Effects of raloxifene, a selective estrogen receptor modulator, on bone turnover markers and serum sex steroid and lipid levels in elderly men.

Several lines of evidence implicate estrogen deficiency as a cause of bone loss in elderly men. Thus, in 50 elderly men (mean age +/- SD, 69.1 +/- 6.0 years), we performed a randomized blinded study to assess the effect of 6 months of treatment with 60 mg/day of raloxifene (a selective estrogen receptor modulator [SERM] that has an agonist effect on bone but is not feminizing) versus placebo on bone turnover markers. The mean changes in bone turnover markers, serum sex steroid, or lipid levels with treatment did not differ between groups. However, changes in urinary cross-linked N-telopeptide of type I collagen (NTX) excretion were related directly to the baseline serum estradiol level in the raloxifene (r = 0.57; p = 0.004) but not in the placebo-treated (r = 0.15; p = 0.485) men (p = 0.015 for the difference between groups). Moreover, the men in whom NTX excretion decreased after raloxifene treatment had significantly lower baseline estradiol levels (mean +/- SEM, 22 +/- 2 pg/ml) than the men in whom urinary NTX excretion didn't change or increased after raloxifene therapy (30 +/- 3 pg/ml; p = 0.03), and no such difference was found in the placebo group. Thus, raloxifene has no significant effect on bone turnover markers or lipid levels in elderly men. However, the association noted between baseline estradiol levels and the change in urine NTX excretion in the raloxifene-treated men suggests that a subset of men with low estradiol levels may respond to raloxifene or other SERMs, and further studies are needed to directly test this possibility.     

Raloxifene, estrogen, and alendronate affect the processes of fracture repair differently in ovariectomized rats.

We investigated the effects of inhibitors of bone resorption (estrogen, raloxifene, and alendronate) on the processes of fracture repair in ovariectomized (OVX) rats. One hundred forty female Sprague-Dawley rats at 3 months of age were either OVX or sham-operated and divided into five groups: sham control, OVX control, estrogen (17alpha-ethynyl estradiol [EE2], 0.1 mg/kg), raloxifene (Rlx, 1.0 mg/kg), and alendronate (Aln, 0.01 mg/kg) groups. Treatment began immediately after the surgery. Four weeks postovariectomy, prefracture controls were killed and bilateral osteotomies were performed on the femoral midshafts and fixed with intramedullary wires. Treatment was continued and fracture calluses were excised at 6 weeks and 16 weeks postfracture for evaluation by X-ray radiography, quantitative computed tomography (QCT,) biomechanical testing, and histomorphometry. At 6 weeks postfracture, Aln and OVX had larger calluses than other groups. Sham and OVX had higher ultimate load than EE2 and Rlx, with Aln not different from either control. Aln calluses also contained more mineral (bone mineral content [BMC]) than all other groups. By 16 weeks postfracture, OVX calluses were smaller than at 6 weeks and the dimensions for Aln had not changed. Aln had higher BMC and ultimate load than OVX, EE2, and Rlx. EE2 and Rlx had similar biomechanical properties, which were similar to sham. Interestingly, OVX and Aln animals were heavier than other groups at all time points; therefore, ultimate load was normalized by body weight to show no significant differences in strength of the whole callus between groups at either 6 weeks or 16 weeks postfracture. However, Aln strongly suppressed remodeling of the callus, resulting in the highest content of woven bone, persistent visibility of the original fracture line, and lowest content of lamellar bone, compared with other groups. Therefore, the larger Aln callus appeared to be a remarkable, morphological adaptation to secure the fracture with inferior material. In conclusion, OVX-stimulated bone turnover resulted in the fastest progression of fracture repair that was most delayed with Aln treatment, consistent with marked suppression of bone resorption and formation activity. Estrogen and Rlx had similar effects that were generally similar to sham, indicating that mild suppression of bone turnover with these agents has insignificant effects on the progression of fracture repair.     

Comparative effects of 17β-estradiol,raloxifene and genistein on bone 3D microarchitecture and volumetric bone mineral density in the ovariectomized mice

Summary This study assessed the effect of estradiol, raloxifene and genistein on the preservation of bone 3D-microarchitecture and volumetric bone mineral density (vBMD) in the ovariectomized mouse model. Our results indicated that raloxifene was more effective in preserving bone ovariectomized-induced changes, the advantage being concentrated in both bone microarchitecture and vBMD. Introduction This study assessed the effect of different estrogen receptor (ER) agonists on the preservation of bone 3D-microarchitecture and volumetric bone mineral density (vBMD) in the ovariectomized (OVX) mouse model. Methods Twelve-week-old female C57BL/6 mice were randomly assigned to one of five groups: (1) SHAM-operated + vehicle; (2) OVX + vehicle; (3) OVX + 17β-estradiol (5 μg/kg); (4) OVX + raloxifene (1 mg/kg); (5) OVX + genistein (25 mg/kg), during 4-weeks. Bone microarchitecture and trabecular, cortical and total vBMD of distal femur were imaged by ex vivo microcomputed tomography (micro-CT). Results Ovariectomy produced a global deterioration involving both trabecular and cortical 3D-microarchitecture and vBMD. Raloxifene maintained both microarchitecture and vBMD, whereas estradiol prevented deterioration of some microstructural parameters, such as trabecular thickness (Tb.Th), trabecular bone pattern factor (Tb.Pf), and cortical periosteal perimeter (Ct.Pe.Pm), but did not completely block the loss in vBMD. Mice treated with genistein exhibited the less favourable profile in both vBMD and microstructural parameters preserving only cross-sectional bone area (B.Ar) and Ct.Pe.Pm in cortical bone. Conclusion Our data indicate that, at the selected doses, raloxifene was more effective in preserving bone OVX-induced changes than either estradiol or genistein, the advantage being concentrated in both bone microarchitecture and vBMD.     

Raloxifene and Vitamin K2 Combine to Improve the Femoral Neck Strength of Ovariectomized Rats

We evaluated the skeletal effects of two osteoporosis therapies in an ovariectomized rat model, raloxifene and vitamin K₂, as well as the vitamin K₂ plus raloxifene (K + Ral) combination. In two studies, 6-month-old rats were ovariectomized, except for sham-ovariectomy controls (Sham), and dosed orally with vehicle, 30 mg/kg vitamin K₂, 1 mg/kg raloxifene, or the combination of K + Ral for 6 weeks following surgery. Vitamin K₂ had no effect on serum estrogen, low-density lipoprotein cholesterol (LDL-C), or urinary deoxypyridinoline levels, but slightly increased osteocalcin levels compared to Ovx. Raloxifene lowered total cholesterol, LDL-C, osteocalcin, and urinary deoxypyridinoline levels to below Ovx levels, while having no effect on estrogen levels. Raloxifene, but not vitamin K₂, prevented ovariectomy-induced loss of bone in the distal femoral metaphysis and proximal tibial metaphysis, as did the K + Ral combination. Raloxifene, but not vitamin K₂, partially prevented, loss of vertebral bone mineral density (BMD), whereas K + Ral had BMD greater than that of Ovx. Vitamin K₂ increased bone formation rate to above Ovx, whereas raloxifene and K + Ral reduced bone formation rate to Sham levels. Vitamin K₂ had no effect on eroded surface compared to Ovx, while raloxifene and K + Ral reduced eroded surface to Sham levels. Groups were not different in the BMD of femoral midshaft; however vitamin K₂ was observed to increase periosteal mineralizing surface of the tibial shaft to above Ovx, while raloxifene reduced periosteal mineralizing surface toward Sham levels. Femoral neck strength was not different between groups, indicating no significant beneficial effect of either raloxifene or vitamin K₂ at this site. However, K + Ral had reproducibly greater femoral neck strength than Ovx or Sham. Raloxifene, but not vitamin K₂, partially prevented loss of lumbar vertebra strength; but K + Ral was not different from Sham or Ovx. Therefore, raloxifene and vitamin K₂ had complementary effects on bone resorption and formation activities, respectively, resulting in a reproducible, significant improvement of femoral neck strength. These rat data suggest interesting therapeutic possibilities that may require clinical verification. This work was supported by Lilly Research Laboratories.     

Raloxifene treatment is associated with increased serum estradiol and decreased bone remodeling in healthy middle-aged men with low sex hormone levels.

In healthy middle-aged men, raloxifene treatment was associated with increased serum estradiol and decreased biochemical markers of bone turnover in subjects with estradiol levels below a threshold of 101.8 pM. INTRODUCTION: We investigated the effects of the selective estrogen receptor modulator raloxifene on bone remodeling in healthy middle-aged men. MATERIALS AND METHODS: Forty-three healthy eugonadal men (mean age, 56 years; range, 49-70 years) were enrolled in a randomized placebo-controlled, double-blind, two-sequence crossover study. The subjects received either raloxifene 120 mg/day or placebo for 6 weeks, followed by a 2-month washout period, before crossing over. To predict changes of urinary total deoxypyridinoline/creatinine on raloxifene treatment, we used a logistic regression model to determine cut-off values of sex hormones for highest sensitivity and specificity. RESULTS: In the whole group, raloxifene treatment was associated with an increase in serum sex hormones, that is, total testosterone (+13%, p < 0.01), bioavailable testosterone (+11%, p = 0.02), total estradiol (+11%, p < 0.002), and bioavailable estradiol (+11%, p = 0.035), and with a decrease in serum osteocalcin (-13%, p < 0.05) and serum total alkaline phosphatase (-6%, p < 0.05). Other biochemical markers of bone turnover remained unchanged. Using a logistic regression model to predict changes in urinary deoxypyridoline, we calculated thresholds for total (101.8 pM) and bioavailable (4.79 pM) estradiol, as well as for total (19.4 nM) and bioavailable (0.35 nM) testosterone. Raloxifene treatment was associated with an increase in serum estradiol and decrease in biochemical markers of bone turnover in men with estradiol values below these estradiol thresholds, without any significant change in subjects with values above them. Similarly, raloxifene treatment was associated with an increase in serum testosterone and a decrease in biochemical markers of bone turnover in those with baseline testosterone values below the testosterone thresholds. The association between antiresorptive effects of raloxifene and low sex hormone levels was more pronounced for estradiol than for testosterone. CONCLUSIONS: The antiresorptive effect of raloxifene was only detectable in men with low baseline estradiol levels. Unlike in postmenopausal women, the increase of estradiol may contribute to the antiresorptive effect of raloxifene in men.     

雌激素对去势骨质疏松症大鼠骨密度和骨代谢影响的实验研究

目的研究雌激素对去势骨质疏松症模型大鼠骨密度(bone mineral density,BMD)和骨代谢的影响,并探讨其治疗骨质疏松症的机制。方法将48只雌性SD大鼠随机分配成对照组、模型组、雌激素组和雌激素+三苯氧胺组,每组12只。除对照组外,其他各组大鼠采用双侧卵巢摘除法制备骨质疏松症模型。雌激素组给予尼尔雌醇(1 mg/kg)灌胃,1次/周;雌激素+三苯氧胺组给予尼尔雌醇(1 mg/kg)和三苯氧胺(3 mg/kg)灌胃,1次/周;对照组和模型组分别使用等量生理盐水灌胃,均持续3个月。3个月后取材,检测大鼠左侧股骨BMD和股骨骨矿物盐含量、血清钙含量以及胫骨中骨骼钙含量;酶联免疫法检测大鼠血清碱性磷酸酶(alkaline phosphates,ALP)、血清抗酒石酸酸性磷酸酶-5b(tartrate resistant acid phosphatase-5b,TRAP-5b)的含量;免疫组化检测大鼠胫骨中骨保护素(osteoprotegerin,OPG)和核因子κB受体活化因子配体(receptor activator for nuclear factor-κB ligand,RANKL)蛋白的表达情况。结果治疗前,与对照组比较其他各组血清钙含量和血清TRAP-5b含量均显著升高(P0.05),骨钙含量、BMD和骨矿物盐含量显著降低(P0.05),血清ALP含量无显著性变化(P0.05);治疗后,与模型组比较雌激素组血清钙含量、血清TRAP-5b含量以及胫骨组织RANKL蛋白表达均显著降低(P0.05),骨钙含量、血清ALP含量、BMD、骨矿物盐含量以及胫骨组织OPG蛋白表达均显著升高(P0.05),而治疗后,与模型组比较雌激素+三苯氧胺组各项指标变化差异无统计学意义(P0.05)。结论雌激素通过显著性提高去卵巢骨质疏松模型大鼠骨骼钙、ALP、股骨骨密度、骨矿物盐以及OPG的含量,抑制骨钙流失、TRAP-5b及RANKL蛋白表达,达到改善骨质疏松的作用。     

Comparison of tamoxifen and testosterone propionate in male rats: differential prevention of orchidectomy effects on sex organs, bone mass, growth, and the growth hormone-IGF-I axis

Testis dysfunction can weaken bone and reduce muscle mass as well as impair sexual function. Testosterone (T) therapy has useful effects on sex organs, bone, and muscle in T-deficient males, but prostate concerns can preclude T use in some men. Although estrogens or other drugs can protect bone in men, gynecomastia makes estrogens unappealing, and other drugs may also be undesirable in some cases. Selective estrogen receptor modulators (SERMs) inhibit estrogen-evoked sex organ growth but mimic estrogen effects on bone and cholesterol and are advantageous for some women. SERMs may also be useful in men who must avoid androgens. As a preclinical test of this idea, tamoxifen (a SERM) and testosterone propionate (TP, a classic androgen) were compared for their efficacy in preventing varied effects of orchidectomy (ORX) in adult male rats. ORX led to ventral prostate and seminal vesicle atrophy and decreases in somatic growth, proximal tibia bone mineral density (BMD), and serum growth hormone (GH) and insulin-like growth factor I (IGF-I). ORX also increased anterior pituitary glandular kallikrein, serum cholesterol, and body temperature. Pituitary prolactin (PRL) content was unaltered. ORX effects on sex organs, somatic growth, IGF-I, cholesterol, body temperature, and pituitary kallikrein were prevented by TP at 1 mg/kg (3 doses per week), but BMD and GH were unresponsive. ORX effects on BMD and GH were prevented by TP at 10 mg/kg, but this dose evoked supraphysiologic increases in sex organs and PRL, failed to restore somatic growth, and further reduced IGF-I. Tamoxifen (1 mg/kg daily) prevented ORX effects on BMD, GH, and cholesterol without altering basal or TP-induced sex organ growth and further reduced IGF-I and somatic growth. Tamoxifen did not alter basal PRL but blocked increases caused by TP at 10 mg/kg. In summary, tamoxifen prevented ORX effects on bone and cholesterol in male rats without affecting sex organs or PRL and might be useful for men who must avoid androgens. Unexpectedly, a TP dose that replicated testis effects on sex organs and other targets had no effect on BMD or GH, and a larger TP dose that restored BMD and GH was worse at replicating normal male physiology. In addition, correlation/regression results suggested that the GH-IGF-I axis contributes to changes in BMD.     

Selective estrogen receptor modulators in chronic renal failure

BACKGROUND: In addition to renal osteodystrophy, postmenopausal women on dialysis could be at risk of osteoporosis. Hormone replacement therapy (HRT) could have beneficial effects as well as potentially serious risks, especially in uremic women, due to the pharmacokinetics of estradiol in renal failure. Therapeutic alternatives, such as the selective estrogen receptor modulators (SERMs), have shown the benefits of estrogen on bone and serum lipid levels, without its adverse effects on the breast and endometrium, in nonuremic women. METHODS: Recent data on the effect of the SERM raloxifene in bone and lipid metabolism in osteoporotic postmenopausal women on dialysis is reviewed. Since the estrogen receptor (ER) gene has been suggested as a candidate marker for osteoporosis, we investigated whether ER polymorphism could have predicted the BMD response to raloxifene. RESULTS: Hemodialyzed women on raloxifene demonstrated increased trabecular bone mineral density (BMD) and decreased bone resorption markers. Similarly, LDL-cholesterol values dropped significantly. ER gene polymorphism analysis of baseline BMD parameters did not differ between PP/xx or Pp/Xx groups. Nevertheless, patients on raloxifene with PP/xx genotypes, but not those with Pp/Xx, showed a higher trabecular BMD after one year on treatment, suggesting that homozygous women for P or x alleles of the ER have a better BMD response to raloxifene. CONCLUSION: Raloxifene and, most likely, other SERMs, could represent a good alternative to HRT in postmenopausal uremic women.     

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.     

Effects of SP500263, a Novel Selective Estrogen Receptor Modulator, on Bone, Uterus, and Serum Cholesterol in the Ovariectomized Rat

We describe here the activity of a novel selective estrogen receptor modulator, SP500263. When given to adult ovariectomized (OVX) rats for 28 days at doses of 0.3, 1, or 3 mg/kg/day, we found that SP500263 partially protected against OVX-induced loss of bone mineral content in the distal ends of femurs and in the whole bone. SP500263 also antagonized the OVX-induced increase in body weight. However, unlike 17-estradiol, SP500263 at efficacious doses did not prevent the OVX-induced loss in uterine wet weight. A small but significant effect on uterine wet weight was noted with raloxifene dosed at 1 mg/kg. As expected, SP500263 but not raloxifene acted as an estrogen antagonist on the uterus in adult rats when administered for 7 days at 30 mg/kg/day. Finally, SP500263 had no statistically significant effects on total serum cholesterol and serum triglycerides in OVX rats treated for 28 days. Raloxifene had no significant effects on body weight, bone mineral content, and serum cholesterol or triglycerides in the OVX-rat model. In summary, SP500263 is a new orally active SERM that acts in rats as an estrogen agonist on bone without causing uterine stimulatory effects. Present addresses: M. Kung Sutherland, Celltech R&D, Inc., Bothell, WA 98021, USA. L. M. Gayo-Fung, Structural Genomix Inc., San Diego, CA 92121, USA. E. OLeary, Chugai Pharma,USA, San Diego, CA 92121, USA, D. W. Anderson, Graceland University, Lamoni, IA 50140, USA.     

The Less Potent Estrogenic Effect of Tamoxifen on Bone in Ovariectomized Rats With Established Osteopenia

The longitudinal effects of tamoxifen (TAM) treatment on bone metabolism, spinal bone mineral density (BMD), and bone mineral content (BMC) were compared with those of estrogen in ovariectomized (OVX) rats with established osteopenia. The 6-month-old rats were divided into Sham (n = 8) and OVX (n = 24) groups. First, the OVX rats were allowed to lose bone for 6 weeks. Six weeks after ovariectomy they were divided into three groups: (1) OVX rats treated with solvent vehicle (OVX+Vehicle), (2) OVX rats injected with TAM subcutaneously six times a week at a dosage of 1.0 mg/kg body weight (OVX+TAM), (3) OVX rats injected with 17-β estradiol subcutaneously six times a week at a dosage of 0.1 mg/kg body weight (OVX+ET). The longitudinal effects of TAM and estrogen on bone were studied by dual energy X-ray absorptiometry (DXA) and biochemical markers including urinary pyridinoline (Pyr) and deoxypyridinoline (Dpyr). Ovariectomy resulted in a significant increase in urinary Pyr, Dpyr, and a significant decrease in spine BMD and BMC. TAM treatment completely inhibited the further bone loss in OVX rats with established osteopenia, however, estrogen increased spine BMD and BMC significantly compared with OVX+Vehicle, OVX+TAM, and baseline of treatment. Both TAM and estrogen treatment decreased urinary Pyr and Dpyr significantly in OVX rats. Our findings indicate that TAM acts as an estrogen agonist with respect to effects on spine BMD, BMC, and bone resorption in OVX rats with established osteopenia, but fails to restore spine BMD and BMC to the extent observed with estrogen in this study.     

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.     

Effect of a bisphosphonate and selective estrogen receptor modulator on bone remodeling in streptozotocin-induced diabetes and ovariectomized rat model

Background Context

Diabetes and menopause can cause severe osteoporosis. In general, menopause and diabetes can lead to an imbalance in bone turnover, which results in secondary osteoporosis. However, the efficacy of antiresorptive drugs against this form of osteoporosis has not been extensively evaluated.

Selective Estrogen Receptor Modulator Inhibits Osteocyte Apoptosis during Abrupt Estrogen Withdrawal: Implications for Bone Quality Maintenance

Estrogens exert positive effects on the quantity and quality of bone, including the maintenance of osteocytes through the inhibition of their apoptosis. Ideally, selective estrogen receptor modulators (SERMs) confer all of the positive bone-associated effects of estrogens without any adverse effects. In a similar way to estrogen, the raloxifene analog LY 117018 has been shown to prevent bone loss in ovariectomized (OVX) rats. In this study, we investigated whether the osteocyte-sparing effect of 17β-estradiol can be mimicked by the SERM LY 117018 in a rat model of OVX. Twenty-four juvenile female rats were divided into four treatment groups: sham-operated (SHAM), OVX, OVX + 17β-estradiol (OVX+E₂), and OVX + LY 117018 (OVX+SERM). At 7 or 14 days following the start of treatment, the radius and ulna were removed. The percentage of apoptotic osteocytes, determined using an in situ nick-translation method, was increased (2.5–fold at 7 days and sixfold at 14 days) in the OVX group compared with SHAM in both the radius and ulna. Treatment of OVX animals with either 17β-estradiol at a dose rate of 0.125 mg/kg/day or LY 117018 at a dose rate of 3 mg/kg/day prevented these increases in osteocyte apoptosis similarly. These observations demonstrate that LY 117018 exerts a powerful inhibitory effect upon osteocyte apoptosis directly after estrogen loss, in a similar way to the known effect of 17β-estradiol replacement. These results point to the potential benefits of SERMs on both the quantity and quality of bone in E₂-depleted rats.     

The effect of anti-resorptive therapies on bone graft healing in an ovariectomized rat spinal arthrodesis model

Bone grafting is commonly used to treat skeletal disorders associated with a large bone defect or unstable joint. Spinal arthrodesis surgery, which is the most common application of bone graft, is performed in the elderly and anti-resorptive therapy is sometimes started postoperatively in patients with bone fragility due to osteoporosis, despite insufficient knowledge about the effects of these drugs on bone graft healing. Therefore, we studied the effect of bisphosphonates (BP) and selective estrogen receptor modulators (SERM) on bone graft healing in an ovariectomized rat spinal arthrodesis model. Female Sprague-Dawley rats (n=100) were ovariectomized or sham-operated, and randomized into four groups: Sham (sham-operated+vehicle), Ovx (ovariectomy+vehicle), Ovx-Rlx (ovariectomy+raloxifene, 1 mg/kg/day), and Ovx-Aln (ovariectomy+alendronate, 0.01 mg/kg/day). Four weeks after ovariectomy, lumbar spinal arthrodesis surgery was performed using an autologous bone graft. Animals were killed 2, 4, and 8 weeks after surgery, and fusion assessment, three-dimensional micro-computed tomography, histomorphometry, mRNA expression analysis, and serum bone metabolic marker analysis were performed. The results indicated that neither BP nor SERM significantly altered the fusion rate, but the bone graft healing process was differentially affected. BP inhibited endochondral ossification and graft bone resorption, but induced the growth of a larger, denser fusion mass compared to Ovx by strongly suppressing osteoclastic activity. SERM mildly suppressed bone remodeling, but did not significantly inhibit the ossification process, leading to a fusion mass comparable with that of Sham animals. These findings suggested that spinal fusion surgery outcome is not likely to be altered by BP or SERM treatment started immediately after spinal arthrodesis surgery; however, to avoid adverse effects of BP on bone graft healing, BP treatment should be delayed during the immediate postoperative period.     

Inhibition of intimal hyperplasia using the selective estrogen receptor modulator raloxifene

HYPOTHESIS: The selective estrogen receptor modulator raloxifene hydrochloride inhibits intimal hyperplasia. DESIGN: Controlled laboratory experiment. SETTING: Experimental animal model. INTERVENTION AND MAIN OUTCOME MEASURES: Forty-three senile female sheep were randomized to sham operation, ovariectomy, or ovariectomy followed by treatment with 17beta-estradiol or raloxifene. Six months after initial operation, we performed necropsy with histological assessment of the aortic bifurcation and bone mineral densitometry and assayed serum lipids. RESULTS: After 6 months, serum triglyceride and total and high-density lipoprotein cholesterol levels were similar among groups and within the reference range. Ovarian ablation alone resulted in intimal hyperplasia, which was attenuated with estradiol and raloxifene therapy. Furthermore, estradiol and raloxifene therapy reversed ovariectomy-induced decreases in bone mineral density measured using spine morphometry. CONCLUSIONS: Raloxifene attenuates ovariectomy-induced aortic intimal hyperplasia independent of serum lipid levels. These data suggest that raloxifene, in addition to its beneficial influence on bone density, has direct, beneficial cardiovascular effects.     

A new selective estrogen receptor modulator HMR-3339 fully corrects bone alterations induced by ovariectomy in adult rats

The selective estrogen receptor modulator (SERM) raloxifene has been shown to reduce the risk of vertebral fracture, but without significant effect on nonvertebral fractures. However, there is a need for SERMs capable of improving mechanical competence and reducing the risk of fractures at multiple skeletal sites, with minimal side effects. We investigated the effects of a new steroidal SERM, HMR-3339, compared to raloxifene, on bone strength and its determinants (BMD, microarchitecture, dimensions) at various skeletal sites (lumbar spine, tibia, and femur) of adult ovariectomized rats in both prevention and intervention protocols. In a prevention study, HMR-3339 and raloxifene treatments fully prevented alterations of bone strength. In an intervention protocol, where treatment was started 8 weeks after ovariectomy, HMR-3339 fully restored mechanical properties by influencing both areal BMD and outer diameter. This effect was observed at skeletal sites formed of cancellous and cortical bone or of cortical bone only. In contrast, raloxifene positively influenced structures containing mainly cancellous bone. In HMR-3339-treated rats, IGF-I plasma levels were higher than in ovariectomized controls; this was not observed with raloxifene. In conclusion, these results indicate that HMR-3339 increased not only bone mineral mass, but also restored bone mechanical strength at multiple sites in adult osteoporotic rats. In contrast to raloxifene, HMR-3339 also influenced skeletal sites predominantly formed of cortical bone.     

Bone histomorphometric and biochemical marker results of a 2-year placebo-controlled trial of raloxifene in postmenopausal women.

Raloxifene is a selective estrogen receptor modulator that has been shown to increase bone density. The purpose of this study was to examine the effects of raloxifene on bone tissue by studying bone biopsy specimens before and after 2 years of raloxifene or placebo therapy. The women in this study were participants of the double-blind, placebo-controlled, multicenter study, the Multiple Outcomes of Raloxifene Evaluation (MORE) trial. Subjects from two U.S. sites and two European sites were included if they consented to a bone biopsy. Iliac crest bone biopsies were performed at baseline and after 2 years. Tetracycline labeling preceded each biopsy. A total of 65 paired biopsy specimens were evaluated with 25, 22, and 18 patients in the placebo, raloxifene HCl (60 mg) and raloxifene HCl (120 mg) treatment groups, respectively. They were analyzed using standard histomorphometry. None of the biopsy specimens showed evidence of toxic effects on bone or bone cells or met criteria for osteomalacia. Biopsy specimens in the placebo and raloxifene groups had the appearance of normal bone, with no evidence of marrow fibrosis or increases in the amount of woven bone or numbers of empty osteocyte lacunae. Compared with the baseline, the bone formation rate (BFR) decreased significantly in both raloxifene groups. The change in BFR in the group treated with 120 mg of raloxifene was -62.3%, which was significantly lower than the change in the placebo group of -21.0% (p = 0.03). No change in resorption parameters could be measured by histomorphometry, but there was a decrease in urinary type I collagen excretion. The results from this study suggest that raloxifene has actions on bone tissue that are similar to those observed with estrogen. The depressive effects on bone remodeling are less marked than the effects seen with alendronate.     

Effects of raloxifene on bone metabolism and serum lipids in postmenopausal women on chronic hemodialysis

BACKGROUND: Premature amenorrhea and hypoestrogenism and lack of hormone replacement therapy after menopause have been frequently reported in uremic women on dialysis. Therefore, in addition to renal osteodystrophy, postmenopausal women on dialysis could be at risk of osteoporosis. In addition, these patients are at higher risk for hyperlipidemia, arteriosclerosis, and subsequent coronary heart disease and stroke. Recent evidence has suggested that hormone replacement therapy (HRT) in postmenopausal women could have several beneficial effects as well as potentially serious risks. Great efforts have been made to identify therapeutic alternatives that would have the benefits of estrogen on brain and bone without its adverse effects on breast and endometrium. In the present study, we evaluated the effect of raloxifene, a selective estrogen receptor modulator (SERM), on bone metabolism and serum lipids in postmenopausal women on chronic hemodialysis. METHODS: We performed a prospective, blind, placebo-controlled, and randomized study. Fifty postmenopausal women on chronic hemodialysis with proven severe osteopenia or osteoporosis by bone densitometry were selected. After a written informed consent, patients were randomized into two groups: 25 women on placebo and 25 women on the study drug, raloxifene hydrochloride, at a dose of 60 mg/day. In all patients, we performed a baseline bone mineral density (BMD) analysis and simultaneously evaluated different biochemical parameters, serum lipids (total low-density lipoprotein [LDL] and high-density lipoprotein [HDL] cholesterol and triglycerides) and serum markers of bone resorption (pyridinoline crosslinks). BMD was reassessed after 1 year of therapy. Bone resorption markers were determined every 3 months for 1 year. RESULTS: After 1 year on raloxifene therapy, lumbar spine BMD (trabecular bone) significantly improved, whereas femoral neck BMD (cortical bone) did not change significantly. No changes in BMD were observed at trabecular or cortical sites in the placebo group. Serum pyridinoline levels showed a significant decrease after 6 months on raloxifene that persisted thereafter. Low-density lipoprotein (LDL)-cholesterol decreased significantly in the raloxifene group with no changes in serum triglycerides, total cholesterol, or HDL cholesterol. No significant side effects were observed in the raloxifene group. CONCLUSION: The study demonstrates that after one year on raloxifene, postmenopausal women on hemodialysis have a significant increase in trabecular BMD, decrease in bone resorption markers and LDL-cholesterol values, suggesting that SERMs could constitute a therapeutic alternative to improve bone metabolism and control of hyperlipidemia in these patients. The possible long-term effects of raloxifene remain to be determined.     

The effects of clodronate on increased bone turnover and bone loss due to ovariectomy in rats

The present study was carried out to investigate the ability of clodronate to inhibit ovariectomy-induced bone loss and increased bone turnover in rats. Estradiol was administered as a reference compound. Seventy Sprague-Dawley rats were ovariectomized (OVX) or sham-operated (Sham) at the age of 90 days and divided into seven groups. Two Sham and two OVX groups received subcutaneously either the vehicle of clodronate or the vehicle of estradiol. Other OVX groups were given s.c. either disodium clodronate at two dose levels (5 mg/kg or 12.5 mg/kg twice a week) or 17β-estradiol (10 μg/kg five times a week) for 8 weeks. Femur length, volume, dry weight, and ash weight were determined, and proximal ends of tibiae were used for bone histomorphometry. Markers of bone metabolism were measured from urine and serum. A significant loss of 54% of trabecular bone area of proximal tibial metaphysis was found at 8 weeks after ovariectomy. Clodronate and estradiol inhibited (p < 0.001) this osteopenia. Both drugs prevented the decrease in ash weight/volume of the femur. The inhibitory effect of clodronate and estradiol on bone resorption in OVX rats could be detected also in decreased urinary excretion of hydroxyproline and lysylpyridinoline (p < 0.001). Clodronate and estradiol decreased (p < 0.001) the ovariectomy-induced enhanced tibial endocortical mineral apposition rate (Ec.MAR) on the lateral cortex to the level of the Sham group. In contrast, periosteal MAR analyzed on the medial side of tibial cortical bone did not change significantly in the OVX/Veh group. Estradiol decreased periosteal MAR to below the level in the Sham group (p < 0.01). These results suggest that ovariectomy of growing rats resulted in tibial and femoral osteopenia two months later. Clodronate as well as estradiol can suppress bone resorption and turnover in ovariectomized rats, inhibiting the development of osteopenia. Both clodronate doses (5 and 12.5 mg/kg) had beneficial effects in ovariectomized animals.