番茄红素联合跑台运动对去卵巢大鼠骨质疏松模型的影响

目的通过观察番茄红素和跑台运动对去卵巢大鼠骨代谢指标的影响,探究番茄红素联合运动对去势大鼠骨代谢的作用机制。方法 6月龄雌性Wistar大鼠,按体质量随机分为6组:假手术组(Sham组)、去卵巢组(OVX组)、去卵巢+运动组(OVX+E组)、去卵巢+番茄红素组(OVX+L组)、去卵巢+运动+番茄红素组(OVX+E+L组)、去卵巢+阿伦磷酸钠组(OVX+AL组)。在12周后取材进行相关指标测试。结果 (1)单纯性的跑台运动能降低去势大鼠脂肪量,提高骨小梁数目的同时提高骨形成标志物骨钙素(osteocalcin,OC)水平,促进骨形成。(2)单纯性的番茄红素疗法能提高去势大鼠的子宫重量、血清甲状腺激素水平,提高相对骨体积、骨小梁厚度和骨内膜骨形成率,增强骨密度的同时降低骨代谢标志物Ⅰ型胶原氨基末端交联肽(NTx)水平,抑制骨吸收。(3)运动和药物交互作用能降低去势大鼠的脂肪百分比,提高血清雌二醇水平,降低尿8-OHd G和尿脱氧吡啶酚(DPD)水平。改善去势大鼠骨小梁结构参数,提高骨外膜骨形成率、骨强度和抗性变能力,改善全身骨密度。结论 (1)适度的跑台运动可以防止去势大鼠骨丢失,改善去势大鼠骨健康。(2)12周的番茄红素对去势大鼠骨代谢的治疗作用与阿仑膦酸钠效果类似,提高骨强度,降低体内氧化还原反应、加强抗氧化系统功能,维持骨代谢平衡。(3)番茄红素和运动表现出良好的协同作用,对去势大鼠骨重建具有积极的作用。     

硬化蛋白抗体和跑台运动对大鼠骨代谢的影响

目的通过对糖皮质激素诱导骨质疏松大鼠模型进行硬化蛋白和跑台运动的干预,研究硬化蛋白抗体和跑台运动对大鼠骨代谢的影响。方法雄性Wistar大鼠饲养到19周后,分为5组:C组(正常对照组)、M组(甲强龙对照组)、M+E组(甲强龙+运动组)、M+S组(甲强龙+硬化蛋白抗体组)、M+E+S组(甲强龙+运动+硬化蛋白抗体组)。结果 (1)注射甲强龙可以提高脂肪体重和骨细胞凋亡水平,降低全身和股骨骨矿物质含量,降低股骨骨密度和骨陷窝率,且伴随着股骨远端的骨小梁骨量的下降。(2)单纯性的运动可以提高骨量、骨陷窝率,同时可以降低脂肪体重、骨吸收标志物NTx和骨细胞凋亡水平,但运动不会影响骨矿物质含量和皮层骨参数结构。(3)单纯性的注射硬化蛋白抗体能增加骨形成标志物骨钙素(osteocalcin,OC),防止甲强龙对骨质量的不良影响,进而提高骨含量、骨密度以及骨体积百分比。硬化蛋白抗体可以增加远端和中段部分的皮质骨参数,防止骨陷窝率下降和因甲强龙诱导产生的骨细胞凋亡水平上升。(4)运动和硬化蛋白交互作用时,可以提高骨密度、皮质骨参数,促进骨形成抑制细胞凋亡的发生。结论单纯性的Scl-Ab注射方案可以预防糖皮质激素治疗对骨量的不良影响,显著提高皮质骨骨量和骨强度。单纯性的跑台运动方案可以降低脂肪含量,并在不影响皮质骨的情况下防止骨小梁丢失。运动与硬化蛋白之间表现出良好的协同作用,对治疗糖皮质激素诱导骨质疏松症具有积极作用。     

二甲双胍对去卵巢大鼠骨质疏松症的影响及机制研究

目的 以雌二醇为对照,观察二甲双胍(metformin, MF)对去卵巢大鼠骨密度及骨矿含量的影响,并从细胞、分子水平探究MF可能的骨保护机制。方法 将60只雌性SD大鼠随机均分4组：假手术（SHAM）组、去卵巢（OVX）组、去卵巢+二甲双胍（OVX+MF）组和去卵巢+雌二醇(OVX+E2 )组。分组灌胃给药60 d后测量大鼠右侧胫骨骨密度和骨矿含量;分离培养各组大鼠骨髓间充质干细胞（BMSCs）并诱导其向成骨细胞分化,用MTT法测定细胞活性及增殖能力;测定各组碱性磷酸酶（ALP）活性、矿化结节数目、钙含量以及I型胶原（collagen type I）、骨钙素（OC）、骨保护素 (OPG)、NFκB受体的配体 (RANKL)、白细胞介素-6（IL-6）基因表达水平。结果 与OVX组相比,OVX+MF组和OVX+E2组成骨细胞的增殖能力与ALP活性明显增强,骨密度、骨矿含量以及钙沉积量显著增加(P均<0.05),且两组collagen type I、OC、OPG mRNA的表达水平显著升高,而RANKL、IL-6mRNA表达明显受到抑制;但OVX+MF组去卵巢大鼠成骨细胞的增殖能力、ALP活性、钙沉积量、collagen type I、OC、OPG mRNA表达水平低于OVX+E2组,RANKL、IL-6mRNA表达高于OVX+E2组（P均<0.05）;与SHAM组比较,OVX+MF组的collagen type I、OC、OPG mRNA的表达水平更高（P<0.05）。结论 二甲双胍可能通过OPG/RANKL/RANK信号通路促进BMSCs向成骨细胞分化,有效逆转去卵巢大鼠骨质疏松的状态,这种潜在的骨保护作用可能会改善糖尿病引起的骨质疏松。     

运动加一氧化氮供体治疗去卵巢大鼠骨质疏松的实验研究

目的观察运动加一氧化氮供体左旋精氨酸(L-Arg)对去卵巢大鼠的影响。方法60只SD雌性大鼠,随机分成六组:正常对照组(SHAM)、去卵巢手术组(OVX)、雌激素对照组(OVX+ES)、运动组(OVX+ET)、左旋精氨酸组(OVX+L-Arg)、运动+左旋精氨酸组(OVX+ET+L-Arg),每组10只,12周后进行骨密度、生物力学以及骨代谢指标测定。结果运动+L-Arg组的大鼠的体重在各实验组中最接近正常对照组;运动+L-Arg组的大鼠全身和腰椎部以及股骨的骨密度提高非常明显,是各组中最高的;经单纯运动、单纯L-Arg以及运动+L-Arg治疗后的去卵巢大鼠的股骨部位的骨矿含量(BMC)有显著提高。结论运动+左旋精氨酸是一种安全、可靠、实用、有效的骨质疏松的防治方法,值得推广。     

黄芪多糖治疗对去卵巢诱导骨质疏松大鼠骨密度、骨量和骨代谢的影响

目的探索黄芪多糖对去卵巢大鼠骨量和骨代谢以及BMP-2/Smads信号通路的影响。方法30只雌性SD大鼠进行去卵巢手术或假手术。正常饲养12周后被分为黄芪多糖组(ASNT组)、对照组(CON组)和去卵巢组(OVX组),其中黄芪多糖组每天给予400 mg/kg黄芪多糖治疗。通过骨密度、骨代谢指标、Micro-CT以及WB检测评估ASNT对骨质疏松症大鼠骨量、骨代谢以及BMP-2/Smads信号通路的影响。结果经过12周治疗,ASNT组大鼠骨密度较OVX组显著增加(P<0.05);ASNT治疗12周可以降低血清ALP和OC水平,增加血钙含量,增加股骨骨密度。经过12周治疗,ASNT组大鼠骨体积分数(BV/TV)、表面积体积分数(BS/TV)、骨小梁厚度(Tb.Th)、骨小梁数目(Tb.N)较OVX组显著增加;而骨小梁间隙(Tb.Sp)较OVX组显著降低,差异比较有统计学意义(P<0.05)。WB结果表明OVX大鼠骨组织的BMP-2/Smsds信号通路受到抑制;ASNT可以通过上调BMP-2、p-Smad1和p-Smad5的表达显著激活BMP-2/Smsds信号通路传导。结论研究表明ASNT对去卵巢大鼠骨密度和骨量具有保护作用,可能和激活BMP-2/Smads信号通路有关。     

异紫杉脂素治疗对去卵巢大鼠骨量流失和骨密度降低保护作用的机制研究

目的探索异紫杉脂素(isotaxiresinol,IXO)对去卵巢大鼠骨密度和骨量的影响,并探讨其作用机制。方法将大鼠随机分为以下各组:假手术组(Sham)、去卵巢大鼠组(OVX)、去卵巢大鼠+异紫杉脂素组(IXO)。其中IXO组大鼠给予异紫杉脂素100 mg/(kg·d)治疗12周。Micro-CT和HE切片观察骨组织变化。通过ELISA检查用于分析骨代谢指标,进行蛋白质印迹分析以评估PI3K、Akt和RUNX-2的蛋白表达。结果 12周时,OVX组大鼠骨密度和骨量较Sham组显著降低。而IXO能显著改善去卵巢大鼠的骨密度和股骨干骺端骨小梁微观结构。去卵巢大鼠在IXO给药治疗后可显著降低P1NP和β-CTX水平(P0.05);用IXO治疗可上调去卵巢大鼠的PI3K、Akt和RUNX-2蛋白表达。结论本研究提示异紫杉脂素可以通过激活PI3K/Akt信号通路对去卵巢大鼠骨量流失和骨密度降低起到保护作用。     

去卵巢对大鼠皮质骨微结构、骨密度及生物力学的影响

目的 应用显微CT和四点弯曲实验观察去卵巢对大鼠股骨皮质骨骨密度、微结构及生物力学性能的影响.方法 24只7月龄雌性SD大鼠随机分为去卵巢(OVX)组和假手术(Sham)组,于手术后3周、15周各处死6只,显微CT扫描左侧股骨中段.右侧股骨行四点弯曲试验.结果 去卵巢3周至15周,OVX组股骨皮质骨内径周长、外径周长、皮质骨面积、骨髓腔面积、截面总面积骨密度、最大力、弹性模量、断裂强度与Sham组相比无明显差异(P＞0.05).OVX组15周弹性模量比3周低36％ (P ＜0.05).结论 去卵巢15周内大鼠股骨中段皮质骨微结构及其骨密度和股骨力学性能无明显变化,但去卵巢组股骨生物力学性能减退较快.     

中等强度跑台运动对去卵巢大鼠后肢骨骨矿物含量和骨密度的双重调节作用

目的 观察中等强度跑台运动对去卵巢大鼠后肢骨骨矿物含量(BMC)和骨密度(BMD)的影响.方法 将60只3月龄未经产雌性SD大鼠按体重随机分为假手术、去卵巢静止、去卵巢运动Ⅰ、去卵巢运动Ⅱ、去卵巢运动Ⅲ和去卵巢运动Ⅳ 6个组.各运动组经1周的跑台适应训练后,按实验设计分别进行为期14周的正式跑台训练.实验结束时,腹主动脉取血处死大鼠,双能χ-射线骨密度仪检测右侧游离股骨和胫骨的BMC和BMD.结果 ①与假手术组相比,去卵巢静止组股骨近端和远端以及胫骨近端BMC和BMD显著下降,但股骨中段以及胫骨中段和远端BMC和BMD无显著变化.②与去卵巢静止组相比,去卵巢运动Ⅰ组股骨近端和远端BMC显著增加,股骨中段以及胫骨3个部位BMC均无显著变化;去卵巢运动Ⅱ组和Ⅲ组股骨和胫骨3个部位BMC 均无显著变化;去卵巢运动Ⅳ组股骨3个部位BMC均无显著变化,而胫骨3个部位BMC均显著下降.③与去卵巢静止组相比,去卵巢运动Ⅰ组股骨近端和远端以及胫骨近端BMD 显著增加, 而股骨中段和胫骨中段和远端BMD无显著变化;去卵巢运动Ⅱ组和Ⅲ组股骨和胫骨任何部位BMD均没有显著变化;去卵巢运动Ⅳ组股骨3个部位BMD无显著变化,而胫骨3个部位BMD却显著下降.结论 较低中等强度跑台运动能减缓去卵巢大鼠股骨近端和远端骨矿物含量和骨密度的下降;而较高中等强度跑台运动却能加速去卵巢大鼠胫骨近端骨矿物含量和骨密度的下降.     

青年去势及老龄雌性大鼠骨质疏松模型比较及其临床护理意义

目的 建立青年去势及老龄雌性大鼠骨质琉松模型,探讨两种雌性大鼠骨质疏松模型骨组织微观结构、骨矿及骨负荷改变情况及潜在机制,为女性骨质疏松的临床护理干预寻找相应的理论依据.方法 32只1月龄雌性SpragueDawley(SD)大鼠,同等条件下饲养,饲养至4个月按体重随机分成青年去势及假手术对照组大鼠16只、老龄雌性及对照组大鼠16只,进行去势及老龄骨质疏松造模.比较青年去势组(Ovariecromized rats,8只,OVX组)和老龄骨质疏松组(Senile Female Osteoporotic Rats,8只,SF组)大鼠骨质改变情况.结果 OVX组大鼠去卵巢8周出现骨质疏松改变,SF组大鼠22月龄自然衰老出现骨质疏松改变.OVX组骨小梁宽度显著大于SF组(P<0.05);两组模型之间腰椎及股骨密度差异不显著(均P>0.05),但OVX组股骨最大负荷显著高于SF组(P<0.01);OVX组骨钙水平显著高于SF组(P<0.01).但两组血钙水平差异不显著(P>0.05).结论 4月龄大鼠去卵巢8周以及自然饲养22月龄雌性大鼠可分别作为女性绝经后及老年女性骨质疏松的模型.老龄骨质疏松模型在骨微观结构、骨生物力学特性、骨矿水平含量方面的负性改变更甚于青年去势模型,提示对女性骨质疏松症患者的护理干预措施应侧重于不同年龄阶段及骨代谢特点进行.     

牛膝提取物对去卵巢大鼠骨密度、骨转换及Ⅰ型胶原蛋白表达的影响

目的 观察牛膝醇提取物对去卵巢骨质疏松大鼠骨密度(BMD)、骨转换和骨组织Ⅰ型胶原蛋白表达的影响.方法 背侧切口切除大鼠双侧卵巢,分为去卵巢组,牛膝提取物高、中、低剂量组和雌激素对照组,另设一假手术组,分别给予基础饲料和不同剂量治疗药物,12w后使用双能X线骨密度仪测量股骨、胫骨和腰椎的骨密度;采用酶联免疫吸附法对骨转换指标血清骨碱性磷酸酶(BAP)、血清骨钙素(BGP)、抗酒石酸酸性磷酸酶(TRACP)、尿Ⅰ型胶原氨基末端肽(NTx)/肌酐比值(NTx/Cr)进行测定,并利用Western免疫印迹法检测骨组织Ⅰ型胶原蛋白表达的变化.结果 大鼠去势后骨密度和Ⅰ型胶原蛋白的表达显著下降(P<0.01),骨转换指标有较大变化.牛膝醇提取物高、中剂量组可使去势大鼠骨密度和Ⅰ型胶原蛋白的表达显著提高,改善骨转换指标的变化,且存在一定的剂量-效应关系.结论 牛膝醇提取物能提高去势大鼠的骨密度和Ⅰ型胶原蛋白的表达.     

Combined effects of exercise and propranolol on bone tissue in ovariectomized rats.

The bone response to physical exercise may be under control of the SNS. Using a running session in rats, we confirmed that exercise improved trabecular and cortical properties. SNS blockade by propranolol did not affect this response on cortical bone but surprisingly inhibited the trabecular response. This suggests that the SNS is involved in the trabecular response to exercise but not in the cortical response. INTRODUCTION: Animal studies have suggested that bone remodeling is under beta-adrenergic control through the sympathetic nervous system (SNS). However, the SNS contribution to bone response under mechanical loading remains unclear. The purpose of this study was to examine the preventive effect of exercise coupled with propranolol on cancellous and cortical bone compartments in ovariectomized rats. MATERIALS AND METHODS: Six-month-old female Wistar rats were ovariectomized (OVX, n = 44) or sham-operated (n = 24). OVX rats received subcutaneous injections of propranolol 0.1 mg/kg/day or vehicle and were submitted or not submitted to treadmill exercise (13 m/minute, 60 minutes/day, 5 days/week) for 10 weeks. Tibial and femoral BMD was analyzed longitudinally by DXA. At death, the left tibial metaphysis and L(4) vertebrae were removed, and microCT was performed to study trabecular and cortical bone structure. Histomorphometric analysis was performed on the right proximal tibia. RESULTS: After 10 weeks, BMD and trabecular strength decreased in OVX rats, whereas bone turnover rate and cortical porosity increased compared with the Sham group (p < 0.001). Either propranolol or exercise allowed preservation of bone architecture by increasing trabecular number (+50.35% versus OVX; p < 0.001) and thickness (+16.8% versus OVX; p < 0.001). An additive effect of propranolol and exercise was observed on cortical porosity but not on trabecular microarchitecture or cortical width. Biomechanical properties indicated a higher ultimate force in the OVX-propranolol-exercise group compared with the OVX group (+9.9%; p < 0.05), whereas propranolol and exercise alone did not have any significant effect on bone strength. CONCLUSIONS: Our data confirm a contribution of the SNS to the determinants of bone mass and quality and show a antagonistic effect of exercise and a beta-antagonist on trabecular bone structure.     

Partial Prevention of Long-Term Femoral Bone Loss in Aged Ovariectomized Rats Supplemented with Choline-Stabilized Orthosilicic Acid

Silicon (Si) deficiency in animals results in bone defects. Choline-stabilized orthosilicic acid (ch-OSA) was found to have a high bioavailability compared to other Si supplements. The effect of ch-OSA supplementation was investigated on bone loss in aged ovariectomized (OVX) rats. Female Wistar rats (n = 58, age 9 months) were randomized in three groups. One group was sham-operated (sham, n = 21), and bilateral OVX was performed in the other two groups. OVX rats were supplemented orally with ch-OSA over 30 weeks (OVX1, n = 20; 1 mg Si/kg body weight daily) or used as controls (OVX0, n = 17). The serum Si concentration and the 24-hour urinary Si excretion of supplemented OVX rats was significantly higher compared to sham and OVX controls. Supplementation with ch-OSA significantly but partially reversed the decrease in Ca excretion, which was observed after OVX. The increase in bone turnover in OVX rats tended to be reduced by ch-OSA supplementation. ch-OSA supplementation increased significantly the femoral bone mineral content (BMC) in the distal region and total femoral BMC in OVX rats, whereas lumbar BMC was marginally increased. Femoral BMD was significantly increased at two sites in the distal region in OVX rats supplemented with ch-OSA compared to OVX controls. Total lumbar bone mineral density was marginally increased by ch-OSA supplementation. In conclusion, ch-OSA supplementation partially prevents femoral bone loss in the aged OVX rat model.     

跑步运动配合银杏叶提取物摄入对去卵巢肥胖骨质疏松大鼠骨密度、血脂和抗氧化能力影响研究

目的探讨跑步运动配合银杏叶提取物摄入对骨密度、骨代谢、血脂和抗氧化能力的影响效果。方法利用80只雌性SD大鼠,随机分为去卵巢高脂组和对照组,去卵巢高脂组进行卵巢切除手术,对照组进行假手术,术后去卵巢高脂组进行高脂饲料喂食,对照组进行正常喂食,共进行6周;将接受切除卵巢手术和高脂喂食的的大鼠又随机分为模型组(M组)、银杏叶组(G组)、运动组(R组)、银杏叶+运动组(GE组),接受假手术和正常喂食的大鼠,为假手术组(S组)。进行12周干预,干预结束后,将大鼠置入代谢笼,采集尿样,后进行大鼠的腹腔静脉取血,对大鼠进行骨扫描、血液生化指标检查、骨代谢标志物检查。结果体重方面,在干预后3、6、9、12周M组大鼠体重显著高于S组,P0.05,R组、G组、GR组大鼠体重有逐渐上升趋势,但是在3、6、9、12周均显著低于M组,P0.05。骨密度和骨代谢方面,M组大鼠BMD、血清雌二醇水平显著低于R组、G组GR组、S组大鼠,P0.05。M组大鼠MDA水平显著高于S组、R组、G组和GR组,P0.05;M组大鼠血清OC、ALP、尿液DPD/Cre、Ca/Cre、P/Cre显著高于S组、R组、G组和GR组,P0.05。抗氧化方面,M组大鼠CAT、GSH-PX水平显著低于S组、R组、G组和GR组,P0.05;血脂方面,M组大鼠血液TG、TC水平显著高于S组、R组、G组和GR组,P0.05。结论去卵巢肥胖骨质疏松大鼠利用跑步运动配合摄入银杏叶提取物或单纯摄入银杏叶提取物进行中长期干预治疗能够增加骨密度和雌激素水平,降低骨吸收和骨转换率、降低体重和血脂水平、增加抗氧化能力。     

Prostaglandin E2 enhances cortical bone mass and activates intracortical bone remodeling in intact and ovariectomized female rats

To assess the efficacy of prostaglandin E2 (PGE2) in augmenting cortical bone mass, graded doses of PGE2 were subcutaneously administered for 30 days to seven-month old sham-ovariectomized (SHAM) and ovariectomized (OVX) rats. Both groups were operated at three months of age. Histomorphometric analyses of double fluorescent labeled tibial shafts were performed on basal control, OVX, and SHAM rats treated with 0, 0.3, 1, 3, and 6 mg PGE2/kg/d for 30 days. Baseline aging data showed increased cortical tissue and cortical bone area and reduced bone formation parameters at the periosteal and endocortical bone envelopes between three and eight months of age. The tibial shafts of OVX rats compared to SHAM controls showed elevated periosteal mineral apposition rate and endocortical bone formation parameters. PGE2 administration to OVX and SHAM rats increased cortical bone by the addition of new circumferential bone on the endocortical and periosteal surfaces, as well as woven cancellous bone in the marrow region. Stimulated osteoblastic recruitment and activity enhanced bone formation at all bone surfaces. The new bone was both lamellar and woven in nature. PGE2 treatment also activated intracortical bone remodeling (not seen in untreated eight-month old rats), creating a porous cortex. Thus, PGE2 administration activated cortical bone modeling in the formation mode (A----F), as well as intracortical bone remodeling (A----R----F). PGE2 administration to OVX rats resulted in more intracortical bone remodeling, periosteal bone formation, and new cancellous bone production than observed in PGE2 treated controls. The findings that PGE2 administration to OVX and intact female rats increases cortical bone mass, coupled with observations that mouse, rat, dog, and man respond similarly to PGE2, suggest that PGE2 administration may be useful in the prevention and treatment of postmenopausal osteoporosis.     

Correlation among geometric,densitometric, and mechanical properties in mandible and femur of osteoporotic rats

We have previously demonstrated bone loss of the mandible and femur in experimental osteoporotic rats and its prevention by medication, using peripheral quantitative computed tomography (pQCT). In the present study, the mechanical properties of the mandible and femur and the correlation to their geometric and densitometric properties were studied in ovariectomized rats with or without etidronate treatment. Fifty-four Wistar strain SPF female rats, 26 weeks old, were randomly assigned to four groups: (1) Basal group (12 rats, 1.0% Ca diet); (2) Sham group (Sham-operated, 12 rats, 0.1% Ca diet); (3) OVX group (ovariectomized, 15 rats, 0.1% Ca diet); (4) Treated group (OVX + etidronate, 15 rats, 0.1% Ca diet). Total bone mineral density (BMD), cortical BMD, cross-sectional cortical bone area, cross-sectional cortical bone thickness, crosssectional moment of inertia (CSMI), and polar strength index (SSI) of the mandible and femur were measured by pQCT. The failure load of mandible and femur was evaluated by three-point bending. The failure load of both bones was significantly lower in the Sham group compared with the Basal group. The OVX group further had a 8% and 7% decrease in the failure load for mandible and femur, respectively, compared to the Sham group. Treatment with etidronate led to an increase in the failure load compared with the OVX group. The failure load was related to the pQCT-assessed variables, especially with cortical bone area and total BMD. Moreover, the geometric and densitometric properties and failure load in the mandible showed a correlation to those in the femur.     

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.     

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.