Time-dependent changes in biochemical bone markers and serum cholesterol in ovariectomized rats: Effects of raloxifene HCl, tamoxifen, estrogen, and alendronate

Bone loss associated with postmenopausal osteoporosis can be reduced by treatment with antiresorptive agents such as estrogen or bisphosphonates. Whereas bisphosphonates primarily affect bone loss, estrogens have an advantage of also lowering serum cholesterol levels, although they have a detrimental effect in the uterus. Recently, raloxifene HCl, a selective estrogen receptor modulator (SERM), has been shown to decrease both bone loss and cholesterol levels without the negative uterine effects. These antiresorptive agents reduce bone turnover, which can be evaluated by measuring bone turnover markers. To compare the effects of estrogen, two SERMs (raloxifene HCl and tamoxifen), and alendronate, a bisphosphonate that inhibits bone loss by an estrogen-independent pathway, on metabolic bone markers and cholesterol levels, rats were ovariectomized 2 weeks prior to 3 weeks of daily oral treatment with raloxifene HCl (3 mg/kg), ethynyl estradiol (0.1 mg/kg), tamoxifen (3 mg/kg), or alendronate (3 mg/kg). Raloxifene HCl, tamoxifen, and ethynyl estradiol reduced serum cholesterol to levels below control values within 4 days after initiation of treatment, whereas alendronate had no effect. After 3 weeks of treatment, serum cholesterol values in ethynyl estradiol treated animals, although still below the control value, had risen 6.4-fold; raloxifene HCl and tamoxifen values rose by only 1.4–1.5-fold. Therefore, compared with estrogen, SERMs may have a longer-term suppressive effect on serum cholesterol. At 4 days of treatment, ovariectomized rats had a 1.4-fold increase in serum osteocalcin level compared with controls. Ethynyl estradiol lowered this level within 1 week of treatment by 18%, with a more pronounced reduction of 34% at 3 weeks. In contrast, raloxifene HCl, tamoxifen, or alendronate had very little effect after the first week (6% to 13% reduction), although there was an 18% to 25% reduction by 3 weeks. Urinary pyridinoline levels, elevated 1.4-fold in the ovariectomized rat compared with controls 2 weeks after surgery, were reduced to control values after 2 weeks of treatment with raloxifene HCl, ethynyl estradiol, tamoxifen, or alendronate. These data support the concept that estrogen, raloxifene HCI, tamoxifen, and alendronate inhibit bone loss in the ovariectomized animal by reducing bone resorption. The results also indicate that for treatment of postmenopausal osteoporosis, raloxifene HCl may have an advantage over the other antiresorptives studied in having both non-uterotrophic and hypocholesterolemic effects in addition to its ability to inhibit bone resorption.     

雷洛昔芬上调卵巢切除大鼠腰椎护骨素mRNA的表达

目的建立绝经后骨质疏松（postmenopausal osteoporosis，PMOP）的大鼠模型，研究雷洛昔芬（raloxifene，RLX）对卵巢切除大鼠腰椎组织中护骨素（OPG）基因mRNA表达水平的影响，探讨其治疗PMOP的作用机制。方法6月龄未交配健康雌性SD大鼠40只，随机分为假手术（SHAM）组，卵巢切除（OVX）组，OVX＋戊酸雌二醇（E2）组和OVX＋RLX组。灌胃13周后处死动物，第四腰椎行骨组织形态计量指标测定，第二腰椎采用RT-PCR方法，对OPGmRNA表达水平进行检测。结果OVX组大鼠较SHAM组骨小梁体积百分比（TBV％）显著下降；类骨质体积百分比（OSV％）明显升高（P〈0．05）；B和RLX组大鼠的TBV％明显升高，OSV％明显下降；OPGmRNA表达水平在OVX大鼠组织中下调，与SHAM组相比有显著性差异（P〈0．05），E2和RLX均可上调OVX大鼠骨组织OPGmRNA表达水平（P〈0．05）。结论实验成功制造了大鼠PMOP模型；E2和RLX均可抑制骨转换；PMOP的发生与OPG有关，RLX和E2一样，其抗骨吸收效应很可能是通过OPG介导的。     

The bisphosphonate, alendronate, prevents bone loss in ovariectomized baboons.

We examined the effect of the amino bisphosphonate alendronate, administered IV every 2 weeks at 0.05 and 0.25 mg/kg for 1 year, on bone loss and parameters related to bone metabolism in ovariectomized baboons. Relative to non-OVX animals, the OVX baboons experienced increased bone turnover, reflected in biochemical and histomorphometric measurements, and bone loss assessed by dual-beam absorptiometry in the lumbar spine, which was similar to changes observed in ovariectomized women. Alendronate treatment maintained all parameters of bone turnover at control (nonovariectomized) levels and prevented the bone loss in a dose-dependent manner. We concluded that ovariectomized baboons offer a suitable model for the bone changes observed in ovariectomized women and that these changes can be prevented by sustained administration of an appropriate dose of this aminobisphosphonate.     

Effect of alendronate and intermittent parathyroid hormone on implant fixation in ovariectomized rats

Background  Intermittent administration of parathyroid hormone (PTH) leads to bone formation by increasing osteoblast numbers and activity levels. Animal studies have shown that intermittent PTH administration increases implant fixation in normal rats. The purpose of this study was to analyze the osseous incorporation of an implant in osteoporotic rats while treating them with intermittent PTH (1–34) or alendronate. Methods  A total of 36 ovariectomized (OVX) Wistar rats were randomized into three groups. Polymethylmethacrylate cement rods were implanted in one tibia in each rat. The three groups received daily PTH (60 μg/kg body weight [BW]), alendronate (200 μg/kg BW), or saline (0.5 ml/kg BW). A sham-ovariectomized group (n = 12) was treated with saline. After 2 weeks, the area around the implants was analyzed by histomorphometry for bone volume density (BVD) and implant bone contact. Bone mineral density (BMD) was evaluated by dual-energy X-ray absorptiometry. Results  The BVD was higher in the specimens treated with PTH than in the other groups. PTH improved the BVD, BMD, and implant bone contact. Alendronate doubled the implant bone contact compared to the OVX and sham groups but did not improve BVD or BMD. Conclusions  These findings confirm that intermittent PTH enhances implant fixation in osteoporotic bone. The clinical significance of these findings is that application of intermittent PTH may be beneficial for early implant fixation in fractures, nonunions, and prosthetic replacements when bone density is decreased.     

Early period of fracture healing in ovariectomized rats

Objective. To evaluate the effect of osteoporosis on fracture healing through observing the hlstomorphological changes, bone mineral density of callus and expression and distribution of transforming growth factor beta 1 (TGF-β1 ), basic fibroblast growth factor (bFGF)and bone morphogenetic protein.2 (BMP-2) in ovariectomized rats. Methods. Sixty female Sprague-Dawley rats ( aged 12 weeks and weighing 235 g on average ) were randomly divided into an ovariectomized (OVX) group (n =30) anda sham-operated (SO) group ( n = 30). Ovariectomy was performed in the OVX rats and same incision was made in the SO rats. Three months later, fracture of femoral shaft was made on all the rats. Then they were killed at different time points. Callus formation was observed with histological and imethods. Results: A reduction in callus and bone mineral density in the healing femur and a decrease of osteoblasts expressing TGF-β1 near the bone trabecula were observed in the OVX rats 3-4 weeks after fracture.Histomorphological analysis revealed a higher content of soft callus in the OVX rats than that in the SO rats.Immunohistochemistry results showed that no remarkable difference in expression and distribution of BMP-2 and bFGF between the OVX and SO groups was found. Conclusions: Osteoporosis influences the quantity and quality of callus during the early period of fracture healing. The effect of osteoporosis on fracture healing has no relationship with the expression of BMP-2 or bFGF. The decreased expression of TGF-I31 in osteoblasts may cause a decrease in quality of facture healing after osteoporosis.     

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。     

Effect of alendronate in elderly patients after low trauma hip fracture repair

Summary

One year of once weekly alendronate, when given shortly after the surgical repair of a hip fracture, produces reductions in bone markers and increases proximal femoral bone density. The therapy was well tolerated.

Introduction

Hip fracture is the most devastating type of osteoporotic fracture and increases notably the risk of subsequent fractures. The aim of this paper was to evaluate the effects of 1 year therapy with a weekly dose of alendronate in the bone mineral density and bone markers in elderly patients after low trauma hip fracture repair.

Methods

Two hundred thirty-nine patients (81?±?7 years; 79.8% women) were randomized to be treated either with calcium (500 mg/daily) and vitamin D₃ (400 IU/daily; Ca–Vit D group) or with alendronate (ALN, 70 mg/week) plus calcium and vitamin D₃ (500 mg/daily and 400 IU/daily, respectively; ALN + Ca–Vit D group).

Results

One hundred forty-seven (61.5%) patients completed the trial. Alendronate increased proximal femoral bone mineral density (BMD) in the intention-to-treat analysis (mean difference (95% confidence interval); total hip 2.57% (0.67; 4.47); trochanteric 2.96% (0.71; 5.20), intertrochanteric 2.32% (0.36; 4.29)), but the differences were not significant in the BMD of the femoral neck (0.47%; (?2.03; 2.96) and the lumbar spine (0.69%; (?0.86; 2.23)). Bone turnover markers decreased during alendronate treatment.

Conclusion

The present study demonstrates for the first time the anti-resorptive efficacy of alendronate given immediately after surgical repair in an elderly population with recent hip fracture. This effect should positively affect the rate of subsequent fractures.     

Zoledronic acid enhances bone-implant osseointegration more than alendronate and strontium ranelate in ovariectomized rats

Summary

This study was designed to compare the effects of alendronate (ALN), strontium ranelate (SR), and zoledronic acid (ZOL) on bone-implant osseointegration in ovariectomized rats. Histological examination and biomechanical tests show that ZOL, ALN, and SR enhance bone-implant osseointegration; ALN and SR have similar effects, while ZOL enhances bone-implant osseointegration more than ALN and SR

Introduction

This study aims to compare the effects of ALN, SR, and ZOL on bone-implant osseointegration in ovariectomized rats.

Methods

Sixty female Sprague–Dawley rats were included in this study. Of them, 48 rats were ovariectomized (OVX) and assigned to four groups: OVX (OVX?+?Veh), ALN (OVX?+?ALN), SR (OVX?+?SR), and ZOL (OVX?+?ZOL). And another 12 rats were sham-operated as a control group (Sham). Four weeks after ovariectomy, HA-coated titanium implants were inserted into the tibias bilaterally in all rats. Then the rats in groups ALN, SR, and ZOL were systemically administrated with alendronate (7 mg/kg/week, orally), strontium ranelate (500 mg/kg/day, orally), or a single injection of zoledronic acid (0.1 mg/kg, iv), respectively. Twelve weeks after implantation, all rats were sacrificed to get the femurs and tibias. Histological examination and biomechanical tests were used to evaluate bone-implant osseointegration in all groups.

Results

ALN, SR, and ZOL significantly increased distal femoral BMD when compared with group OVX; ZOL increased BMD significantly more than ALN and SR (P?<?0.05). Significant increase of bone-to-implant contact and peri-implant bone fraction were observed in groups ALN, SR, and ZOL when compared with group OVX (P?<?0.05). Groups ALN and SR were inferior to groups ZOL and Sham (P?<?0.05) in bone-to-implant contact and peri-implant bone fraction. Similar results were found in biomechanical testing (max pushout force).

Conclusions

In rats losing bone rapidly after ovariectomy, systemic administration of ZOL, ALN, and SR causes better bone-implant osseointegration when compared to OVX; ALN and SR have similar positive effects on osseointegration, while ZOL, that was given in a dose with more positive BMD effect than that of ALN or SR, causes better osseointegration than either ALN or SR.     

Effects of combined elcatonin and alendronate treatment on the architecture and strength of bone in ovariectomized rats

We examined the combined effects of elcatonin (ECT) and alendronate (ALN) on bone mass, architecture, and strength in ovariectomized (OVX) rats. Fifty female Sprague Dawley rats, aged 13 weeks, were divided into Sham, OVX, OVX+ECT, OVX+ALN, and OVX+ECT+ALN groups (n = 10). Immediately after ovariectomy, ECT was administered at a dose of 15 units (U)/kg three times a week, and ALN was administered daily at a dose of 2.0 µg/kg, subcutaneously for 12 weeks. The three-dimensional architecture of the bone in the distal femoral metaphysis was analyzed using a microfocus X-ray computed tomography system (µCT), and bone strength was measured using a material-testing machine. Trabe-cular bone volume (BV/TV) and number (Tb.N) were significantly greater in the OVX+ECT and OVX+ALN groups than in the OVX group. In the OVX+ECT+ALN group, BV/TV and Tb.N were significantly greater when compared with those in the OVX+ECT and OVX+ALN groups. Trabecular thickness (Tb.Th) was significantly greater in the OVX+ECT+ALN group than in the OVX+ALN group. With regard to bone strength, the compression strength in the femoral metaphysis was significantly lower in the OVX group than in the Sham group. The reduction of compression strength was slightly lower in the OVX+ECT and OVX+ALN groups. In the OVX+ECT+ALN group, the compression strength in the femoral metaphysis significantly increased when compared with the OVX and OVX+ECT groups. These results suggest that the combined treatment of ECT and ALN does not alter the individual effects of each drug and that it exerts an additive effect on trabecular architecture and bone strength in OVX rats.     

Additive protective effects of estrogen and androgen treatment on trabecular bone in ovariectomized rats.

Both ER and AR activation regulates trabecular bone mass. We show that combined estrogen and androgen treatment results in additive protection of trabecular bone in OVX rats. This may in part be attributable to the effect of AR activation to attenuate the inhibitory effect of ER activation on bone formation. INTRODUCTION: Sex steroids are important regulators of trabecular bone mass. Both estrogen receptor (ER) and androgen receptor (AR) activation results in increased trabecular bone mass. The aim of this study was to investigate if combined estrogen and androgen treatment might be beneficial in the treatment of trabecular bone loss. MATERIALS AND METHODS: Twelve-week-old female rats were ovariectomized (OVX) and treated with vehicle (V), 17beta-estradiol (E2; ER activation), dihydrotestosterone (DHT; AR activation), or the combination (E2 + DHT) for 6 weeks. The skeletal phenotype was analyzed by pQCT, microCT, histomorphometry of growth plates, and serum levels of biochemical bone markers. RESULTS: Both E2 (+121% over V) and DHT (+34%) preserved the trabecular volumetric BMD (tvBMD) in OVX rats. The effect of E2 and DHT on tvBMD was additive, resulting in a 182% increase over V in the rats given E2 + DHT. MicroCT analyses of the trabecular bone microstructure revealed that the effect of E2 and DHT was additive on the number of trabeculae. E2 treatment reduced serum markers of both bone resorption (collagen C-terminal telopeptide) and bone formation (osteocalcin), indicating reduced bone turnover. Addition of DHT to E2 treatment did not modulate the effects of E2 on the marker of bone resorption, whereas it attenuated the inhibitory effect of E2 on the bone formation marker, which might explain the additive protective effect of E2 and DHT on trabecular bone mass. In contrast, DHT partially counteracted the suppressive effect of E2 on longitudinal bone growth and the E2-induced alterations in growth plate morphology. CONCLUSIONS: These findings show that combined estrogen and androgen treatment results in additive protective effects on trabecular bone in OVX rats. Our data suggest that a combined treatment with selective ER and AR modulators might be beneficial in the treatment of osteoporosis.     

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.

A new selective estrogen receptor modulator, CHF 4227.01, preserves bone mass and microarchitecture in ovariectomized rats.

A new SERM, CHF 4227.01, given to 6-month-old female rats immediately after ovariectomy, preserved bone mass and bone microarchitecture without affecting uterus weight. It also decreased serum cholesterol and fat mass in estrogen-deficient rats. INTRODUCTION: We tested the effect of a new benzopyran derivative, CHF 4227.01, with selective estrogen receptor modulator (SERM) activity on bone mass and biomechanics in ovariectomized (OVX) female rats in comparison with 17alpha-ethinylestradiol (EST), raloxifene (RLX), and lasofoxifene (LFX). MATERIALS AND METHODS: Four doses of CHF 4227.01 (0.001, 0.01, 0.1, and 1 mg/kg body weight [bw]/day) were administered in OVX animals daily by gavage 5 days/week for 4 months. EST was administered at a dose of 0.1 mg/kg bw/day, whereas RLX and LSX were administered at doses of 1 and 0.1 mg/kg bw/day, respectively, by gavage. In one group (Sham), rats were operated but the ovaries not removed; another OVX group was treated only with placebo. RESULTS AND CONCLUSIONS: Treatment with CHF 4227.01 (1.0 and 0.1 mg/kg bw), EST (0.1 mg/kg bw), LFX (0.1 mg/kg bw), or RLX (1.0 mg/kg bw) prevented bone loss on the lumbar spine and the proximal femur assessed in vivo by DXA. Volumetric BMD obtained by pQCT ex vivo confirmed protection from bone loss in the spine and proximal femur among rats treated with CHF 4227.01. This effect was associated with strong inhibition of bone resorption both histologically and biochemically. Furthermore, CHF 4227.01 preserved trabecular microarchitecture, analyzed by muCT, and maintained biomechanical indices of bone strength in the spine and proximal femur, effects also observed for RLX, whereas LSX was less protective of microarchitecture. CHF 4227.01 treatment did not affect uterine weight, prevented the increase in body weight and fat mass seen in OVX animals, and decreased serum cholesterol to below the average of intact animals. In conclusion, CHF 4227.01 exhibits a promising therapeutic and safety profile as a new SERM on both skeletal and extraskeletal outcomes.     

Skeletal effects of withdrawal of estrogen and diphosphonate treatment in ovariectomized rats

Summary The study was designed to determine the skeletal effects of withdrawal of estrogen and diphosphonate treatment in the estrogen-deplete state. Groups of ovariectomized (OVX) rats were treated with vehicle alone, estrogen, or the diphosphonates etidronate or risedronate for a 180-day period. A group of sham-operated control rats was treated for 180 days with vehicle alone. All treatments were then terminated, followed by sequential sacrifice of rats at 0, 35, 90, 180, and 360 days after withdrawal of treatment. The proximal tibia from each animal was processed undecalcified for quantitative bone histomorphometry. At the end of the treatment period, vehicle-treated OVX rats were characterized by cancellous osteopenia and increased bone turnover relative to vehicle-treated control rats. Treatment of OVX rats with estrogen or diphosphonates depressed bone turnover and protected against cancellous osteopenia. During the withdrawal period, OVX rats previously treated with estrogen exhibited rapid bone loss associated with increased bone turnover. The bone protective effect of the hormone in OVX rats was nearly completely lost by 90 days of withdrawal. In contrast, OVX rats maintained low levels of bone turnover and normal cancellous bone mass at 180 days of withdrawal from diphosphonate treatment. The results suggest that estrogen-deplete women who are withdrawn from estrogen replacement are at high risk for subsequent bone loss. They further suggest that widely spaced periods of intermittent diphosphonate treatment may be sufficient to prevent the development of osteopenia in postmenopausal and oophorectomized women.     

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.     

雌激素预防性给药对去卵巢大鼠骨和脏器的影响

目的采用双侧卵巢切除术建立绝经后骨质疏松(postmenopausal osteoporosis,PMOP)大鼠模型,探讨雌激素预防性给药对绝经后大鼠骨和脏器的影响。方法将SD大鼠分为假手术(sham-operated,Sham)组、去卵巢(ovariectomized,OVX)组、雌二醇组(β-estradiol-treated OVX,OVX/E2)组。术后第10 d开始皮下注射给药并称量大鼠体重,术后61 d处死大鼠,取脏器和骨,称量脏器重量,计算脏器指数。制备组织切片,进行HE染色。结果组织形态学观察表明,OVX组大鼠的股骨和胫骨均出现骨小梁断裂、间距变大、结构紊乱等骨质疏松症状,而OVX/E2组并未出现明显的发病症状。相较于Sham组,OVX组大鼠子宫内膜固有层中的子宫腺数目增多,腺腔增大,子宫黏膜上皮明显增厚,而OVX/E2组的大鼠子宫形态结构并未发生明显病变。大鼠体重和脏器指数分析表明,摘除卵巢不仅会引起大鼠术后早期的体重增加,还会导致大鼠肝、肺、肾和脾的脏器指数增加,而雌激素预防性给药能一定程度上缓解去卵巢手术引发的脏器指数的异常变化。结论适时进行一定剂量的雌激素给药能够较好地预防绝经后骨质疏松症的发生,为绝经后骨质疏松症的预防和治疗提供参考。     

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.     

雌激素对去卵巢大鼠脑黑质-纹状体多巴胺系统的影响

目的 :观察去卵巢 ( OVX)大鼠纹状体多巴胺 ( DA)神经递质的含量、释放及其受体活性的变化 ,并于体外进一步观察雌二醇对纹状体脑片释放 DA的作用特点。方法 :DA含量采用高效液相电化学检测器检测 ,其他采用同位素标记法。结果 :OVX鼠纹状体 DA含量明显低于正常组 ;纹状体脑片 DA释放显著减少 ;DA摄取未见改变 ;纹状体 DA受体活性在 OVX鼠是对照组的 2倍 ,在下丘脑无明显改变。体外观察到雌二醇对纹状体 DA释放作用的剂量 -效应曲线呈钟形。结论 :雌激素对脑内纹状体 DA功能有明显调节作用 ,并存在部位、剂量依赖性     

Immunohistochemical analysis of estrogen receptors in the urethra of sexually intact,ovariectomized, and estrogen-substituted ovariectomized sheep

Introduction and hypothesis

Urinary incontinence is prevalent in postmenopausal women and spayed dogs and is associated with decreased estrogen plasma concentrations. The objective of the study was to investigate the expression of estrogen receptors (ER) in the urethra of sexually intact, ovariectomized, and estrogen-substituted ovariectomized ewes.

Methods

Paraffin cross-sections from each urethral quarter were immunohistochemically analyzed. The reactivity of ER was semiquantitatively assessed employing an immunoreactive score (IRS).

Results

In contrast to ERβ, ERα was identified in all urethral compartments; the highest IRS was detected in the epithelium of the distal urethra. The immunoreactivity and distribution of ERα did not differ among groups. Highly significant differences in ERα concentrations were observed between consecutive urethral quarters in each group.

Conclusions

Neither ovariectomy nor ovariectomy and estrogen substitution seem to have a significant effect on overall urethral ERα concentration. The results demonstrate that the precise location of the investigated urethral part is crucial to the reliable evaluation or possible comparison of ERα concentrations.     

降钙素对卵巢切除大鼠股骨骨折愈合的影响

目的观察降钙素对卵巢切除大鼠股骨骨折愈合的作用，为临床上治疗骨质疏松性骨折提供实验依据。方法50只雌性、14周龄SD大鼠共分成5组，每组10只。分成假手术组（Sham，G1），双侧卵巢切除术组（OVX，G2），假手术＋骨折组（Sham＋F，G3），卵巢切除术＋骨折组（OVX＋F，G4），卵巢切除＋骨折＋降钙素药物组（OVX＋F＋CT，G5），骨折组大鼠均采用右股骨中段横行骨折，髓内针固定；降钙素采用皮下给药，隔日1次（16IU·kg^-1）。所有大鼠于术后4周杀死，取右侧股骨标本。然后，分别进行CR摄片、组织形态学观察，并应用双能X线骨密度仪（DEXA）测量右股骨整体、远段和中段骨密度以及BMP-2免疫组化观察，并应用病理图像分析仪对BMP-2免疫组化进行光密度测量。结果（1）OVX组与Sham组比较，BMD显著下降。（2）OVX＋F＋CT组与OVX＋F组比较：骨痂mBMD显著增高；BMP-2的表达无显著性差异。结论降钙素对OVX大鼠股骨骨折具有明显促进骨折愈合的作用，加速编织骨向板层骨的演变过程。