Short- to mid-term effects of ovariectomy on bone turnover, bone mass and bone strength in rats

The Effect of Menopause on Vaginal Tissue Mechanics: A Brief Review

Often called "the change of life," menopause affects every part of a woman's body. As the sex hormones decrease, the reproductive organs experience the most remarkable changes, with the vagina becoming thinner, drier, and less elastic. Despite the important implications of these changes in genitourinary conditions, there are only a few experimental studies that focus on quantifying the effect of menopause on the mechanical properties of the vagina. These studies are mostly conducted using uniaxial tests on strips of vaginal tissues isolated from rats, rabbits, and sheep and, in only a few cases, from humans. The purpose of this article is to present a systematic review of experimental protocols, methods, and results that are currently published on how menopause alters the mechanical behavior of the vagina. This review will enable new investigators in the biomechanics field to identify important gaps and frame research questions that inform the design of new treatment options for menopausal symptoms.

The nanoformula of zoledronic acid and calcium carbonate targets osteoclasts and reverses osteoporosis

Osteoporosis is known as an imbalance in bone catabolism and anabolism. Overactive bone resorption causes bone mass loss and increased incidence of fragility fractures. Antiresorptive drugs are widely used for osteoporosis treatment, and their inhibitory effects on osteoclasts (OCs) have been well established. However, due to the lack of selectivity, their off-target and side effects often bring suffering to patients. Herein, an OCs' microenvironment-responsive nanoplatform HA-MC/CaCO₃/ZOL@PBAE-SA (HMCZP) is developed, consisting of succinic anhydride (SA)-modified poly(β-amino ester) (PBAE) micelle, calcium carbonate shell, minocycline-modified hyaluronic acid (HA-MC) and zoledronic acid (ZOL). Results indicate that HMCZP, as compared with the first-line therapy, could more effectively inhibit the activity of mature OCs and significantly reverse the systemic bone mass loss in ovariectomized mice. In addition, the OCs-targeted capacity of HMCZP makes it therapeutically efficient at sites of severe bone mass loss and allows it to reduce the adverse effects of ZOL, such as acute phase reaction. High-throughput RNA sequencing (RNA-seq) reveals that HMCZP could down-regulate a critical osteoporotic target, tartrate-resistant acid phosphatase (TRAP), as well as other potential therapeutical targets for osteoporosis. These results suggest that an intelligent nanoplatform targeting OCs is a promising strategy for osteoporosis therapy.

The Gradual Release of Alendronate for the Treatment of Critical Bone Defects in Osteoporotic and Control Rats

Purpose

Osteoporosis is a severe health problem with social and economic impacts on society. The standard treatment consists of the systemic administration of drugs such as bisphosphonates, with alendronate (ALN) being one of the most common. Nevertheless, complications of systemic administration occur with this drug. Therefore, it is necessary to develop new strategies, such as local administration.

Methods

In this study, emulsion/dispersion scaffolds based on W/O emulsion of PCL and PF68 with ALN, containing hydroxyapatite (HA) nanoparticles as the dispersion phase were prepared using electrospinning. Scaffolds with different release kinetics were tested in vitro on the co-cultures of osteoblasts and osteoclast-like cells, isolated from adult osteoporotic and control rats. Cell viability, proliferation, ALP, TRAP and CA II activity were examined. A scaffold with a gradual release of ALN was tested in vivo in the bone defects of osteoporotic and control rats.

Results

The release kinetics were dependent on the scaffold composition and the used system of the poloxamers. The ALN was released from the scaffolds for more than 22 days. The behavior of cells cultured in vitro on scaffolds with different release kinetics was comparable. The difference was evident between cell co-cultures isolated from osteoporotic and control animals. The PCL/HA scaffold show slow degradation in vivo and residual scaffold limited new bone formation inside the defects. Nevertheless, the released ALN supported bone formation in the areas surrounding the residual scaffold. Interestingly, a positive effect of systemic administration of ALN was not proved.

Conclusion

The prepared scaffolds enabled tunable control release of ALN. The effect of ALN was proved in vitro and in in vivo study supported peri-implant bone formation.

Effects of Ovariectomy and Exercise Training on Mineral Status in a High-Fat Diet-Induced Obesity Rat Model

Osteoporosis is a growing public health issue for an aging society. Previous studies have found both beneficial and detrimental effects of obesity on bone health. The purpose of this study was to investigate the impact of estrogen deficiency and physical activity on bone and blood concentrations of macrominerals (Ca, P, and Mg) and microminerals (Zn, Se, Cu, and Fe) in a high-fat diet-induced obesity rat model. Forty-eight female Wistar rats were divided into six groups: sham-operated and ovariectomized rats that received a standard diet (SD), high-fat diet (HFD), or HFD accompanied by physical exercise. The effect of ovariectomy on bone minerals varied with diet. Ovariectomy significantly decreased femoral Ca and Mg in sedentary rats receiving a SD; femoral Se, Cu, Zn, and Fe in sedentary rats on HFD; and plasma Fe in both sedentary rats on SD and exercising rats on HFD. The interaction of ovariectomy and diet had the strongest impact on Mg and Se concentrations in femur. In ovariectomized rats, HFD showed to have a protective effect on bone mineralization (femoral Ca and Mg), and a negative one on antioxidant microminerals (femoral Se, Cu, and Zn). Physical activity reduced the decline of Se, Cu, Zn, and Fe in the femur of ovariectomized rats on HFD. In the current state of knowledge, it is difficult to suggest if decreased femoral levels of antioxidant microminerals may contribute to the pathophysiology of osteoporosis in obese individuals or just reflect the mineral status in the body.

Osteocyte Wnt/β-catenin pathway activation upon mechanical loading is altered in ovariectomized mice

Estrogen levels decline in both sexes with age, but more dramatically in females. Activation of the Wnt/β-catenin signaling pathway is central to the regulation of bone mass accrual and maintenance and in response to mechanical loading. Using the ovariectomized mouse model we examined the effect of estrogen loss on the osteocyte's ability to activate the Wnt/β-catenin pathway following mechanical loading. Female TOPGAL mice underwent ovariectomy (OVX) (n = 10) or sham surgery (n = 10) at 16 weeks of age. Four weeks post-surgery, a single loading session (global strain of 2200 με for 100 cycles at 2 Hz) was performed on the right forearm with the left as a non-loaded control. Mice (n = 5) were sacrificed at 1 or 24 hr post-load. Ulnae were stained for β-catenin activation, femurs were used for μCT and 3-pt bending/biomechanical testing, and tibiae were used for histology analysis and to determine osteocyte lacunar size using SEM and high resolution micro-XCT. A 2.2-fold increase in β-catenin signaling activation was observed 24 hr post-load in the Sham group but did not occur in the OVX group. The OVX group versus control had significant losses (p < 0.05) in trabecular BMD (−8%), BV/TV (−35%) and thickness (−23%), along with cortical thickness (−6%) and periosteal perimeter (−4%). The OVX group had significantly higher trabecular bone osteoclast numbers (63%), OCS/BS (77%) and N.OC/BPm (94%) and a significant decrease in osteoblast number (53%), OBS/BS (37%) and N.OB/BPm (40%) compared to the sham group (p < 0.05). Cortical bone lacunar number/lacunar volume and bone biomechanical properties did not change between groups. Given that the ulna is a cortical bone loading model and the lack of changes in osteocyte lacunar number/volume in cortical bone, which would alter strains experienced by osteocytes, these data suggest the absence of estrogen resulted in intrinsic changes in the ability of the osteocyte to respond to mechanical load, rather than changes in the biomechanical and architectural properties of bone.

•

In vivo mechanical loading activates β-catenin signaling in osteocytes.

•

Ovariectomy induced estrogen loss attenuates in vivo loading induced β-catenin signaling in osteocytes.

•

Changes in bone material and architectural properties do not appear to explain attenuated pathway activation.

•

Our data suggests estrogen loss alters the intrinsic ability of the osteocyte to respond to mechanical load.

Changes in Bone Metabolism and Antioxidant Defense Systems in Menopause-Induced Rats Fed Bran Extract from Dark Purple Rice (Oryza sativa L. Cv. Superjami)

Menopause is a matter of concern for women’s health due to a deficiency of female hormones; additionally, reactive oxygen species and aging can cause osteoporosis. Food becomes increasingly interesting as a menopausal woman’s alternative to hormone therapy. The effects of ethanol extracts from dark purple Superjami rice bran on bone metabolism and antioxidant defense systems in menopause-induced animal models were evaluated. Female rats underwent sham surgery or were ovariectomized to induce a menopause-like state. Rats were divided into a sham control group (SHAM), an ovariectomized control group (OVX), and an ovariectomized grou supplemented with Superjami rice bran extract group (OVX-S) and fed for 8 weeks. The OVX groups exhibited significantly more weight gain, amounts of bone turnover biochemical markers (alkaline phosphatase, osteocalcin, and C-terminal telopeptide), bone loss, lipid-peroxidation and oxidative stress than the SHAM group. However, Superjami bran extract added to the diet resulted in a significant reduction in body weight and lipid peroxidation, as well as enhanced bone metabolism and antioxidant enzyme activities, in ovariectomized rats. These results propound that extracts from Superjami rice bran have therapeutic potentiality against bone loss and oxidative stress in menopause-induced states and will be useful in preventing postmenopausal osteoporosis and oxidative damage.

Metabolomics and physiological analysis of the effect of calcium supplements on reducing bone loss in ovariectomized rats by increasing estradiol levels

BACKGROUND

Data from the 2010-2012 Chinese National Nutrition and Health Survey showed that the vast majority of postmenopausal women in China had dual deficiencies in calcium and estrogen.

OBJECTIVE

This study aimed to clarify whether calcium supplementation alleviated bone loss caused by calcium restriction combined with estrogen deficiency in rats.

METHODS

Forty-eight female rats aged 9 weeks were assigned to 4 groups and fed a low-calcium diet: sham-operated (SHAM-LC), ovariectomized (OVX-LC), and ovariectomized rats treated with 750 mg/kg (OVX-LC-M) or 2800 mg/kg CaCO3 (OVX-LC-H). CaCO3 or distilled water was administered orally for 13 weeks. Bone mineral density (BMD) and histomorphometry of the femur, serum biochemical parameters, and serum metabolites were analyzed.

RESULTS

The OVX-LC rats showed a significant increase in body weight and serum levels of lipid markers, a significant decrease in serum estradiol, calcium, phosphorus, and 25(OH)D levels, and deterioration of the femur. At 750 mg/kg and 2800 mg/kg, CaCO3 reduced the deterioration of trabecular bone and increased the trabecular area percentage (Tb.Ar %) and BMD of the femur. Serum estradiol levels increased in a dose-dependent manner after CaCO3 supplementation (p < 0.01). The administration of 2800 mg/kg CaCO3 decreased serum triglyceride and high-density lipoprotein levels (p < 0.05) and decreased the levels of the bone turnover markers osteocalcin, N-telopeptide of type I collagen and β-crosslaps. The results of the metabolomics analysis showed that the glycerophospholipid metabolism pathway was closely related to calcium supplementation, and more DG (44:6 n3), LysoPC (22:2) and PE (P-34:3) and less Cer (d43:0) and PE-NMe2 (46:3) were produced.

CONCLUSIONS

The results clearly indicated that calcium supplementation was beneficial for decreasing bone loss in OVX-LC rats. The present study is the first to show that calcium supplementation increased the estradiol content in OVX-LC rats, and the effect of calcium on bone loss may be partially attributed to the increase in the estrogen level that subsequently induced the changes in metabolite levels, eventually increasing the bone mineral density to a relatively higher level to reduce bone deterioration.

Ovariectomized rat model of osteoporosis: a practical guide

Osteoporosis affects about 200 million people worldwide and is a silent disease until a fracture occurs. Management of osteoporosis is still a challenge that warrants further studies for establishing new prevention strategies and more effective treatment modalities. For this purpose, animal models of osteoporosis are appropriate tools, of which the ovariectomized rat model is the most commonly used. The aim of this study is to provide a 4-step guideline for inducing a rat model of osteoporosis by ovariectomy (OVX): (1) selection of the rat strain, (2) choosing the appropriate age of rats at the time of OVX, (3) selection of an appropriate surgical method and verification of OVX, and (4) evaluation of OVX-induced osteoporosis. This review of literature shows that (i) Sprague-Dawley and Wistar rats are the most common strains used, both responding similarly to OVX; (ii) six months of age appears to be the best time for inducing OVX; (iii) dorsolateral skin incision is an appropriate choice for initiating OVX; and (iv) the success of OVX can be verified 1-3 weeks after surgery, following cessation of the regular estrus cycles, decreased estradiol, progesterone, and uterine weight as well as increased LH and FSH levels. Current data shows that the responses of trabecular bones of proximal tibia, lumbar vertebrae and femur to OVX are similar to those in humans; however, for short-term studies, proximal tibia is recommended. Osteoporosis in rats is verified by lower bone mineral density and lower trabecular number and thickness as well as higher trabecular separation, changes that are observed at 14, 30, and 60 days post-OVX in proximal tibia, lumbar vertebrae and femur, respectively.

A multi-factorial analysis of bone morphology and fracture strength of rat femur in response to ovariectomy

BACKGROUND

Postmenopausal osteoporosis develops due to a deficiency of estrogen that causes a decrease in bone mass and changes in the macro- and micro-architectural structure of the bone, leading to the loss of mechanical strength and an increased risk of fracture. Although the assessment of bone mineral density (BMD) has been widely used as a gold standard for diagnostic screening of bone fracture risks, it accounts for only a part of the variation in bone fragility; thus, it is necessary to consider other determinants of bone strength. Therefore, we aimed to comprehensively evaluate the architectural changes of the bone that influence bone fracture strength, together with the different sensitivities of cortical and trabecular bone in response to ovariectomy (OVX).

METHODS

Bone morphology parameters were separately analyzed both in cortical and in trabecular bones, at distal-metaphysis, and mid-diaphysis of OVX rat femurs. Three-point bending test was performed at mid-diaphysis of the femurs. Correlation of OVX-induced changes of morphological parameters with breaking force was analyzed using Pearson's correlation coefficient.

RESULTS

OVX resulted in a decline in the bone volume of distal-metaphysis trabecular bone, but an increase in distal-metaphysis and mid-diaphysis cortical bone volume. Tissue mineral density (TMD) remained unchanged in both the trabecular and cortical bone of the distal metaphysis but decreased in cortical bone of the mid-diaphysis. The OVX significantly increased the breaking force at mid-diaphysis of the femurs.

CONCLUSIONS

OVX decreased the trabecular bone volume of the distal-metaphysis and increased the cortical bone volume of the distal-metaphysis and mid-diaphysis. Despite the reduction in TMD and increased cortical porosity, bone fracture strength increased in the mid-diaphysis after OVX. These results indicate that analyzing a single factor, i.e., BMD, is not sufficient to predict the absolute fracture risk of the bone, as OVX-induced bone response vary, depending on the bone type and location. Our results strongly support the necessity of analyzing bone micro-architecture and site specificity to clarify the true etiology of osteoporosis in a clinical setting.

Taurine May Modulate Bone in Cholesterol Fed Estrogen Deficiency-Induced Rats

Taurine is thought to affect bone in rats favorably. However, studies on the actions of this estrogen deficiency and high cholesterol diet factors on the bone metabolism are limited. In this study, the protective effect of taurine on bone was determined. Thirty-two 42 days old female SD rats were placed in individual stainless cages. Given to rats was fed to chow (Samyang Corporation, South Korea) and deionized water for a 4 days adaptation period. After the period of adaptation, Half of the rats were induced estrogen deficiency model by ovariectomy (OVX), and the left rats with sham-operated were used control (SHAM). For six weeks, the OVX and SHAM rats had separately a 2% taurine supplemented diet with ad libitum in both the water and the food. DEXA for small animals (PIXImus, GE Lunar co, Wisconsin) was used to determine spinal and femoral bone. The concentrations of serum calcium and phosphorus were also measured. The monitoring of bone formation was done by determining the serum ALP and osteocalcin. Urinary DPD the values were determined as index of bone resorption. Statistical measure was done with SAS (version 9.3). A lower overall intake of the daily food was observed in non-ovariectomized rats than in the OVX rats. At sacrifice, a much greater body weight was observed in ovariectomized group compare to non-operated group. That difference was absent in both fed taurine SHAM and OVX rats. Serum calcium and phosphorus were not statistically different by taurine supplementation. Urinary excretion of calcium was not effected by taurine supplementation. Serum ALP and was significantly decreased by taurine in OVX rats (p < 0.05). For the spine BMD and BMC, there was no difference among SHAM and OVX rats by taurine. Spine BMC per body weight of taurine groups were higher than control groups (p < 0.1). No significant difference was observed after taurine supplementation in femur BMD and BMC. The analysis of the results suggest that taurine supplementation modulates the bone mineral contents in postmenopausal model rats fed with high cholesterol diet.

Indução do estro em cutias (Dasyprocta leporina) utilizando-se protocolos à base de prostaglandina isolada ou em associação com análogo de GnRH

RESUMO Comparou-se a eficiência de protocolos para indução de estro em cutias. Em cinco fêmeas, foram administradas duas doses de cloprostenol (5µg) com intervalo de nove dias, via intraperitoneal; em outras cinco, administraram-se 30µg de análogo do hormônio liberador de gonadotrofinas (GnRH), via intravulvar, seguidos de 5µg de cloprostenol, via intraperitoneal, após sete dias e, após mais dois dias, nova dose do análogo de GnRH. A cada três dias, a ciclicidade reprodutiva dos animais foi monitorada, por meio de coleta de sangue, para dosagem hormonal, ultrassonografia ovariana e citologia vaginal. Duas das fêmeas que receberam apenas prostaglandina, as quais estavam em fase luteal no início do tratamento, manifestaram o estro aos três e seis dias após a segunda administração da droga. Já nas fêmeas que receberam a prostaglandina associada ao análogo do GnRH, duas que originalmente estavam em fase luteal apresentaram estro aos quatro dias após o tratamento, e uma outra apenas após 10 dias. Não foram evidenciadas diferenças estatísticas quanto à eficiência dos tratamentos (P>0,05). Conclui-se que, de acordo com os protocolos utilizados, o uso da prostaglandina isolada ou em associação com análogo do GnRH para a indução do estro em cutias D. leporina apresenta eficiência limitada às fêmeas que estejam em fase luteal por ocasião do início do tratamento.

Soy protein improves tibial whole-bone and tissue-level biomechanical properties in ovariectomized and ovary-intact, low-fit female rats

BACKGROUND

Osteoporosis and related fractures, decreased physical activity, and metabolic dysfunction are serious health concerns for postmenopausal women. Soy protein might counter the negative effects of menopause on bone and metabolic health due to the additive or synergistic effects of its bioactive components.

OBJECTIVE

To evaluate the effects of ovariectomy (OVX) and a soy-protein diet (SOY) on bone outcomes in female, low-capacity running (LCR) rats selectively bred for low aerobic fitness as a model of menopause.

METHODS

At 27 weeks of age, LCR rats (N = 40) underwent OVX or sham (SHAM) surgery and were randomized to one of two isocaloric and isonitrogenous plant-protein-based dietary treatments: 1) soy-protein (SOY; soybean meal); or, 2) control (CON, corn-gluten meal), resulting in four treatment groups. During the 30-week dietary intervention, animals were provided ad libitum access to food and water; body weight and food intake were measured weekly. At completion of the 30-week intervention, body composition was measured using EchoMRI; animals were fasted overnight, euthanized, and blood and hindlimbs collected. Plasma markers of bone formation (osteocalcin, OC; N-terminal propeptide of type I procollagen, P1NP) and resorption (tartrate-resistant acid phosphatase, TRAP5b; C-terminal telopeptide of type I collagen, CTx) were measured using ELISA. Tibial trabecular microarchitecture and cortical geometry were evaluated using μCT; and torsional loading to failure was used to assess cortical biomechanical properties. Advanced glycation end-product (AGE) content of the femur was measured using a fluorimetric assay, and was expressed relative to collagen content measured by a colorimetric OH-proline assay. Two-factor ANOVA or ANOVCA was used to test for significant main and interactive effects of ovarian status (OV STAT: OVX vs. SHAM) and DIET (SOY vs. CON); final body weight was included as a covariate for body-weight-dependent cortical geometry and biomechanical properties.

RESULTS

OVX had significantly greater CTx than SHAM; SOY did not affect bone turnover markers. OVX adversely affected trabecular microarchitecture as evidenced by reduced BV/TV, trabecular thickness (Tb.Th), trabecular number (Tb.N), and connectivity density (Conn.D), and by increased trabecular separation (Tb.Sp) and structural model index (SMI). SOY increased BV/TV only in ovary-intact animals. There was no effect of OVX or SOY on tibial cortical geometry. In SHAM and OVX rats, SOY significantly improved whole-bone strength and stiffness; SOY also increased tissue-level stiffness and tended to increase tissue-level strength (p = 0.067). There was no effect of OVX or SOY on AGE content.

CONCLUSION

Soy protein improved cortical bone biomechanical properties in female low-fit rats, regardless of ovarian hormone status.

Effect of the lipoxygenase-inhibitors baicalein and zileuton on the vertebra in ovariectomized rats

Osteoporosis is one of the most common diseases worldwide. In osteoporosis, vertebral fractures represent a major burden. Lipoxygenase (LOX) inhibitors such as baicalein and zileuton may represent a promising therapeutic option owing to their antioxidative effects and suppression of various inflammatory processes in muscle and bone. The effect of these LOX inhibitors on the spine was studied in osteopenic rats. Female Sprague-Dawley rats were divided two times into five groups: four groups each were ovariectomized (OVX) and one control group was non-ovariectomized (NON-OVX). Eight weeks after ovariectomy, three concentrations of baicalein (1mg/kg body weight [BW], 10mg/kgBW, and 100mg/kgBW) were administered subcutaneously daily in three OVX groups for 4weeks. Similarly, zileuton was administered in three concentrations via food for 5weeks. In vivo computed tomography (pQCT) of the spine was performed before the treatments and at the end of the experiment. Lumbar vertebrae were subjected to a compression test, micro-CT, and ashing analyses. After baicalein treatment, cortical bone mineral density (BMD) was improved; trabecular connectivity and trabecular BMD were diminished at high dose. After zileuton treatment, the total BMD, anorganic weight, trabecular nodes, and trabecular area were improved. The in vivo stress-strain index was increased and alkaline phosphatase activity in serum was enhanced after both treatments. A dose-dependent effect was not clearly observed after both treatments. The treatments using baicalein for 4 and zileuton for 5weeks were not sufficient to change the biomechanical properties and bone volume fraction (BV/TV). Overall, baicalein improved the cortical bone parameters whereas zileuton had a favorable effect on the trabecular structure. Moreover, both treatments increased the bone formation rate. Longer trials, a combination of both LOX inhibitors, and their effect at the cellular and molecular levels should be investigated in further studies.

The effect of PDE5 inhibitors on bone and oxidative damage in ovariectomy-induced osteoporosis

Osteoporosis is a major public health problem associated with many factors, and it affects more than 50% of women over 50 years old. In the current study, our purpose was to investigate the effects of phosphodiestarase-5 inhibitors on osteoporosis via the nitric oxide/3',5'-cyclic guanosine monophosphate/protein kinase G signalling pathway. A total of 50 female albino Wistar rats were separated into five groups. The first group was appointed as the healthy control group with no ovariectomy. All animals in the other groups underwent a bilateral ovariectomy. Six months after the ovariectomy, vardenafil, udenafil and tadalafil were given to the third, fourth and fifth groups, respectively, but were not administered to the positive control group (10 mg/kg per day for two months). The bone mineral density values were determined using a densitometry apparatus for all groups pre- and post-ovariectomy as well as after treatment. The levels of nitric oxide, endothelial nitric oxidesynthase, asymmetric dimethylarginine, 3',5'-cyclic guanosine monophosphate, protein kinase G, phosphodiestarase-5, pyridinoline, deoxypyridinoline, carboxyterminal telopeptide fragments and plasma carboxy terminal propeptide of type I collagen were determined using an enzyme linked immunosorbent assay. The levels of malondialdehyde, 8-hydroxy-2-deoxy guanosine, deoxyguanosine and coenzyme Q10 were determined by a high-performance liquid chromatography assay. Additionally, the right femoral trabecular bone density and the epiphyseal plate were measured in all groups. Angiogenesis was histologically observed in the bone tissue. In addition, we determined that the inhibitors may have caused a positive impact on the increased bone mass density and reduction of bone resorption markers. We also observed the positive effects of these inhibitors on oxidative stress. In conclusion, these phosphodiestarase-5 inhibitors increase angiogenesis in bone tissue and improve the re-formation rate of bone in rats with osteoporosis. Chemical compounds studied in this article Udenafil (PubChem CID: 6918523); Tadalafil (PubChem CID: 110635); Vardanafil (PubCham CID: 110634). Impact statement The results in our study appear to establish the osteoporosis model and provide evidence of the positive effects of three separate PDE5 inhibitors (vardenafil, udenafil, and tadalafil). The positive effects of these PDE5 inhibitors are investigated and demonstrated by the bone mass density and bone resorption markers. These effects are associated with significant demonstrated antioxidant activities. Osteoporosis is a significant major public health problem especially in more aged populations. Advances in identifying and understanding new potential therapeutic modalities for this disease are significant. This study provides such an advance.

Lifelong intake of flaxseed or menhaden oil to provide varying n-6 to n-3 PUFA ratios modulate bone microarchitecture during growth, but not after OVX in Sprague-Dawley rats

SCOPE

Skeletal health is a lifelong process impacted by environmental factors, including nutrient intake. The n-3 source and PUFA ratio affect bone health in growing rats, or following ovariectomy (OVX), but no study has investigated the longitudinal effect of PUFA-supplementation throughout these periods of bone development.

METHODS AND RESULTS

One-month-old, Sprague-Dawley rats (n = 98) were randomized to receive one of four diets from 1 through 6 months of age. Diets were modified from AIN-93G to contain a varying amount and source of n-3 (flaxseed versus menhaden oil) to provide an n-6 to n-3 ratio of 10:1 or 5:1. At 3 (prior to SHAM or OVX) and 6 months of age, bone microarchitecture of the tibia was quantified using in vivo micro-computed tomography (SkyScan 1176, Bruker microCT). Providing 5:1 (flaxseed) resulted in lower trabecular thickness and medullary area and greater cortical area fraction during growth compared to diets with a 10:1 PUFA ratio, but many of these differences were not apparent following OVX.

CONCLUSION

PUFA-supplementation at levels attainable in human diet modulates some bone structure outcomes during periods of growth, but is not an adequate strategy for the prevention of OVX-induced bone loss in rats.

Anti-Osteoporotic Activity of Harpagoside by Upregulation of the BMP2 and Wnt Signaling Pathways in Osteoblasts and Suppression of Differentiation in Osteoclasts

Harpagoside (1) is an iridoid glycoside isolated from the radix of Harpagophytum procumbens var. sublobatum, commonly called Devil's claw. The anti-osteoporotic effect of 1 was investigated in both in vitro cell cultures and in vivo using an ovariectomized (OVX) mouse model. Compound 1 induced bone formation by stimulating osteoblast proliferation, alkaline phosphatase activity, and mineralization in osteoblastic MC3T3-E1 cells. Treatment with 1 increased the mRNA and protein expression of bone formation biomarkers through regulation of the BMP2 and Wnt signaling pathway in MC3T3-E1 cells. Compound 1 also suppressed the RANKL-induced osteoclastogenesis of cultured mouse bone marrow cells. Oral administration of 1 restored the OVX-induced destruction of trabecular bone. The bone mineral density of the femur was also increased significantly by 1. The elevated serum levels of osteocalcin, C-terminal telopeptide, and tartrate-resistant acid phosphatase in the OVX mice were decreased by treatment with 1. These findings suggest that compound 1 may protect against bone loss induced by OVX in mice by regulating stimulation of osteoblast differentiation and inhibition of osteoclast resorption. Therefore, harpagoside (1) is a potential candidate for management of postmenopausal osteoporosis.

Effect of Concurrent Use of Whole-Body Vibration and Parathyroid Hormone on Bone Structure and Material Properties of Ovariectomized Mice

This study was designed to determine the effectiveness of whole-body vibration (WBV) and intermittent parathyroid hormone (iPTH) in combination against estrogen deficiency-induced osteoporosis. Female C57BL/6J mice were bilaterally ovariectomized (OVX, n = 40) or sham-operated (sham-OVX, n = 8) at 9 weeks of age. Two weeks later, the OVX mice were randomly divided into four groups (n = 10 each): the control group (c-OVX) and groups treated with iPTH (p-OVX), WBV (w-OVX) and both (pw-OVX). The p-OVX and pw-OVX groups were given human PTH (1-34) at a dose of 30 µg/kg/day. The w-OVX and pw-OVX groups were exposed to WBV at an acceleration of 0.3 g and 45 Hz for 20 min/day. All mice were euthanized after the 18-day treatment, and the left tibiae were harvested. The proximal metaphyseal region was µCT-scanned, and its cortical bone cross-section was analyzed by Fourier transform infrared microspectroscopy and nanoindentation testing. A single application of iPTH or WBV to OVX mice had no effect on bone structure or material properties of cortical bone, which were compromised in comparison to those in sham-OVX mice. The combination of iPTH and WBV improved trabecular bone volume, thickness, and connectivity in OVX mice. Although the combined treatment failed to improve cortical bone structure, its mineral maturity and hardness were restored to the levels observed in sham-OVX mice. There was no evidence of interaction between the two treatments, and the combined effects seemed to be additive. These results suggest combining WBV with iPTH has great potential for treating postmenopausal osteoporosis.

Anti-osteoporotic activity of harpagide by regulation of bone formation in osteoblast cell culture and ovariectomy-induced bone loss mouse models

ETHNOPHARMACOLOGICAL RELEVANCE

Harpagide, an iridoid glucoside, is a constituent of the root of Harpagophytum procumbens var. sublobatum (Engl.) Stapf, Devil's claw which has been used in patients with osteoarthritis (OA). In the present study, we investigated the anti-osteoporotic potential of harpagide and its underlying mechanism of action in in vitro cell culture and in vivo bone loss animal models.

MATERIAL AND METHODS

Harpagide was obtained from the alkalic hydrolysis of harpagoside, a major constituent of H. procumbens var. sublobatum Analysis of biomarkers for bone formation in osteoblastic MC3T3-E1 cells and bone resorption in osteoclast cells derived from mouse bone marrow cells was performed to evaluate the mechanism of action. The protective activity of harpagide against bone loss was also evaluated in ovariectomized (OVX) mouse model.

RESULTS

Harpagide improved bone properties by stimulating the process of differentiation and maturation of osteoblast cells and suppressing the process of RANKL-induced differentiation of osteoclast cells. In OVX-induced bone loss mouse model, oral administration of harpagide significantly improved recovery of bone mineral density, trabecular bone volume, and trabecular number in the femur. Harpagide also prevented increase of trabecular separation and structure model index induced by OVX. Harpagide effectively inhibited the serum levels of biochemical markers of bone loss, including alkaline phosphatase, osteocalcin, C-terminal telopeptide, and tartrate-resistant acid phosphatase.

CONCLUSION

Taken together, the present study demonstrates that harpagide has a potential for prevention of bone loss in OVX mice by regulating the stimulation of osteoblast differentiation and the suppression of osteoclast formation. Therefore, these findings suggest that harpagide might serve as a bioactive compound derived from H. procumbens var. sublobatum for improvement of age-dependent bone destruction disease.

Ovariectomy-associated changes in interradicular septum and in tibia metaphysis in different observation periods in rats

In order to standardize an experimental model to study the effects of absence of ovarian hormones in maxillary bones compared with long bones, the aim of this research was to analyze the influence of ovariectomy (OVX) on rat alveolar bone and tibiae, in different observation periods. Thirty-six female rats were ovariectomized or sham operated. After 60, 90 or 120 days, the animals were sacrificed and their hemimandibles, maxillae and tibiae were removed and routinely prepared for hematoxylin and eosin staining. The percentage of bone matrix area in bone septum in the first molar furcation region, and in tibial metaphysis was calculated, and data were submitted to statistical analysis (p<0.05). As regards the histomorphometrical analysis in jaw bones, there was no statistical difference between groups, while the effects of ovariectomy on tibiae were seen as early as 60 days. According to the methods used, there was no significant influence of absence of ovarian hormones on interradicular septum of mandibular or maxillary first molars in the periods studied, despite the reduction in bone matrix area in tibia metaphysis as early as 60 days.

Effects of JSOG-6 on protection against bone loss in ovariectomized mice through regulation of osteoblast differentiation and osteoclast formation

Background

JSOG-6 is used as a traditional medicine to relieve the symptoms associated with inflammation, rheumatism, and osteoporosis in Korea. In the present study, we investigated the effects of JSOG-6 on bone loss prevention both in in vitro and in vivo as well as its underlying mechanism of action.

Methods

Protection against bone loss was assessed in an ovariectomized (OVX) mouse model. Bone microarchitecture was measured using a micro-computed tomography to detect the parameters of three-dimensional structure of a trabecular bone. Serum biomarkers were also evaluated in an OVX-induced model. Osteoclasts derived from mouse bone marrow cells (BMCs) and osteoblastic MC3T3-E1 cells were also employed to investigate the mechanism of action.

Results

Oral administration of JSOG-6 significantly increased the bone mineral density (BMD) of the femur in OVX mice in vivo. Especially, the reduced Tb.No (trabecular bone number) in the OVX group was significantly recovered by JSOG-6 treatment. The serum levels of alkaline phosphatase (ALP), osteocalcin, C-terminal telopeptide, and tartrate-resistant acid phosphatase, biomarkers of bone resorption, were significantly elevated in OVX mice, but JSOG-6 effectively inhibited the increase in OVX mice. JSOG-6 was also found to enhance the osteoblastic differentiation and maturation with the increase of the density and ALP activity, a marker of osteoblastic differentiation, as well as calcium deposition, a marker of osteoblastic maturation in MC3T3-E1 cells. The effects of JSOG-6 on osteoblastic differentiation were also associated in part with the increase of ALP and OPN mRNA expressions and the decrease of RANKL mRNA expression in MC3T3-E1 cells.

Conclusions

The findings demonstrate that JSOG-6 induced protection against bone loss in OVX mice, and its anti-osteoporotic property might be, in part, a function of the stimulation of osteoblast differentiation and the inhibition of osteoclast formation. These findings suggest that JSOG-6 might be an applicable therapeutic traditional medicine for the regulation of the osteoporotic response.

Estrogen increases the transcription of human α2-Heremans-Schmid-glycoprotein by an interplay of estrogen receptor α and activator protein-1

The expression of α2-Heremans-Schmid-glycoprotein (AHSG) was estrogen responsive in oophorectomized (OVX) osteopenic rats and HepG2 cells. Estrogen receptor α (ERα) interacted with the c-Jun/c-Fos heterodimer and indirectly associated with the -1488/-1482 activator protein-1 (AP-1) motif of the AHSG promoter. Estrogen increased c-Jun/c-Fos expression via the mitogen-activated protein kinase (MAPK) pathway.

INTRODUCTION

AHSG is a hepatic secretory protein implicated in the regulation of bone homeostasis. Serum AHSG in women has been reported to decrease after menopause and increase with estrogen therapy. The detailed regulatory mechanism of estrogen on AHSG is unclear.

METHODS

A postmenopausal osteoporosis model was generated in OVX rats. Skeletal parameters were determined by automatic biochemical analysis and dual X-ray absorptiometry. The expression of AHSG was evaluated by ELISA, real-time PCR, and Western blot. The 1.5-kb 5'-promoter region of AHSG was analyzed by serial truncation and luciferase assays. The putative -1488/-1482 AP-1 responsive element was identified by electrophoresis mobility shift assay (EMSA). Chromatin immunoprecipitation (ChIP), re-ChIP, and co-immunoprecipitation (Co-IP) were used to characterize the interaction of ERα and AP-1 at the -1488/-1482 AP-1 binding site. The MAPK pathway was evaluated using a specific inhibitor and active transfection.

RESULTS

The expression of AHSG was estrogen responsive in both OVX rats and estradiol (E2)/ERα-treated HepG2 cells. E2/ERα most prominently increased luciferase activity of a construct with a putative -1488/-1482 AP-1 binding element. ERα interacted with the c-Jun/c-Fos heterodimer and indirectly associated with the -1488/-1482 AP-1 motif of the AHSG promoter. c-Jun/c-Fos expression was increased via the MAPK pathway by E2/ERα.

CONCLUSION

Estrogen activated the transcription of AHSG through an indirect binding of ERα to the -1488/-1482 AP-1 binding element, with the c-Jun/c-Fos heterodimers.

Flaxseed enhances the beneficial effect of low-dose estrogen therapy at reducing bone turnover and preserving bone microarchitecture in ovariectomized rats

Our previous research showed greatest protection to vertebral bone mineral density and strength in ovariectomized (OVX) rats when lignan- and α-linolenic acid-rich flaxseed (FS) is combined with low-dose estrogen therapy (LD) compared with either treatment alone. This study determined the effects of combined FS+LD on serum and tissue markers of bone turnover and microarchitecture to explain our previous findings. Three-month-old OVX rats were randomized to negative control (NEG), FS, LD or FS+LD for 2 or 12 weeks, meaningful time points for determining effects on markers of bone metabolism and bone structure, respectively. Ground FS was added to the AIN-93M diet (100 g/kg diet) and LD (0.42 μg 17β-estradiol/(kg body weight·day)) was delivered by subcutaneous implant. Sham rats were included as positive control. Bone formation (e.g., osteocalcin), bone resorption (e.g., tartrate-resistant acid phosphatase-5β (TRAP-5β)), as well as osteoprotegerin (OPG) and receptor activator of nuclear factor κ-B ligand (RANKL) were analyzed from the 2-week study by commercial assays (serum) and (or) histology (vertebra). Vertebral bone microarchitecture was measured from the 12-week study using microcomputed tomography. In serum, FS+LD and LD induced lower TRAP-5β and osteocalcin, and higher OPG and OPG/RANKL ratio versus NEG and FS (p < 0.05). In vertebrae, FS+LD induced higher OPG and lower osteocalcin versus NEG (p < 0.01) and did not differ from LD and FS. FS+LD improved bone microarchitecture versus NEG, FS, and LD (p < 0.05). In conclusion, FS+LD protects bone tissue because of a reduction in bone turnover. However, elucidating the distinctive action of FS+LD on bone turnover compared with LD requires further investigation.

Methanol Extract of Euchelus asper Prevents Bone Resorption in Ovariectomised Mice Model

Marine molluscs are widely distributed throughout the world and many bioactive compounds exhibiting antiviral, antitumor, antileukemic, and antibacterial activity have been reported worldwide. The present study was designed to investigate the beneficial effect of methanol extract of Euchelus asper (EAME) on estrogen deficiency induced osteoporosis in ovariectomised mice model. Forty-two female Swiss albino mice were randomly assigned into Sham operated (Sham) group and six ovariectomised (OVX) subgroups such as OVX with vehicle (OVX); OVX with estradiol (2 mg/kg/day); OVX with EAME of graded doses (25, 50, 100, and 200 mg/kg/day). Bone turnover markers like serum alkaline phosphatase (ALP), serum acid phosphatase (ACP), serum calcium, and histological investigations of tibia and uterus were analysed. Metaphyseal DNA content of the femur bone was also studied. Antiosteoclastogenic activity of EAME was examined. Administration of EAME was able to reduce the increased bone turnover markers in the ovariectomised mice. Histomorphometric analysis revealed an increase in bone trabeculation and restoration of trabecular separation by EAME treatment. Metaphyseal DNA content of the femur of the OVX mice was increased by EAME administration. EAME also showed a potent antiosteoclastogenic behaviour. Thus, the present study reveals that EAME was able to successfully reduce the estrogen deficiency induced bone loss.

Turbo methanol extract inhibits bone resorption through regulation of T cell function

Marine organisms have bioactive potential which has tremendous pharmaceutical promise. Emerging evidence highlights the importance of the interplay between bone and the immune system of which T lymphocytes and their product act as key regulators of bone resorption. In the present investigation we have analyzed the anti-osteoporotic effect of turbo methanol extract (TME) in the reversal of bone resoprtion. Forty-two female Swiss albino mice were used and randomly assigned into sham-operated group (sham) and six ovariectomized (OVX) subgroups, i.e. OVX with vehicle (OVX) that received daily oral administration of water ad libitum; OVX with estradiol (2mg/kg/day); and OVX with different doses of TME i.e. TME 100mg/kg, TME 50mg/kg, TME 25mg/kg and TME 12.5mg/kg. Oral administration of TME or estradiol started on the second week after ovariectomy for a period of 4weeks. We observed that the administration of TME increased the trabeculation in tibia and reduced the atrophy in the uterus. TME significantly decreased the serum alkaline phosphatase (ALP) and acid phosphatase (ACP) activity in OVX mice. Micro CT analysis revealed that the TME administration preserved the bone volume, connectivity density, trabecular number, trabecular thickness and trabecular separation in OVX mice. Bone mineralization was measured in different groups of mice by Raman spectroscopy. Reversal of bone resorption was observed in TME treated group of mice. To further investigate the mechanism of action of TME, we analyzed the T lymphocyte proliferation and profiles of cytokine TNFα and sRANKL in TME treated ovariectomized mice. Decrease in the elevation of T cell subsets was observed after the supplementation with TME. The extract significantly lowered the T cell proliferation responses to mitogens, phorbol 12-myristate 13-acetate (PMA) and ionomycin (Io) and phytohemagglutinin (PHA). A marked reduction in TNFα and sRANKL secretion in serum and TNFα in cell free supernatants of activated T lymphocytes was observed upon TME administration. TME could significantly inhibit the in vitro osteoclastogenesis and the bone resorption observed using artificial calcium coated slides. Collectively, these results indicate that TME has the potential to inhibit bone resorption and may prove to be a potential candidate for the development of an anti-osteoporosis drug.

Osteoprotective effect of propranolol in ovariectomized rats: a comparison with zoledronic acid and alfacalcidol

BACKGROUND

Currently β-adrenergic receptor blockers are considered to be potential drugs under investigation for preventive or therapeutic effect in osteoporosis. However, there is no published data showing the comparative study of β-blockers with well accepted agents for the treatment of osteoporosis. To address this question, we compared the effects of propranolol with well accepted treatments like zoledronic acid and alfacalcidol in an animal model of postmenopausal osteoporosis.

METHODS

Five days after ovariectomy, 36 ovariectomized (OVX) rats were divided into 6 equal groups, randomized to treatments zoledronic acid (100 μg/kg, intravenous single dose); alfacalcidol (0.5 μg/kg, oral gauge daily); propranolol (0.1 mg/kg, subcutaneously 5 days per week) for 12 weeks. Untreated OVX and sham OVX were used as controls. At the end of treatment serum calcium and alkaline phosphatase were assayed. Femurs were removed and tested for bone density, bone porosity, bone mechanical properties and trabecular micro-architecture.

RESULTS

Propranolol showed a significant decrease in alkaline phosphatase levels and bone porosity in comparison to OVX control. Moreover, propranolol significantly improved bone density, bone mechanical properties and inhibited the deterioration of trabecular microarchitecture when compared with OVX control. The osteoprotective effect of propranolol was comparable with zoledronic acid and alfacalcidol.

CONCLUSIONS

Based on this comparative study, the results strongly suggest that propranolol can be a candidate therapeutic drug for the management of postmenopausal osteoporosis.

Effect of host sex and sex hormones on muscle-derived stem cell-mediated bone formation and defect healing

Muscle-derived stem cells (MDSCs) are known to exhibit sexual dimorphism, by donor sex, of osteogenic, chondrogenic, and myogenic differentiation potential in vitro. Moreover, host sex differences in the myogenic capacity of MDSCs in vivo are also observed. This study investigated the role of host sex and host sex hormones in MDSC-mediated bone formation and healing. Using unaltered male, castrated male, unaltered female, and ovariectomized female mice, both MDSC-mediated ectopic bone formation and cranial defect healing were examined. Male hosts, whether unaltered or castrated, form significantly larger volumes of MDSC-mediated ectopic bone than female hosts (either unaltered or ovariectomized), and no differences in ectopic bone volume were found between hosts of the same sex. In a cranial defect healing model, similar results were found-unaltered and castrated male hosts display larger volumes of bone formed when compared with unaltered and ovariectomized female hosts. However, in this healing model, some volume differences were found between hosts of the same sex. In both models, these differences were attributed to varying rates of endochondral bone formation in male and female hosts.

Oleanolic acid exerts an osteoprotective effect in ovariectomy-induced osteoporotic rats and stimulates the osteoblastic differentiation of bone mesenchymal stem cells in vitro

OBJECTIVE

Oleanolic acid (OA) and its glycosides have been reported to prevent bone loss by inhibiting the formation of osteoclasts. However, because bone formation and resorption are balanced processes in bone metabolism, no studies have described the effect of OA on osteogenesis. The aim of the present study was to evaluate the osteoprotective effect of OA in rats with ovariectomy (OVX)-induced osteoporosis and to search for the molecular targets of OA in bone mesenchymal stem cells (bMSCs).

METHODS

Two-month-old female mice that underwent OVX were treated with OA (20 mg/kg a day). After 2 weeks and after 3 months, bone mass was evaluated by micro-CT, morphometry, and immunohistochemical detection. In addition, the expression of 256 genes was measured via microarray and confirmed by real-time reverse transcription-polymerase chain reaction. The effects of OA on the activities of bMSCs were also observed in vitro using alkaline phosphatase and cell proliferation assays.

RESULTS

Micro-CT displayed only a tendency for bone loss at 2 weeks but a decrease in bone mass at 3 months after OVX. OA treatment increased osteoblast number, increasing osteocalcin and runt-related protein 2 protein levels in vivo and facilitating the osteoblastic differentiation of bMSCs in vitro at doses of 10(-6) and 10(-5) M. Gene expression profile analysis revealed that OVX caused a marked dysregulation of gene expression, especially at 2 weeks, some of which was rescued by OA. Few of these genes overlapped, but their functions were involved in the Notch signaling pathway between two phases of the osteoporotic process.

CONCLUSIONS

OA exerts an osteoprotective effect in OVX-induced osteoporotic rats and stimulates the osteoblastic differentiation of bMSCs in vitro. The molecular mechanism of this effect might be related to the Notch signaling pathway and requires further investigation.

Protective effect of egg yolk peptide on bone metabolism

OBJECTIVE

Osteoporosis is a major health problem worldwide, and most current therapy used in osteoporosis treatment acts by either increasing bone formation or decreasing bone resorption. However, the adverse effects of these therapies may preclude their long-term use. We examined the effects of egg yolk water-soluble peptide (YPEP) on bone metabolism as an alternative to current therapeutic agents in ovariectomized (OVX) rats.

METHODS

In the first step, the in vitro effects of YPEP on bone loss were determined. The proliferation, collagen content, and alkaline phosphatase activity of preosteoblastic MC3T3-E1 cells and osteoclastogenesis from bone marrow-derived precursor cells were measured. The in vivo experiment confirmed the positive effect of YPEP on bone tissue. Three-month-old female Sprague-Dawley rats were either sham operated or ovariectomized and fed commercial chow diet or 0.1% YPEP-supplemented diet for 3 month.

RESULTS

YPEP increased preosteoblastic MC3T3-E1 cell proliferation and alkaline phosphatase activity in a dose-dependent manner. Collagen content was also increased by YPEP treatment. Furthermore, YPEP potently suppressed osteoclastogenesis from bone marrow-derived precursor cells. YPEP (100 μg/mL) abolished the formation of osteoclasts positive for tartrate-resistant acid phosphatase. OVX rats supplemented with YPEP showed an osteoprotective effect, as the bone mineral density and cortical thickness in the tibia were increased compared with the OVX controls. Moreover, histological data indicate that YPEP prevented the cancellous bone loss induced by ovariectomy. None of these protective effects were observed in casein-treated rats.

CONCLUSIONS

The present study suggests that YPEP is a promising alternative to current therapeutic agents for the management of osteoporosis.

Effects of ovariectomy on bone metabolism and bone mineral density in spontaneously diabetic Torii-Lepr(fa) rats

The Spontaneously Diabetic Torii-Lepr(fa) (SDT- fa/fa) rat is a new model of obese type 2 diabetes. The female SDT-fa/fa rat shows obesity, hyperglycemia and hyperlipidemia from a young age. However, it is not known whether diabetes and estrogen deficiency can lead to bone abnormalities in the female SDT-fa/fa rat. The objective of the present study was to investigate the effects of ovariectomy (OVX) on bone metabolism and bone mineral density (BMD) in the female SDT-fa/fa rat. Female Sprague-Dawley rats were used as control animals. The BMDs of the whole tibia and fifth lumbar (L5) vertebral body were analyzed at 30 weeks after OVX. Serum osteocalcin, a bone formation marker, and urine deoxypyridinoline (DPD), a bone resorption marker, were sequentially analyzed before and at 5, 15 and 30 weeks after OVX. Serum osteocalcin and urine DPD levels were lower in SDT-fa/fa rats than in control rats before OVX. Both serum osteocalcin and urine DPD levels were elevated in control rats 5-30 weeks after OVX, but only the urine DPD levels were elevated in SDT-fa/fa rats 5-30 weeks after OVX. SDT-fa/fa rats showed a decrease in the BMDs of the whole tibia and L5 vertebral body compared with control rats. OVX decreased the BMDs of the whole tibia and L5 vertebral body in control rats, but not in SDT-fa/fa rats. These data suggest that estrogen deficiency is not a risk factor for bone loss in type 2 diabetes mellitus.

Study of the mechanisms by which Sambucus williamsii HANCE extract exert protective effects against ovariectomy-induced osteoporosis in vivo

The purpose of this study is to investigate the dose-dependent effects of SWH on bone properties and the mechanism involved in mediating the osteoprotective actions of SWH. The results indicated that SWH could improve bone properties by inhibiting the process of bone resorption and stimulating the process of bone formation.

INTRODUCTION

Our previous study showed that Sambucus williamsii HANCE (SWH) improved trabecular bone mass and cortical bone strength in ovariectomized (OVX) rats. The purpose of this study is to investigate the dose-dependent effects of SWH on bone properties and the mechanism involved in mediating the osteoprotective actions of SWH.

METHODS

Three-month-old C57BL/6J mice were fed a phytoestrogen-free diet and subjected to either ovariectomy or sham operation. OVX mice were treated with genistein (50 mg/kg), or a low (200 mg/kg), medium (500 mg/kg), or high (1,000 mg/kg) dose of SWH extract.

RESULTS

SWH could dose-dependently decrease urinary Ca excretion and increase serum Ca level in OVX mice. It could increase tibial bone mineral density and exert beneficial effects on the microarchitecture of trabecular bone in the OVX mice. SWH suppressed the ovariectomy-induced expression of Cbfa1 mRNA and cathepsin K mRNA and enhanced the ratio of OPG/RANKL mRNA expression in the tibia. In vitro study showed that SWH dramatically reduced the number of TRAP-positive cells in RANKL-induced RAW 264.7 cells.

CONCLUSIONS

The present study indicated that SWH could improve bone properties by inhibiting the process of bone resorption and stimulating the process of bone formation.

Relationship between age, skeletal site, and time post-ovariectomy on bone mineral and trabecular microarchitecture in rats

The ovariectomized (OVX) rat is widely used in osteoporosis research, but no standard model exists. The individual effects of rat age, skeletal site, and time post-ovariectomy (post-OVX) on bone have been examined. However, the relationship between them is not yet fully explored. This study examined how various combinations of rat age, skeletal site, and time post-OVX affect bone mineral and microarchitecture. The rats used were 12 (n = 28), 24 (n = 28), and 44 (n = 31) weeks old. In each age group, approximately half underwent OVX and other half underwent Sham surgeries. Bone mineral (content and density) and trabecular morphology was assessed at 2, 5, 10, 15, 20, 25, and 30 weeks post-surgery. Sites examined included the proximal tibia, spine, distal femur, and proximal femur. Overall, the proximal tibia showed the earliest and greatest differences between OVX and Sham groups. The 24-week-old group showed the best osteoporotic response. The 12-week-old group showed growth effects, whilst the 44-week-old group showed aging effects. The response of certain sites to OVX was also found to depend on the rat age used. These findings may aid in explaining discrepancies reported in the literature as well as synergistic combinations that may signify advanced conditions. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:189-196, 2011.

Erythrina variegata extract exerts osteoprotective effects by suppression of the process of bone resorption

Our previous study showed that Erythrina variegata L. (EV) inhibited bone loss and improved bone properties in ovariectomised rats. The purpose of the present study is to investigate the potential mechanism involved in mediating the osteoprotective actions of EV. Female Sprague–Dawley rats were fed a phyto-oestrogen-free diet and subjected to either ovariectomy or a sham operation. Ovariectomised rats were treated with genistein (40 mg/kg) as well as low (200 mg/kg), medium (500 mg/kg) or high (1000 mg/kg) doses of EV extract. Bone properties and mRNA expressions were evaluated by micro-computed tomography and quantitative RT-PCR, respectively. Osteoclast differentiation in RAW 264·7 cells was studied by tartrate-resistant acid phosphatase (TRAP) staining. High doses of EV could decrease urinary Ca and P excretion, maintain serum Ca and P level, and exert beneficial effects on the micro-structure and morphology of trabecular bone and cortical bone in ovariectomised rats. EV suppressed the up-regulation of cathepsin K mRNA and the down-regulation of osteoprotegrin mRNA in the tibia of ovariectomised rats. TRAP-positive cell numbers were significantly decreased in receptor activator of nuclear factor-κB ligand (RANKL)-induced RAW 264·7 cells when co-cultured with EV extracts. The present study indicated that the protective effects of EV on bone properties in ovariectomised rats are likely to be mediated by its inhibitory actions on the process of bone resorption via the suppression of osteoclast differentiation and maturation.

Dietary-induced hyperparathyroidism affects serum and gingival proinflammatory cytokine levels in rats

BACKGROUND

Poor diet and inadequate nutrition are suggested to affect the periodontium as well as impair the systemic health. This study investigated the systemic and periodontal effects of dietary-induced hyperparathyroidism (dHPT) by evaluating serum and gingival proinflammatory cytokine levels.

METHODS

Twenty-four Sprague-Dawley rats were used in the study. dHPT was induced in 12 rats by calcium/phosphorus imbalance, and 12 rats were fed a standard diet (SD). Afterward, endotoxin-induced periodontitis was induced on the right mandibular molar teeth (mmt). Four study groups were created: dHPT + mmt without periodontitis (group 1), dHPT + mmt with periodontitis (group 2), SD + mmt with periodontitis (group 3), and SD + mmt without periodontitis (group 4). Interleukin (IL)-1beta and tumor necrosis factor-alpha (TNF-alpha) levels were measured by enzyme-linked immunosorbent assay to evaluate the proinflammatory cytokine profiles. Serum cytokines were analyzed in the blood samples collected prior to periodontitis induction, whereas gingival cytokines were analyzed in the gingival supernatants of the four groups.

RESULTS

Serum cytokines were higher in dHPT rats than in SD rats (P <0.001), with a positive correlation between parathormone and the cytokines (P <0.001). Gingival cytokines were highest in group 2 and lowest in group 4 (group 2 > group 3 > group 1) (P <0.001). There was a positive correlation between parathormone and the gingival cytokines in group 1 (P <0.001 for IL-1beta; P <0.01 for TNF-alpha).

CONCLUSION

The results suggested that increased serum proinflammatory cytokine production may be a complication of dHPT, and this may affect healthy and diseased periodontia by increasing gingival proinflammatory cytokine levels.

Differential mRNA expression profiles in proximal tibia of aged rats in response to ovariectomy and low-Ca diet

Both ovariectomized animals and animals fed with Ca-depleted diets are commonly used in vivo models for the investigation of osteoporosis-related bone loss. The present study aimed to study the genomic responses of bone in aged female rats to ovariectomy and dietary Ca deficiency in these models. Aged (11 months old) Sprague-Dawley rats were subjected to bilateral ovariectomy or sham-operation and fed with diets containing different dietary Ca content (LCD, 0.1% Ca or HCD, 1.2% Ca) for 12 weeks. Serum and urine were collected for biochemical marker measurement, and tibias were collected for bone mineral density (BMD) analysis by pQCT as well as for gene expression analysis by real-time PCR. Ovariectomy increased serum N-telopeptides of bone type I collagen (NTx) levels in aged rats fed with HCD (P<0.05). In addition, ovariectomy reduced BMD and predicted bone strength of tibial proximal metaphysis in aged rats fed with either LCD or HCD. Dietary Ca deficiency did not alter serum bone-specific alkaline phosphatase (BAP) or NTx levels, but induced a loss of BMD at tibia proximal metaphysis in aged rats. Ovariectomy promoted the mRNA expression of alpha-1 type I collagen (COL), osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B ligand (RANKL); and inhibited the mRNA expression of cathepsin K and matrix metalloproteinase-9 (MMP-9) in the proximal tibia of aged rats. Low-Ca diet significantly up-regulated the mRNA expression of COL, core binding factor I (Cbfa1), OPG and carbonic anhydrase II (CAII) in proximal tibia of aged rats. Our study revealed that the genomic responses of bone in proximal tibia to ovariectomy and dietary Ca deficiency were different. The bone loss induced by ovariectomy appears to be mediated primarily by an increase in RANKL mRNA expression; whereas the induction by dietary Ca restriction might be mediated by the induction of carbonic anhydrase II expression.

Effects of voluntary wheel running on goserelin acetate-induced bone degeneration

A common treatment option for many breast and prostate cancer patients is the use of a luteinizing hormone-releasing hormone agonist such as goserelin acetate (GA) which reduces sex hormone levels. This treatment, however, is associated with bone degeneration, and exercise has been suggested as a means of preventing this side effect. Little is known about the effects of low intensity, low volume exercise on GA-induced bone loss. The purpose of this study, therefore, was to investigate the effects of voluntary wheel running on bone architecture in growing male (M) and female (F) rats receiving GA treatment. Rats received an 8-week GA treatment or placebo (CON) and were either housed in cages equipped with voluntary running wheels (WR) or remained sedentary (SED) in standard cages throughout the experimental period. Following treatments, tibiae were excised and analyzed for cortical bone (cross-sectional volume, cortical volume, marrow volume, cortical thickness) and cancellous bone (bone volume/total volume, trabecular number, trabecular thickness, trabecular spacing) using micro-computed tomography. Treatment with GA resulted in a significant reduction in running wheel distances in both sexes throughout the study period (P<0.05). GA treatment had no effect on cortical bone architecture in neither sex (P>0.05). Cancellous bone degeneration, however, was observed in M and F SED+GA (P<0.05). No significant differences were observed in M WR+GA animals in bone volume/total volume, trabecular number and trabecular spacing when compared to M SED+CON (P>0.05). In F WR+GA, trabecular thickness did not differ from that of F SED+CON (P>0.05), and trabecular spacing was found to be significantly lower than F SED+GA (P<0.05). The current report indicates that 8 weeks of GA treatment promotes cancellous bone degeneration, and voluntary wheel running provides no clear osteoprotection in growing male and female rats.

Methanolic Extract of Cuminum cyminum Inhibits Ovariectomy-Induced Bone Loss in Rats

Several animal and clinical studies have shown that phytoestrogens, plant-derived estrogenic compounds, can be useful in treating postmenopausal osteoporosis. Phytoestrogens and phytoestrogen-containing plants are currently under active investigation for their role in estrogen-related disorders. The present study deals with anti-osteoporotic evaluation of phytoestrogen-rich plant Cuminum cyminum, commonly known as cumin. Adult Sprague-Dawley rats were bilaterally ovariectomized (OVX) and randomly assigned to 3 groups (10 rats/group). Additional 10 animals were sham operated. OVX and sham control groups were orally administered with vehicle while the other two OVX groups were administered 0.15 mg/kg estradiol and 1 g/kg of methanolic extract of Cuminum cyminum fruits (MCC) in two divided doses for 10 weeks. At the end of the study blood, bones and uteri of the animals were collected. Serum was evaluated for calcium, phosphorus, alkaline phosphatase and tartarate resistant acid phosphatase. Bone density, ash density, mineral content and mechanical strength of bones were evaluated. Scanning electron microscopic (SEM) analysis of bones (tibia) was performed. Results were analyzed using ANOVA and Tukeys multiple comparison test. MCC (1 g/kg, p.o.) significantly reduced urinary calcium excretion and significantly increased calcium content and mechanical strength of bones in comparison to OVX control. It showed greater bone and ash densities and improved microarchitecture of bones in SEM analysis. Unlike estradiol it did not affect body weight gain and weight of atrophic uterus in OVX animals. MCC prevented ovariectomy-induced bone loss in rats with no anabolic effect on atrophic uterus. The osteoprotective effect was comparable with estradiol.

Supraphysiological testosterone enanthate administration prevents bone loss and augments bone strength in gonadectomized male and female rats

High-dose testosterone enanthate (TE) may prevent hypogonadism-induced osteopenia. For this study, 3-mo-old male and female Fisher SAS rats underwent sham surgery, gonadectomy (GX), or GX plus 28 days TE administration (7.0 mg/wk). GX reduced serum sex hormones (i.e., testosterone, dihydrotestosterone, and estradiol) (P < 0.05) in both sexes and bone concentrations of testosterone (males only), and estradiol (females only). GX also elevated urine deoxypyridinoline/creatinine in both sexes and serum osteocalcin (females only), findings that are consistent with high-turnover osteopenia. GX reduced cancellous bone volume (CBV) and increased osteoid surfaces in tibia of both sexes. GX males also experienced reduced trabecular number and width and increased trabecular separation, whereas GX females experienced increased osteoblast and osteoid surfaces. Bone biomechanical characteristics remained unaffected by GX, except that femoral stiffness was reduced in females. In contrast, TE administration to GX rats elevated serum and bone androgens to supraphysiological concentrations in both sexes but altered neither serum nor bone estradiol in males. Additionally, TE did not prevent GX-induced reductions in serum or bone estradiol in females. TE also reduced markers of high-turnover osteopenia in both sexes. In males, TE prevented GX-induced changes in trabecular number and separation, CBV, and osteoid surfaces while diminishing osteoblast and osteoclast surfaces; however, these changes were not fully prevented in females. In both sexes, TE increased femoral length and femoral maximal strength to above that of Sham and GX animals while preventing the loss of femoral stiffness in females. In conclusion, TE administration appears protective of cancellous bone in male rats and augments cortical bone strength in both sexes.

Protective effect of green tea polyphenols on bone loss in middle-aged female rats

Recent studies have suggested that green tea polyphenols (GTP) are promising agents for preventing bone loss in women. Findings that GTP supplementation resulted in increased urinary GTP concentrations and bone mass via an increase of antioxidant capacity and/or a decrease of oxidative stress damage suggest a significant role of GTP in bone health of women.

INTRODUCTION

Recent studies suggested that green tea polyphenols (GTP) are promising agents for preventing bone loss in women. However, the mechanism related to the possible protective role of GTP in bone loss is not well understood.

METHODS

This study evaluated bioavailability, mechanisms, bone mass, and safety of GTP in preventing bone loss in middle-aged rats without (sham, SH) and with ovariectomy (OVX). A 16-week study of 2 (SH vs. OVX) x 3 (no GTP, 0.1% GTP, and 0.5% GTP in drinking water) factorial design using 14-month-old female rats (n = 10/group) was performed. An additional 10 rats in baseline group were euthanized at the beginning of study to provide baseline parameters.

RESULTS

There was no difference in femur bone mineral density between baseline and the SH+0.5% GTP group. Ovariectomy resulted in lower values for liver glutathione peroxidase activity, serum estradiol, and bone mineral density. GTP supplementation resulted in increased urinary epigallocatechin and epicatechin concentrations, liver glutathione peroxidase activity and femur bone mineral density, decreased urinary 8-hydroxy-2'-deoxyguanosine and urinary calcium levels, but no effect on serum estradiol and blood chemistry levels.

CONCLUSION

We conclude that a bone-protective role of GTP may contribute to an increase of antioxidant capacity and/or a decrease of oxidative stress damage.