The effects of binge alcohol exposure on bone resorption and biomechanical and structural properties are offset by concurrent bisphosphonate treatment

BACKGROUND: Chronic alcohol consumption reduces bone mass and strength, increasing fracture risk for alcohol abusers. Mechanisms underlying this vulnerability involve modulation of bone remodeling. Direct effects of alcohol on bone formation have been documented; those on bone resorption are less well studied. Skeletal effects of exposure to high blood alcohol concentrations (BAC's) attained during binge drinking have not been studied. We examined the effects of repeated binge-like alcohol treatment on bone resorption, bone mineral density and vertebral compressive strength in adult male rats treated with the aminobisphosphonate, risedronate. METHODS: A binge alcohol exposure model was developed using intraperitoneal (IP) injection to administer a 20% (vol/vol) alcohol/saline solution (3 g/kg, 1X/day) on four consecutive days for 1, 2 or 3 weeks in 400 g rats, with and without weekly risedronate treatment (0.5 mg/kg, 1X/week). Total serum deoxypyridinoline (Dpd) a crosslink of bone type collagen released during resorption was measured by ELISA. Bone mineral density (BMD) was measured using peripheral quantitative computed tomography (pQCT). Vertebral compressive strength was determined using an Instron materials testing machine. Trabecular integrity was analyzed by computer-aided trabecular analysis system (TAS). RESULTS: Peak BAC's averaged 308.5 +/- 12 mg/dL; average BAC was 258.6 +/- 28.7 mg/dL at time of euthanasia. No significant effects of treatment were observed after 1 or 2 weeks of binge alcohol exposure. At 3 weeks of alcohol treatment serum Dpd was significantly increased (205%, p < 0.05) over controls. Bone mineral density (BMD) in cancellous bone of distal femur and lumbar spine were significantly decreased (34% and 21% respectively, p < 0.01) after 3 weeks of binge treatment. Vertebral (L4) compressive strength (maximum load sustained before failure) also decreased (27%, p < 0.05) after 3 binge alcohol cycles. Risedronate maintained the Dpd level (p < 0.01), BMD (p < 0.001) and vertebral structural biomechanical properties (p < 0.01) of binge-treated rats at control levels (E vs ER). Indices of trabecular architectural integrity [Trabecular bone volume/tissue volume (BV/TV), bone area (BAR) and trabecular separation (Tb.Sp)] analyzed at week 3 showed (BV/TV) and (BAR) were significantly reduced in alcohol-binged rats (p < 0.01), while (Tb.Sp) was significantly increased (p < 0.01). Risedronate also maintained the trabecular architectural indices of binge-treated rats at control levels (E versus ER, p < 0.01). CONCLUSIONS: In adult male rats, BAC's reflective of those attained during alcoholic binge drinking may affect the skeleton in part by stimulating bone resorption, an effect mitigated by risedronate.     

大鼠去卵巢后不同时期骨微结构和力学性能的变化特征

目的揭示大鼠在去卵巢后不同时期腰椎松质骨微结构退变的变化特征,探讨骨整体力学性能下降的同时可能存在的各种适应性代偿性变化。方法50只7月龄SD大鼠随机分为基线、去卵巢组（OVX组）和假手术组（SHAM）。基线组10只,其余每组均20只。实验开始时先将基线组10只处死,OVX组和SHAM组分别在手术后3周、15周各处死10只,留取动脉血清及腰椎标本,骨微结构、力学和生化指标的测定。结果去卵巢后3周时OVX组表观骨密度、骨体积分数、骨小梁厚度和骨小梁数量均较SHAM和基线降低（P〈0．05）,各向异性度较基线下降（P〈0．05）而与SHAM组无统计学差异。骨小梁面积密度、骨小梁间隔和结构模型指数均较SHAM和基线组增加（P〈0．05）。去卵巢后3周时OVX组最大应力、弹性模量、血清TRAP-5b和骨细胞密度均低于基线（P〈0．05）而与SHAM组无统计学差异。去卵巢后15周时OVX组表观骨密度、骨体积分数、骨小梁数量和联接密度、最大应力、TRAP-Sb和骨细胞密度均较SHAM和基线组降低（P〈0.05）,骨小梁结构模型指数、骨小梁间隔和各向异性度均较SHAM和基线组增加（P〈0．05）,骨小梁面积密度和厚度均与SHAM和基线组无统计学差异。结论大鼠去卵巢后腰椎骨量快速丢失,骨微结构逐渐退变,而血清TRAP-5b水平下降及骨细胞密度、骨小梁各向异性度和厚度的适应性增加,可能在一定程度上代偿骨力学性能的下降,有利于维持骨结构的完整性。     

Sequential treatment with basic fibroblast growth factor and PTH is more efficacious than treatment with PTH alone for increasing vertebral bone mass and strength in osteopenic ovariectomized rats

The study was designed 1) to determine whether treatment with basic fibroblast growth factor (bFGF) and PTH is more efficacious than treatment with PTH alone for increasing bone mass and strength and improving trabecular microarchitecture in osteopenic ovariectomized rats, and 2) to assess whether prior and concurrent administration of the antiresorptive agents estrogen and risedronate suppresses the bone anabolic response to treatment with bFGF alone and sequential treatment with bFGF and PTH. Three-month-old female Sprague Dawley rats were ovariectomized (OVX) or sham-operated (sham) and maintained untreated for 1 yr. Baseline sham and OVX rats were killed at this time (15 months of age). Groups of rats were injected sc with estrogen (10 microg/kg, 4 d/wk), risedronate (5 microg/kg, 2 d/wk), or vehicle. At the end of the second week of antiresorptive treatment, catheters were inserted into the jugular veins of all rats, and vehicle or bFGF at a dose of 250 microg/kg was injected daily for 14 d. Three groups of rats were killed at the end of bFGF treatment. The remaining rats were continued on their respective antiresorptive therapy and injected sc with vehicle or synthetic human PTH-(1-34) at a dose of 80 microg/kg, 5 d/wk, for 8 wk. Lumbar vertebrae were processed for cancellous bone histomorphometry and biomechanical testing. Ovariectomy resulted in a decrease in vertebral bone mass and strength. Treatment of OVX rats for 14 d with bFGF markedly increased osteoblast surface, osteoid surface, and osteoid volume compared with vehicle treatment of sham and OVX rats. Furthermore, osteoid bridges were observed extending between preexisting trabeculae in bFGF-treated OVX rats. Prior and concurrent administration of estrogen and risedronate did not suppress these bone anabolic effects of bFGF. Treatment of OVX rats with PTH alone increased vertebral cancellous bone mass and strength to the level of vehicle-treated sham rats. Sequential treatment of OVX rats with bFGF and PTH further augmented vertebral bone mass and strength to a level above that observed in OVX rats treated with PTH alone. The improvements in bone mass and strength were associated with an increase in trabecular thickness in OVX rats treated with PTH alone and with an increase in trabecular thickness and node to terminus ratio, an index of trabecular connectivity, in OVX rats treated sequentially with bFGF and PTH. Cotreatment with estrogen and risedronate did not suppress the anabolic response of bone to bFGF and PTH. In fact, a trend for an even greater increase in cancellous bone mass and node to terminus ratio was observed in OVX rats treated with risedronate, bFGF, and PTH. These findings indicate that sequential treatment with bFGF and PTH is more efficacious than treatment with PTH alone for increasing bone mass and strength and improving trabecular microarchitecture in osteopenic OVX rats.     

去卵巢大鼠椎体松质骨骨小梁微结构改变及其对生物力学的影响

目的观察骨质疏松和正常状态下椎体松质骨的微观结构改变,分析其对骨生物力学的影响。方法将12只4月龄雌性Lewis大鼠随机分为去卵巢组(OVX)组和假手术组(Sham),每组各6只。OVX组行双侧卵巢切除术,假手术组仅显露双侧卵巢。术后6个月处死动物,取尾椎(L_(4-7))行Micro-CT分析及生物力学测试。结果去卵巢6个月后,OVX组大鼠体积骨密度(vBMD)和组织骨密度(tBMD)较Sham组显著降低,松质骨骨小梁的骨体积分数(BV/TV)和数目(TB.N)都明显低于Sham组,骨小粱表面积密度(BS/BV)、结构模拟指数(SMI)和间距(Tb.Sp)显著高于Sham组,差异有统计学意义。但2组间骨小梁厚度(Tb.Th)差异无统计学意义。生物力学测试结果表明,去势6个月后,OVX组大鼠骨质生物力学性能显著下降。骨小梁力学性能与骨小梁体积分数(Adjusted R~2=0.750和数目(Adjusted R~2=0.861)呈正线性相关,而与结构模拟指数(Adjusted R~2=0.716)和骨小梁间距(Adjusted R~2=0.830)呈负线性相关。结论松质骨骨小梁微观结构的改变可影响骨质的生物力学性能,二者之间具有一定的线性关系。     

Dose-dependent effects of tamoxifen on long bones in growing rats: influence of ovarian status

Tamoxifen is a nonsteroidal antiestrogen which has been reported by various investigators to have estrogen agonist and antagonist effects on rat bone. These different interpretations may be due to differences in the ovarian status, estrogen levels, and/or tamoxifen levels of the rats. To address this issue, a dose response was determined for the effects of tamoxifen on bone histomorphometry in intact female and ovariectomized (OVX) rats. The results were compared with those obtained after treatment of OVX rats with estrogen alone or a combination of estrogen and tamoxifen. OVX resulted in increases in growth rate (weight gain) and periosteal bone formation rate and decreases in uterine weight and cancellous bone fractional volume (BV/TV). Treatment of OVX rats with estrogen resulted in dose-dependent decreases in growth rate and periosteal bone formation rate as well as dose-dependent increases in uterine weight and BV/TV. Similarly, tamoxifen treatment resulted in dose-dependent decreases in overall growth rate and periosteal bone formation rate in both OVX and intact rats. Tamoxifen treatment prevented the decrease in BV/TV after OVX, although the highest dose of tamoxifen resulted in a small decrease in BV/TV in intact female rats. In contrast to estrogen, tamoxifen treatment prevented the increase in uterine weight in intact female rats as well as the decrease in uterine weight in OVX rats. Tamoxifen treatment did not alter the effects of 17 beta-estradiol on the periosteal bone formation rate in OVX rats, but reduced the increase in BV/TV to values similar to those in intact rats. These results are consistent with tamoxifen behaving as a partial estrogen agonist on rat bone.     

Sevelamer restores bone volume and improves bone microarchitecture and strength in aged ovariectomized rats

Sevelamer hydrochloride, a noncalcium phosphate binder, has been shown to reduce coronary artery and aortic calcification, and to improve trabecular bone mineral density in hemodialysis patients with chronic kidney disease. Here, we examined whether sevelamer given orally for 12 wk with normal food could restore bone volume (BV) and strength in aged ovariectomized (OVX) rats starting at 4 wk after OVX. Dual-energy x-ray absorptiometry, microcomputerized tomography, and bone histomorphometry analyses showed that OVX animals receiving sevelamer had increased trabecular BV (51%), trabecular number (43%), trabecular thickness (9%), cortical thickness (16%), mineral apposition rate (103%), bone formation rate (25%), and enhanced cortical and trabecular bone mechanical strength as compared with OVX rats. Sevelamer decreased collagen C telopeptide, increased osteocalcin levels, and decreased phosphate and magnesium levels without affecting calcium levels in the blood. Although sevelamer was not absorbed systemically, it stimulated osteoblast differentiation in BM-derived mesenchymal stem cell cultures, as evaluated by alkaline phosphatase positive colony-forming units, and inhibited recombinant human soluble receptor activator of nuclear factor-kappaB ligand-induced osteoclast differentiation, as evaluated by tartrate-resistant acid phosphatase positive cells in bone mineral-hematopoietic stem cell cultures. Surface enhanced laser desorption/ionization time-of-flight mass spectrometry analysis revealed that 69 proteins were differently expressed after OVX, of which 30% (20 of 69) were reversed to sham activity after sevelamer intake. PTH, fibroblast growth factor-23, and cytokine profile in serum were not significantly changed. Together, these results suggest that sevelamer in food increases the BV and improves biomechanical properties of bone in OVX rats.     

Parathyroid hormone induces formation of new cancellous bone with substantial mechanical strength at a site where it had disappeared in old rats

OBJECTIVE: The present study addresses the question--can PTH induce formation of trabeculae in areas where cancellous bone has disappeared? Two-year-old male rats were chosen, because in this aged animal model the distal femurs have almost no cancellous bone, and the marrow cavity has reached a substantial dimension. DESIGN: The rats were injected for 56 days with either PTH(1-34), 15 nmol/kg/day (62.5 microg/kg/day), or vehicle. METHODS: Transverse specimens, 2-mm high, were cut from the distal femoral metaphysis. Marrow cavity diameters and cancellous bone trabeculae were analysed by a micro-computerized tomography scanner. The cancellous bone within the cortical and endocortical rim of each specimen was submitted to a biomechanical compression test. Furthermore, the cancellous bone was studied by dynamic tetracycline labelling and histomorphometry. RESULTS: In the vehicle-injected group the trabecular bone volume was 0% (0-1.4), median (range). All PTH-injected rats had trabeculae in the distal metaphysis and the trabecular bone volume (6.7% (2.3-12.0)) was markedly increased (P<0.003). The median trabecular thickness was increased (P<0.003) in the PTH-injected rats (118 microm (104-125)) compared with the vehicle group (0 microm (0-71)). The compressive stress was increased (P<0.003) in the PTH-injected group (0.7 MPa (0.1-2.1)) compared with the vehicle-injected group (0 MPa (0-0.4)). The histomorphometry revealed that only 3 animals of the 10 in the vehicle-injected group had trabeculae in the distal femoral metaphysis. All PTH-injected animals (12 of 12) had continuous trabecular bone network in the marrow cavity. CONCLUSION: Intermittent PTH treatment induced marked formation of new cancellous bone trabeculae with substantial mechanical strength, at a site where it had disappeared in old rats.     

雄性ApoE基因敲除小鼠不同时期骨密度和骨微结构的改变

目的 观察ApoE基因敲除(ApoE-/-)小鼠的骨微结构、骨密度、骨矿含量(BMC)的变化,探讨ApoE在骨重建中的作用.方法 15、28和40周龄雄性ApoE-/-纯合子小鼠以及同性别、同周龄的野生型小鼠共48只,应用显微CT测定小鼠右侧股骨远端松质骨和皮质骨的骨微结构参数,双能X线骨密度仪(DXA)测定左侧股骨骨密度.并分析骨微结构、骨密度、BMC相关性.结果 与野生鼠相比,不同时期ApoE-/-鼠的股骨松质骨体积骨密度(vBMD)、组织骨密度、BMC、骨体积分数(BV/TV)、骨小梁数量(Tb.N)、骨小梁厚度(Tb.Th)明显增加(P<0.05),骨面积分数(BS/BV)、骨小梁间隔(Tb.SP)和结构模型指数明显减低(P<0.05).股骨皮质骨内径周长、皮质骨外径周长、皮质骨面积、骨髓腔面积、截面总面积和截面惯性矩增加,而皮质骨骨密度、皮质骨BMC和皮质骨厚度变化不明显.DXA测定显示28周龄ApoE-/-鼠的总体骨密度明显高于野生型鼠(P<0.05),15和40周龄ApoE-/-鼠总体骨密度与对照组相比,无统计学差异.28周龄ApoE-/-鼠vBMD与BMC、BV/TV、Tb.Th、BS/BV和皮质骨BMC明显相关,相关系数分别为0.955、0.944、0.834、0.923和0.903,而与其他参数不相关.结论 ApoE-/-鼠表现出骨量增加,提示ApoE在骨重建中起重要作用.     

仙灵骨葆对去势大鼠骨量和生物力学性能的影响

目的探讨仙灵骨葆对骨质疏松(OP)大鼠骨量、骨代谢和生物力学性能的影响。方法 3月龄雌性SD大鼠24只分为3组,每组8只:正常对照组(N)、卵巢切除组(OVX)、卵巢切除+仙灵骨葆治疗组(XLGB)。除N组外,其余两组行卵巢切除术,6 w后XLGB组给予药物干预:250 mg.kg-1.d-1,OVX组给予等量生理盐水,8 w后处死所有大鼠。留取尿液、血清检测血PINP值、尿DPYD/Cr、NTX/Cr值。取左侧股骨行骨密度测定,取左侧胫骨制备硬组织不脱钙切片,备行骨组织形态计量学检测,取右侧股骨行三点弯曲试验,检测其最大载荷。结果 OVX组血PINP、尿DPYD/Cr、尿NTX/Cr值显著高于N组,XLGB能显著降低血PINP、尿DPYD/Cr、尿NTX/Cr值,但仍显著高于N组。OVX组股骨全长及近、中、远三段骨密度均显著低于N组,XLGB组近、远端骨密度显著高于OVX组。BV/TV在OVX组显著低于N组,XLGB组显著高于OVX组;OVX、XLGB组骨吸收指标Oc.N、Er.Pm均显著高于N组,XLGB组Oc.N、Er.Pm显著低于OVX组,BFR/BV显著高于OVX组。最大载荷三组之间无显著差别。结论仙灵骨葆灌胃可抑制卵巢切除大鼠骨量丢失,其机制与促进骨形成、抑制骨吸收,降低骨转换水平,进而维持骨量及微观结构有关。     

甲状旁腺素1-34对骨质疏松大鼠治疗作用的实验研究

目的探讨甲状旁腺素134(hPTH134)对骨质疏松的治疗作用以及与血钙、磷、维生素D代谢和生长因子的关系。方法用摘除大鼠双侧卵巢的方式制备骨质疏松模型(OVX),实验动物分为4个组:模型对照组(OVX组,摘除大鼠双侧卵巢不作任何处理);hPTH134治疗组(PTH组,摘除大鼠双侧卵巢12w后用hPTH134治疗8w);盐酸雷洛昔芬治疗组(摘除大鼠双侧卵巢12w后用雷洛昔芬治疗8w);假手术组(Sham组,仅切除卵巢周围的脂肪组织约3g,术后12w纳入实验)。应用HOLOGIC第4代双能X线4500W骨密度仪测大鼠腰椎、股骨上段骨密度值(BMD);以骨形态计量学测股骨骨小梁面积、矿化沉积率;用ELISA法测定血清IGF1水平和血清25OHVitD浓度以及血淋巴细胞VitD受体(VDR)含量。结果hPTH134治疗组、盐酸雷洛昔芬治疗组均较OVX组腰椎、股骨上段骨密度增高,组间比较差异有显著性(P<0.01)。hPTH134治疗组较盐酸雷洛昔芬治疗组股骨上段骨密度增高,两组之间差异有显著性(P<0.01)。hPTH134治疗组骨小梁面积明显增加、矿化沉积率增高。hPTH134治疗组、盐酸雷洛昔芬治疗组血清IGF1浓度值、血清25OHVitD浓度值升高,与OVX组比较差异有显著性(P<0.01)。各组血淋巴细胞VDR含量无明显变化,与OVX组比较差异无显著性(P>0.05)。结论hPTH134能够预防腰椎、股骨上段骨密度丢失,使骨小梁面积明显增加、矿化沉积率增高并且血清IGF1及血清25OHVitD浓度值升高,但对VDR含量无明显作用。     

Cancellous Bone Volume Is an Indicator for Trabecular Bone Connectivity in Dialysis Patients

Background and objectives: A new assessment system for bone histology, termed the turnover-mineralization-volume system, is advocated for patients with chronic kidney disease-related mineral and bone disorder. The system measures cancellous bone volume (BV/TV) as a third major evaluation axis; however, the physiologic significance of BV/TV remains unclear.Design, setting, participants, & measurements: Conventional bone histomorphometry was performed in 75 iliac bone samples obtained from dialysis patients. In 47 of the 75 samples, the remaining samples were subjected to direct microfocus x-ray computed tomographic observation. Quantitative morphologic examinations, including micro-bone mineral densitometry, and marrow space star volume, Euler number, and node-strut analyses, were performed in the virtual three-dimensional space reconstructed from the microfocus x-ray computed tomographic images.Results: The levels of BV/TV were comparable in each of the conventional bone histomorphometric criteria. No significant correlations were found between BV/TV and other parameters. Two- and three-dimensional BV/TVs were significantly correlated with cancellous bone mass but not with cortical bone thickness or cortical bone mass. Two- and three-dimensional BV/TVs were significantly correlated with trabecular bone connectivity as determined by marrow space star volume, Euler number, and node-strut analyses.Conclusions: In dialysis patients, BV/TV is not dependent on bone turnover or bone mineralization. BV/TV is unlikely to indicate the balance between bone formation and bone resorption. Instead, it reflects trabecular bone connectivity, and improved trabecular bone connectivity is physiologically beneficial in terms of bone quality. The turnover-mineralization-volume system offers an advantage over the conventional system for the assessment of bone quality.Chronic kidney disease (CKD) is associated with various forms of metabolic bone disorders (1), which are accompanied by mineral and parathyroid metabolic abnormalities. These abnormalities are considered to be symptoms of a systemic syndrome called CKD-related mineral and bone disorder (CKD-MBD) (2).The current gold standard for assessing bone status in CKD-MBD is bone histology (3). Bone histology is conventionally classified into five categories on the basis of tetracycline labeling-dependent bone histomorphometric findings. In this conventional classification, the histologic findings are classified according to two major assessment criteria: bone turnover and bone mineralization (4). However, the Kidney Disease: Improving Global Outcomes recently advocated the addition of cancellous bone volume (BV/TV) as a third major evaluation criterion for bone histology in CKD-MBD patients. The concept of this system, called turnover-mineralization-volume (TMV) classification (2,5), has become widely recognized.The Kidney Disease: Improving Global Outcomes considers BV/TV to be the result of a balance between bone formation and bone resorption. However, the target for bone histomorphometric analysis is currently confined to cancellous bone area in most cases. Therefore, BV/TV actually indicates the balance between cancellous bone formation and cancellous bone resorption, which may not be identical to the balance between bone formation and bone resorption. The significance of knowing the balance between cancellous bone formation and cancellous bone resorption remains unknown.Thus, the justification of the use of BV/TV in the TMV system has not yet been demonstrated. First, it has not been confirmed whether BV/TV is independent of bone turnover and bone mineralization. If significant associations were found between these factors, the significance of BV/TV as an evaluation criterion would be limited.Moreover, the reason why BV/TV should be included in this classification has not been fully explained. It must be clarified whether BV/TV can theoretically enhance the balance between bone formation and bone resorption. It is unknown whether BV/TV reflects cortical bone mass, which is the major determinant of bone strength. Other factors that affect bone strength are referred to as bone quality (6), which includes the chemical and structural properties. In terms of chemical properties, bone turnover and bone mineralization can be assessed by conventional bone histomorphometry. However, it is unknown whether BV/TV is associated with the structural properties of bone quality. The validation of the TMV system in terms of these aspects has not yet been performed.On the basis of this background, we performed three-dimensional quantitative morphologic analyses of biopsied iliac bone samples obtained from CKD stage 5D (CKD5D) patients. We performed microfocus computed tomography (MCT) and novel three-dimensional image analysis (7–9). The aims of this study were (1) to confirm whether BV/TV, a new assessment criterion applied to the TMV system, is independent of bone turnover and bone mineralization, and (2) to determine whether and/or how BV/TV could be used to predict bone strength.     

Daily treatment with human recombinant parathyroid hormone-(1-34), LY333334, for 1 year increases bone mass in ovariectomized monkeys.

PTH stimulates bone formation to increase bone mass and strength in rats and humans. The aim of this study was to determine the skeletal effects of recombinant human PTH-(1-34) [rhPTH-(1-34)] in monkeys, as monkey bone remodeling and structure are similar to those in human bone. Adult female cynomolgus monkeys were divided into sham-vehicle (n = 21), ovariectomized (OVX)-vehicle (n = 20), and OVX groups given daily s.c. injections of rhPTH-(1-34) at 1 (n = 39) or 5 (n = 41) microg/kg for 12 months. Whole body bone mineral content was measured, as was bone mineral density (BMD) in the spine, proximal tibia, midshaft radius, and distal radius. Serum and urine samples were also analyzed. rhPTH-(1-34) treatment did not influence serum ionized Ca levels or urinary Ca excretion, but depressed endogenous PTH while increasing serum calcitriol levels. Compared to that in the OVX group, the higher dose of rhPTH-(1-34) increased spine BMD by 14.3%, whole body bone mineral content by 8.6%, and proximal tibia BMD by 10.8%. Subregion analyses suggested that the anabolic effect of rhPTH-(1-34) on the proximal tibia was primarily in cancellous bone. Similar, but less dramatic, effects on BMD were observed with the lower dose of rhPTH-(1-34). Daily s.c. rhPTH-(1-34) treatment for 1 yr increases BMD in ovariectomized monkeys without inducing sustained hypercalcemia or hypercalciuria.     

Combination treatment with pioglitazone and fenofibrate attenuates pioglitazone-mediated acceleration of bone loss in ovariectomized rats

Peroxisome proliferator-activated receptor (PPAR) γ agonists, such as pioglitazone (Pio), improve glycemia and lipid profile but are associated with bone loss and fracture risk. Data regarding bone effects of PPARα agonists (including fenofibrate (Feno)) are limited, although animal studies suggest that Feno may increase bone mass. This study investigated the effects of a 13-week oral combination treatment with Pio (10?mg/kg per day)+Feno (25?mg/kg per day) on body composition and bone mass parameters compared with Pio or Feno alone in adult ovariectomized (OVX) rats, with a 4-week bone depletion period, followed by a 6-week treatment-free period. Treatment of OVX rats with Pio+Feno resulted in ～50% lower fat mass gain compared with Pio treatment alone. Combination treatment with Pio+Feno partially prevented Pio-induced loss of bone mineral content (～45%) and bone mineral density (BMD; ～60%) at the lumbar spine. Similar effects of treatments were observed at the femur, most notably at sites rich in trabecular bone. At the proximal tibial metaphysis, concomitant treatment with Pio+Feno prevented Pio exacerbation of ovariectomy-induced loss of trabecular bone, resulting in BMD values in the Pio+Feno group comparable to OVX controls. Discontinuation of Pio or Feno treatment of OVX rats was associated with partial reversal of effects on bone loss or bone mass gain, respectively, while values in the Pio+Feno group remained comparable to OVX controls. These data suggest that concurrent/dual agonism of PPARγ and PPARα may reduce the negative effects of PPARγ agonism on bone mass.     

Decreased bone strength in HLA-B27 transgenic rat model of spondyloarthropathy

OBJECTIVE: To investigate the nature of osteopenia/osteoporosis in spondyloarthropathy, an inflammatory disorder, using the HLA-B27 transgenic rat model. METHODS: HLA-B27 transgenic rats were housed individually and sacrificed at the peak of their disease (8-month-old). The spine and femurs were removed and stored in saline at -20 degrees C until analysis. The bone structure and strength were determined using a micro-computed tomography (micro-CT) device (Scanco Medical) and mechanical testing (Instron 5543). Vertebral bodies and femurs were scanned to determine trabecular structural properties in terms of bone volume (BV/TV), trabecular thickness, and spacing. After scanning, the mid-shaft femurs were subjected to a 3-point bending test (along anterior-posterior direction), the femoral necks were tested in bending, and the vertebral bodies (L4) were tested in compression. Structural (ultimate/yield load, stiffness) and apparent material (ultimate/yield stress, modulus) strength parameters were then determined. RESULTS: The majority of the bone structural and strength parameters were significantly lower (P < 0.05) in the HLA-B27 transgenic rats as compared with control littermates. Micro-CT data suggested that the transgenic animals had lower BV/TV and trabecular thickness in their vertebral bodies. The poor trabecular structure observed in HLA-B27 rats is also indicative of the poor biomechanical strength properties in the vertebral bodies as well. CONCLUSION: The HLA-B27 transgenic rats develop bone fragility similar to that seen in spondyloarthropathy and may be an important model for the study of osteoporosis in spondyloarthropathy.     

柚皮苷联合运动对去势大鼠骨量和骨强度的影响

目的观察柚皮苷（NG）联合中强度跑台运动对去势大鼠骨质疏松模型的治疗效果。方法2月龄雌性SD大鼠80只,用随机数字法分为假手术组（SHAM）、去势组（OVX）、去势＋不同浓度（40、100、200 mg/kg）柚皮苷组（OVX＋NG）、去势＋跑台＋柚皮苷组（OVX＋EX＋NG）、去势＋跑台组（OVX＋EX）、雌激素组（OVX＋E2）,每组10只。大鼠切除卵巢2个月后开始给药,给药60 d后观察各组大鼠股骨骨密度（BMD）,Micro-CT参数,血清生化指标及及股骨力学性能与组织学改变。结果柚皮苷与跑台运动干预60 d后,OVX＋EX＋NG组大鼠股骨颈力学强度、股骨BMD、BV/TV、Tb.N、Tb.Th等均高于单纯去势组（P〈0.05）,OVX＋EX＋NG组治疗效果与柚皮苷浓度呈正相关,以200 mg/kg柚皮苷效果最佳;200 mg/kg柚皮苷联合中强度跑台运动可进一步提高治疗效果。OVX＋NG组大鼠血清骨钙素升高,Ⅰ型胶原C端肽（CTX-1）降低;OVX＋EX组大鼠骨钙素与CTX-1均降低;OVX＋EX＋NG组大鼠骨钙素水平与柚皮苷组（200 mg/kg）无差异,但高于OVX＋EX。OVX＋EX＋NG组CTX-1水平低于单纯柚皮苷组和单纯跑台组（P〈0.05）。结论柚皮苷联合中强度跑台运动可提高去势大鼠股骨BMD,增加骨小梁数目,改善骨代谢指标,提高股骨力学性能。     

Prolonged low-dose infusion of human parathyroid hormone does not increase femoral cancellous bone volume in ovariectomized rats.

OBJECTIVE: Daily injections of human parathyroid hormone (hPTH) increase bone volume in various animal species and in osteoporotic women. For hPTH to be widely accepted as an anabolic therapy for treating postmenopausal osteoporosis alternative delivery options need to be explored to replace the need for daily patient subcutaneous self-injection. Among these are inhalation, oral delivery and the use of programmable implanted minipumps to deliver the peptide. While infusion of high doses of PTH causes bone loss and hypercalcemia, no studies have assessed the effects of prolonged infusion of low doses of PTH on bone growth. DESIGN AND METHODS: [Leu(27)]-cyclo(Glu(22)-Lys(26))-hPTH-(1--31)NH(2) was delivered by Alzet minipumps to ovariectomized rats for 6 weeks after which histomorphometric indices (cancellous bone volume, trabecular thickness, mean trabecular number) of bone formation were measured in distal femurs. RESULTS: Infusing low doses (0.05 and 0.1 nmole/100g body weight/day) of the hPTH analog, [Leu(27)]-cyclo(Glu(22)-Lys(26))-hPTH-(1--31)NH(2), for 6 weeks does not prevent the ovariectomy-induced loss of rat femoral cancellous bone volume, trabecular thickness or trabecular number. CONCLUSION: These results support the absolute requirement of daily injections for the osteogenic action of hPTH on bone.     

旋转中心偏移对显微CT松质骨定量分析的影响

目的观察旋转中心微小偏移对显微CT测量参数的影响。方法20只7月龄sD大鼠随机分为去卵巢组（OVX）和假手术组（SHAM）。手术后3周处死,应用显微cT扫描胫骨近干骺端。手动校正以获取每次扫描的最佳旋转中心,分析各旋转中心在偏移±0．5、±1．0、±1．5和±2．0像素条件下的密度及微结构参数。结果一般线性模型分析结果显示OVX组与SHAM组比较,表观骨密度、组织骨密度、骨体积分数、骨小梁数量和联接密度明显下降,骨小梁间隔明显增宽（P〈0．05）。组织骨密度、各向异性度、骨小梁面积密度和联接密度随旋转中心的偏移下降,骨体积分数和骨小梁厚度随偏移幅度的加大逐渐升高。旋转中心偏移±1．5像素内,对组织骨密度、骨体积分数、各向异性度和联接密度的测量无影响。而骨小梁厚度和骨小梁面积密度在旋转中心偏移±1．0像素内影响较小。OVX组与SHAM组各参数随旋转中心偏移的变化趋势基本一致。各参数随旋转中心偏移服从二次回归方程趋势。通过二次回归方程拟合,可以获得实际旋转中心。以该中心获取的图像质量高,并能确保定量分析数据的准确。实际旋转中心与人为校正的最佳旋转中心之间存在微小差异。结论旋转中心的微小偏移对表观骨密度、结构模型指数、骨小梁间隔和数量的测量无明显影响。组织骨密度、骨小梁厚度、骨小梁面积密度、骨体积分数、各向异性度和联接密度受旋转中心偏移影响较大。通过二次曲线方程拟合能找到正确的旋转中心,该中心与人为校正获取的最佳旋转中心存在一定误差。     

Bone histomorphometry in 50 normal tunisian subjects

Summary Quantitative bone histomorphometry was done on undecalcified sections of iliac crest bone specimens obtained at autopsy from 50 normal subjects (24 males and 26 females). The following parameters were measured: cortical thickness (Ct.Th), trabecular bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), osteoid volume (OV/BV), osteoid surfaces (OS/BS), osteoid thickness (O.Th) and eroded surfaces (ES/BS). There was a significant age-related decrease in BV/TV in both sexes which followed a x³ polynomial regression. A significant decrease of Tb.Th was noted in males after the fifth decade. In males, bone loss was 1.5% per decade, but in females it was 0.36% before menopausal period and 2% after. Other parameters were unrelated to age and sex.     

The femoral distal epiphysis of ovariectomized rats as a site for studies on osteoporosis: structural and mechanical evaluations

OBJECTIVE: To investigate in detail the mechanical and structural characteristics of cancellous bone from the femoral distal epiphysis of normal and ovariectomized rats, and to provide reference values in order to improve experimental research on osteoporosis by characterising an alternative and complementary anatomic site. METHODS: 40 female Sprague-Dawley rats (10 months old) were randomly divided into 4 groups of 10 each: baseline, ovariectomized (Ovx), sham-operated (Sham-Ovx) and sham-aged (Sham-Aged). Baseline animals were sacrificed at the beginning of the study. Ovx and Sham-Ovx animals were sacrificed 16 weeks after surgery, whereas Shamaged rats were killed when aged 14 months. Femurs were excised and densitometric, ultrasonographic, mechanical and histomorphometric analyses were performed. RESULTS: When comparing the Ovx group with the others, ultrasonographic and densitometric measurements showed significant decreases (p < 0.0005) amounting to 3-5% in the amplitude dependent speed of sound (AD-SOS) and 13-20% in the BMD, respectively. Significant decreases were also seen in the femoral condyle Max. Load (28-31%; p < 0.0005) and Elastic Modulus (19-25%; p < 0.005) in the Ovx group in comparison with the Sham-Ovx and Sham-Aged groups. Histomorphometric analysis showed a significant cancellous bone loss (p < 0.0005). Densitometric (p < 0.01), histomorphometric (p < 0.01) and mechanical (p < 0.05) parameters were correlated with AD-SOS. Among the histomorphometric parameters, stepwise regression analysis showed that the trabecular bone volume (BV/TV) and Max.Load correctly predicted AD-SOS (p < 0.0005) and BMD (p < 0.0005). CONCLUSION: The data from this study characterize osteopenia occurring in the rat distalfemur 16 weeks after ovariectomy and provide methodology and reference values forfurther investigations on osteoporosis and bone-implant osteointegration in osteopenic bone.