显著升高趋势(P＜0.05);MFG组血清BGP值在3个时间段有降低趋势,且差异有统计学意义(P＜0.05);MFG组血清ALP值总体比较有显著降低趋势(P＜0.05).结论 MGF有抑制破骨细胞的活性及促进骨折愈合的作用.     

普萘洛尔对去卵巢大鼠骨密度及血清IL-6的影响

目的 探讨普萘洛尔对去卵巢大鼠骨密度及对血清IL-6水平的影响。方法 50只健康雌性未交配6个月龄SD大鼠随机分为5组,每组10只:①假手术组(sham);②去卵巢(PVX)后雌激素治疗组(O E);③OVX后普萘洛尔治疗组(O p);①OVX后雌激素 普萘洛尔治疗组(O E P);⑤OVX后安慰剂组(OVX);OVX后1周开始经灌胃给予普萘洛尔8 mg·kg-1·d-1、皮下注射17β-雌二醇20μg·kg-1·d-1,共12周。动物处死时留取第3,4,5腰椎、血清标本,进行骨密度分析及血清IL-6水平测定。结果 O P、O E P、O E组的骨密度较手术组(OVX)明显增高(P<0.05),血清IL-6较OVX组明显下降(P<0.01)。结论 普萘洛尔能有效地预防OVX大鼠的骨丢失,同时降低血清IL-6水平。     

重组人甲状旁腺素（1-34)与雌激素对去卵巢大鼠骨代谢的影响

目的观察重组人甲状旁腺素(1-34)与雌激素单用和联用对去卵巢大鼠骨代谢的影响。方法选用雌性4月龄SD大鼠45只,随机分为5组:①假手术(Sham)8只;②去卵巢(OVX)9只;③雌激素治疗组(OVX E)10只:OVX2个月后给予苯甲酸雌二醇治疗6w;④PTH治疗组(OVX PTH)9只:OVX2个月后给予rhPTH(1-34)治疗6w;⑤雌激素与PTH联合治疗组(OVX E PTH)9只:OVX2个月后给予rhPTH(1-34)和E2联合治疗6w。观察各组大鼠胫骨近端松质骨骨小梁形态计量学参数,椎体生物力学指标及部分血清骨生化代谢指标。结果雌激素治疗组和PTH治疗组的骨静态参数均表现为骨量增加;雌激素治疗组的骨形成参数和骨吸收参数降低;PTH治疗组的骨形成指标明显升高,而骨吸收指标虽较Sham高,但较OVX组有所降低;E2与PTH联合治疗组与单用E2组和单用PTH组比较,骨量明显提高,骨转换率参数介于单用E2和单用PTH组之间。3个治疗组的生物力学指标较OVX组均有明显提高,其中E2与PTH联合治疗组改善最明显。结论雌激素和PTH可使去卵巢大鼠松质骨骨量增加和改善生物力学性能,两者联合治疗有协同作用。     

Bone mineral and collagen quality in humeri of ovariectomized cynomolgus monkeys given rhPTH(1-34) for 18 months.

A recent study of ovariectomized monkeys, treated with recombinant human parathyroid hormone (rhPTH)(1-34) at 1 or 5 mg/kg/day for 18 months or for 12 months followed by 6 months withdrawal from treatment, showed significant differences in the geometry and histomorphometry of cortical bone of the midshaft humerus. To determine the extent to which the rapid bone turnover and cortical porosity induced by rhPTH(1-34) in ovariectomized monkeys modified mineral content, mineral crystal maturity and collagen maturity (cross-link distribution) in the cortical periosteal and endosteal regions, cross-sections of the cortical bone of the mid-humerus, were examined using Fourier transform infrared imaging (FTIRI). FTIRI analyses demonstrated that rhPTH(1-34) altered bone mineral and collagen properties in a dose-dependent manner. Mineral crystal maturity and collagen cross-link ratio (pyridinoline/dehydro-dihydroxylysinonorleucine) on both endosteal and periosteal surfaces decreased relative to ovariectomized animals, consistent with new bone formation. These changes were partially sustained after withdrawal of the higher dose of rhPTH(1-34), suggesting a prolonged after-effect on bone properties for at least two bone remodeling cycles. In conclusion, treatment of ovariectomized monkeys with rhPTH(1-34) had significant effects on cortical bone mineral-to-matrix ratio, mineral crystal maturity, and collagen cross-link ratio. These were fully reversible when the 1-microg rhPTH(1-34) treatment was withdrawn, but only partially reversed when the 5-microg rhPTH(1-34) dose was withdrawn.     

Maintenance of increased bone mass after recombinant human parathyroid hormone (1-84) with sequential zoledronate treatment in ovariectomized rats.

The concept of lose, restore, maintain (LRM) for reversing existing osteoporosis was tested in rats. The withdrawal of PTH results in the loss of the acquired bone mass, but sequential therapy with zoledronate quite effectively maintained the PTH(1-84)-acquired bone quantity and quality. INTRODUCTION: Because antiresorptive agents against osteoporosis are presently quite limited, strong anabolic agents such as human parathyroid hormone (hPTH) are quite helpful. However, because hPTH(1-34) is available only through injection and has a critical side effect of causing bone tumors during life-long administration in the rat, it would be practical to use PTH for the shortest possible duration to obtain the maximal effect. To determine the effectiveness of the osteoporosis-reversing concept of lose, restore, and maintain (LRM), recombinant hPTH(1-84) [rhPTH(1-84)] and the respective antiresorptive agents were sequentially studied. MATERIALS AND METHODS: Thirty-six, 20-week-old Sprague-Dawley rats were used. Treatment started at the 25th week after ovariectomy, which was performed at 20 weeks of age, with 5 weeks of rhPTH(1-84) 100 microg/kg/day, 5 days/week, followed by the respective sequential therapies for 5 weeks as follows: (1) ovariectomized rats (OVX; n = 6), (2) sham-operated rats (SHAM; n = 6), (3) OVX rats with PTH maintenance (PTH-M; n = 6), (4) OVX rats treated with PTH and then PTH was withdrawn (PTH-W; n = 6), (5) PTH-treated OVX rats treated with 17beta-estradiol (PTH-E; 10 microg/day SC, 5 days/week; n = 6), and (6) PTH-treated OVX rats treated with zoledronate (PTH-Z; 12.5 microg/kg SC weekly; n = 6). BMD of the right femora was measured by DXA. microCT was used to measure the structural parameters of the second lumbar vertebrae. Three-point bending test of the femora and compressive tests of vertebrae were also performed. RESULTS: Bone quantity data showed that the BMD and most of the microstructural parameters were significantly higher in the PTH-M and PTH-Z groups than in the OVX and PTH-W groups (p < 0.05). Measurement of the cortical thickness revealed that only the PTH-M group showed a significant increase (p = 0.001). The ultimate force (Fu) at the midshaft of the femora was similar in the treated groups and stronger than in the OVX group (p < 0.05). However, in the vertebrae, the Fu of the PTH-M and PTH-Z groups was significantly higher, by approximately 44-47%, than in the OVX and PTH-E groups and showed a higher tendency than in the PTH-W group. CONCLUSION: PTH withdrawal resulted in the loss of acquired BMD, and sequential therapy with antiresorptives prevented further loss (17beta-estradiol versus zoledronate). The zoledronate after rhPTH(1-84) as a sequential regimen was quite consistently effective.     

间歇皮下注射人甲状旁腺激素不同片段(hFTH1-34及 hFTH1-84)对去卵巢大鼠股骨及腰椎骨量的影响

目的 比较间歇皮下注射人甲状旁腺激素不同片段（hPTH1-34)及（hPTH1-84)对完整雌性（Non-OVX)大鼠和去卵巢（OVX）大鼠股骨及腰椎1－4骨矿物含量（BMC）和骨密度（BMD）的影响。方法 Wistar雌性大鼠176只，分为hPTH1-34和hPTH1-84两大组（各80只及96只），每大组及各自分4组（每组各20只或24只），分别为：两组安慰剂组（未切卵巢及切卵巢）用安慰剂（PBS）进行皮下注射，每周3次，共2周；两组治疗组（未切卵巢及切卵巢）用hPTH1-34或hPTH1-84，皮下注射，每周3次，共2周。结果 1．卵巢切除术后3个月大鼠股骨及腰椎1－4BMC和BMD明显下降；2．两种片段的甲状旁腺激素（hPTH1-34及pPTH1-84)间歇注射均能使Non-OVX大鼠和OVX大鼠股骨及腰椎1－4BMC和BMD较相应对照组明显升高；且腰椎1－4较股骨的BMC和BMD升高更明显；3．OVX大鼠治疗后股骨与腰椎1－4BMC和BMD的升高率较Non-OVX大鼠更明显；OVX大鼠在治疗后股骨及腰椎骨量能恢复到去卵巢前水平；4．hPTH1-34较hPTH1-84更明显的使完整大鼠和OVX大鼠股骨BMC和BMD升高。结论 间歇皮下注射人甲状旁腺激素对大鼠股骨及腰椎骨量均有增高作用，尤其对腰椎的骨量以及对去卵巢大鼠骨量升高作用更明显；hPTH1-34片段对大鼠股骨骨量的增高作用强于hPTH1-84片段。     

Strontium Ranelate Enhances Callus Strength More Than PTH 1-34 in an Osteoporotic Rat Model of Fracture Healing

Treatment of an underlying disease is often initiated after the occurrence of an osteoporotic fracture. Our aim was to investigate whether teriparatide (PTH 1-34) and strontium ranelate affect fracture healing in ovariectomized (OVX) rats when provided for the first time after the occurrence of an osteoporotic fracture. We combined the model of an OVX rat with a closed diaphyseal fracture. Sixty Sprague Dawley rats were randomly assigned to four groups. Fracture healing in OVX rats after treatment with pharmacological doses of strontium ranelate and PTH 1-34 was compared with OVX and sham-treated control groups. After 28 days, the femur was excised and scanned by micro computed tomography and the callus evaluated, after which biomechanical torsional testing was performed and torque and toughness until reaching the yield point were analyzed. Only treatment with strontium ranelate led to a significant increase in callus resistance compared to the OVX control rats, whereas both PTH 1-34 and strontium ranelate increased the bone volume/tissue volume ratio of the callus. The PTH 1-34–increased trabecular bone volume within the callus was even higher compared to sham. As for the callus tissue volume, the increase induced by strontium ranelate was significant, contrary to the changes induced by PTH. Callus in strontium ranelate–treated animals is more resistant to torsion compared with OVX control rats. To our knowledge, this is the first report of the enhancement of fracture healing by strontium ranelate. Because both treatments enhance bone and tissue volume within the callus, there may be a qualitative difference between the calluses of PTH 1-34– and strontium ranelate–treated OVX rats. The superior results obtained with strontium ranelate compared to PTH in terms of callus resistance could be the consequence of a better quality of the new bone formed within the callus.     

Both hPTH(1-34) and bFGF increase trabecular bone mass in osteopenic rats but they have different effects on trabecular bone architecture.

Osteoporosis is a syndrome of excessive skeletal fragility that results from both the loss of trabecular bone mass and trabecular bone connectivity. Recently, bFGF has been found to increase trabecular bone mass in osteoporotic rats. The purpose of this study was to compare how trabecular bone architecture, bone cell activity, and strength are altered by two different bone anabolic agents, bFGF and hPTH(1-34), in an osteopenic rat model. MATERIALS AND METHODS: Six-month-old female Sprague-Dawley rats (n = 74) were ovariectomized (OVX) or sham-operated (sham) and maintained untreated for 2 months. Then OVX rats were subcutaneously injected with basic fibroblast factor (bFGF; 1 mg/kg, 5 days/week), human parathyroid hormone [hPTH(1-34); 40 microg/kg, 5 days/week], or vehicle for 60 days (days 60-120). Sham-operated and one group of OVX animals were injected with vehicle. Biochemical markers of bone turnover (urinary deoxypyridinoline cross-links; Quidel Corp., San Diego, CA, USA) and serum osteocalcin (Biomedical Technologies, Stroughton, MA, USA) were obtained at study days 0, 60, 90, and 120 and analyzed by ELISA. At death, the right proximal tibial metaphysis was removed, and microcomputed tomography was performed for trabecular bone structure and processed for histomorphometry to assess bone cell activity. The left proximal tibia was used for nanoindentation/mechanical testing of individual trabeculae. The data were analyzed with Kruskal Wallis and post hoc testing as needed. RESULTS: Ovariectomy at day 60 resulted in about a 50% loss of trabecular bone volume compared with sham-treated animals. By day 120 post-OVX, OVX + vehicle treated animals had decreased trabecular bone volume, connectivity, number, and high bone turnover compared with sham-operated animals [p < 0.05 from sham-, hPTH(1-34)-, and bFGF-treated groups]. Treatment of OVX animals with bFGF and hPTH(1-34) both increased trabecular bone mass, but hPTH(1-34) increased trabecular thickness and bFGF increased trabecular number and connectivity. Histomorphometry revealed increased mineralizing surface and bone formation rate in both bFGF and hPTH(1-34) animals. However, osteoid volume was greater in bFGF-treated animals compared with both the hPTH(1-34) and OVX + vehicle animals (p < 0.05). Nanoindentation by atomic force microscope was performed on approximately 20 individual trabeculae per animal (three animals per group) and demonstrated that elastic modulus and hardness of the trabeculae in bFGF-treated animals were similar to that of the hPTH-treated and sham + vehicle-treated animals. CONCLUSION: Both hPTH(1-34) and bFGF are anabolic agents in the osteopenic female rat. However, hPTH(1-34) increases trabecular bone volume primarily by thickening existing trabeculae, whereas bFGF adds trabecular bone mass through increasing trabecular number and trabecular connectivity. These results suggest the possibility of sequential treatment paradigms for severe osteoporosis.     

Effect of parathyroid hormone (hPTH[1-84]) treatment on bone mass and strength in ovariectomized rats.

Skeletal fragility in osteoporotic patients is a prominent underlying cause of low-trauma fractures of most bone sites in humans. Clinical research is now focused on developing treatment strategies, including anabolic agents such as parathyroid hormone (PTH), to recover osteoporosis-related bone loss. Female Sprague-Dawley rats (4.5 mo old) were allowed to become osteopenic for 10 wk postovariectomy. Eight rats were killed at the time of ovariectomy (-10 wk) as a baseline control; sham and ovariectomized (OVX) groups were killed at wk 0. Eight rats per group (sham, OVX + vehicle, OVX + hPTH [5 d/wk], and OVX + hPTH [3 d/wk]) were killed after 4, 8, 14, and 20 wk of treatment with 50 microg/kg of human parathyroid hormone (hPTH[1-84]). Bone mineral content and density were measured only in the vertebral body. Bone strength was evaluated in the vertebral body, femoral diaphysis, femoral neck, and distal femur. Significant, lasting osteopenia developed in the vertebral body of OVX rats by 10 wk postovariectomy. Bone mineral density of the vertebral body partially recovered by 8 wk and fully recovered to that seen in sham animals only by 20 wk posttreatment with either a 5 or 3 d/wk dosing schedule of PTH[1-84]. Therefore, hPTH[1-84] (50 microg/kg) given either 3 or 5 d/wk fully restores vertebral and femoral bone strength in osteopenic OVX rats.     

Combined treatment with PTH (1-34) and OPG increases bone volume and uniformity of mineralization in aged ovariectomized rats

The combination of PTH with OPG has been proposed as a potential therapy in patients with severe osteoporosis. In the present study, we examined the bone material of aged ovariectomized (OVX) rats treated either with PTH (1-34) or OPG alone or in combination of both. The micro- and nanostructural characteristics of the mineralized bone were evaluated using quantitative backscattered electron imaging (qBEI) and small-angle X-ray scattering (SAXS). Rats (n=68) were either sham-operated or ovariectomized (OVX) at the age of 3 months, and 15 months later, OVX animals were treated either with vehicle, OPG (10 mg/kg), PTH (80 microg/kg) or a combination of both during 5.5 months. All treatments were by subcutaneous injection, 3 days per week. Secondary metaphyseal spongiosa from distal femora was assessed for mineralized bone volume (BV/TV), for the mean Ca-concentration (Camean), the width of the bone mineralization density distribution (Cawidth), as well as the average mineral particle thickness parameter (T) and the degree of alignment of the mineral particles (rho). A remarkable increase of BV/TV up to 139% (P<0.001) was observed in the PTH-treated groups independently of OPG. Camean was slightly increased (+1.7%, P<0.05) in the OPG-treated group. Cawidth was reduced (-6.4%, P<0.01, and -8.9%, P<0.001) in animals treated with OPG and PTH+OPG, respectively. In contrast, Cawidth in sham-operated rats was 16.0% (P<0.001) higher than in OVX. The T parameter was not altered in the trabecular bone within the group of treated and untreated OVX rats. However, the non-ovariectomized animals exhibited a significantly lower T value (-7.1%, P<0.01) with respect to OVX. In conclusion, qBEI and SAXS data of OVX rats suggest that PTH alone was responsible for increase of bone volume, whereas OPG positively influenced the homogeneity and density of mineralization without affecting the nanostructure of the bone material.     

Intermittently administered human parathyroid hormone(1-34) treatment increases intracortical bone turnover and porosity without reducing bone strength in the humerus of ovariectomized cynomolgus monkeys.

Cortical porosity in patients with hyperparathyroidism has raised the concern that intermittent parathyroid hormone (PTH) given to treat osteoporotic patients may weaken cortical bone by increasing its porosity. We hypothesized that treatment of ovariectomized (OVX) cynomolgus monkeys for up to 18 months with recombinant human PTH(1-34) [hPTH(1-34)] LY333334 would significantly increase porosity in the midshaft of the humerus but would not have a significant effect on the strength or stiffness of the humerus. We also hypothesized that withdrawal of PTH for 6 months after a 12-month treatment period would return porosity to control OVX values. OVX female cynomolgus monkeys were given once daily subcutaneous (sc) injections of recombinant hPTH(1-34) LY333334 at 1.0 microg/kg (PTH1), 5.0 microg/kg (PTH5), or 0.1 ml/kg per day of phosphate-buffered saline (OVX). Sham OVX animals (sham) were also given vehicle. After 12 months, PTH treatment was withdrawn from half of the monkeys in each treatment group (PTH1-W and PTH5-W), and they were treated for the remaining 6 months with vehicle. Double calcein labels were given before death at 18 months. After death, static and dynamic histomorphometric measurements were made intracortically and on periosteal and endocortical surfaces of sections from the middiaphysis of the left humerus. Bone mechanical properties were measured in the right humeral middiaphysis. PTH dose dependently increased intracortical porosity. However, the increased porosity did not have a significant detrimental effect on the mechanical properties of the bone. Most porosity was concentrated near the endocortical surface where its mechanical effect is small. In PTH5 monkeys, cortical area (Ct.Ar) and cortical thickness (Ct.Th) increased because of a significantly increased endocortical mineralizing surface. After withdrawal of treatment, porosity in PTH1-W animals declined to sham values, but porosity in PTH5-W animals remained significantly elevated compared with OVX and sham. We conclude that intermittently administered PTH(1-34) increases intracortical porosity in a dose-dependent manner but does not reduce the strength or stiffness of cortical bone.     

Human parathyroid hormone 1-34 reverses bone loss in ovariectomized mice.

The experimental work characterizing the anabolic effect of parathyroid hormone (PTH) in bone has been performed in nonmurine ovariectomized (OVX) animals, mainly rats. A major drawback of these animal models is their inaccessibility to genetic manipulations such as gene knockout and overexpression. Therefore, this study on PTH anabolic activity was carried out in OVX mice that can be manipulated genetically in future studies. Adult Swiss-Webster mice were OVX, and after the fifth postoperative week were treated intermittently with human PTH(1-34) [hPTH(1-34)] or vehicle for 4 weeks. Femoral bones were evaluated by microcomputed tomography (microCT) followed by histomorphometry. A tight correlation was observed between trabecular density (BV/TV) determinations made by both methods. The BV/TV showed >60% loss in the distal metaphysis in 5-week and 9-week post-OVX, non-PTH-treated animals. PTH induced a approximately 35% recovery of this loss and a approximately 40% reversal of the associated decreases in trabecular number (Tb.N) and connectivity. PTH also caused a shift from single to double calcein-labeled trabecular surfaces, a significant enhancement in the mineralizing perimeter and a respective 2- and 3-fold stimulation of the mineral appositional rate (MAR) and bone formation rate (BFR). Diaphyseal endosteal cortical MAR and thickness also were increased with a high correlation between these parameters. These data show that OVX osteoporotic mice respond to PTH by increased osteoblast activity and the consequent restoration of trabecular network. The Swiss-Webster mouse model will be useful in future studies investigating molecular mechanisms involved in the pathogenesis and treatment of osteoporosis, including the mechanisms of action of known and future bone antiresorptive and anabolic agents.