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

Formulation development and in vitro-in vivo assessment of protransfersomal gel of anti-resorptive drug in osteoporosis treatment

Osteoporosis is a major cause of morbidity, mortality, and economic burden worldwide. Despite being an effective in combating the bone-deteriorating disorders, bisphosphonates have several shortcomings including poor and variable bioavailability, low permeability, high toxicity, etc. In this study, we developed and optimized protransfersome formulation for the drug risedronate sodium (RIS-Na) with the goal of enhancing its bioavailability and hence patient compliance. Phase separation coacervation technique was utilized for development of optimized formulation. Optimization was achieved by using three-factor, three-level Box-Behnken design combined with Response Surface Methodology (RSM). This enabled us to decipher the effect of 3 independent variables (Phospholipid, Tween-80 and Sodium Deoxycholate) on three dependent parameters (entrapment efficiency, vesicle size and transdermal flux). Optimized formulation was further evaluated for pharmacokinetic and pharmacodynamic parameters. Smooth, spherical protransfersomes with a size of 260 ± 18 nm, having entrapment efficiency and flux of 80.4 ± 4.90% and 8.41 ± 0.148 μg/cm²/h, respectively were prepared. Ex vivo studies revealed a shorter lag time of 1.21 ± 0.18 h and higher flux associated with transdermal formulation. CLSM analysis further revealed better drug penetration (220 μm) through the skin in case of protransfersomes as compared to drug solution (72 μm). Additionally, biomechanical, biochemical, and histo-pathological studies further validated the results. Thus, it was concluded that protransfersome formulation has a great potential in providing better therapeutic efficacy of risedronate than its conventional counterpart.

The Effects of NPY1 Receptor Antagonism on Intervertebral Disc and Bone Changes in Ovariectomized Rats

STUDY DESIGN

Basic science.

OBJECTIVE

To compare the effects of a neuropeptide Y1 receptor antagonist (NPY-1RA) to estrogen on maintaining vertebral bone microarchitecture and disc height in a rat model of menopause.

METHODS

This study was an institutional animal care approved randomized control study with 104 ovariectomized rats and 32 intact control animals. Comparison of disc height, trabecular bone, body weights, circulating levels of NPY and estrogen, and distribution of Y1 receptors in the intervertebral disc in an established rodent osteoporotic model were made at baseline and after 2, 4, and 8 weeks after receiving either an implant containing estrogen or an antagonist to the neuropeptide Y1 receptor. Data was compared statistically using One-way analysis of variance.

RESULTS

Circulating levels of estrogen increased and NPY decreased following estrogen replacement, with values comparable to ovary-intact animals. NPY-1RA-treated animals had low estrogen and high NPY circulating levels and were similar to ovariectomized control rats. Both NPY-1RA and estrogen administration were able reduce, menopause associated weight gain. NPY-1RA appeared to restore bone formation and maintain disc height, while estrogen replacement prevented further bone loss.

CONCLUSION

NPY-1RA in osteoporotic rats activates osteoblast production of bone and decreased marrow and body fat more effectively than estrogen replacement when delivered in similar concentrations. Annulus cells had NPY receptors, which may play a role in disc nutrition, extracellular matrix production, and pain signaling cascades.

Ferulic acid attenuates osteoporosis induced by glucocorticoid through regulating the GSK-3β/Lrp-5/ERK signalling pathways

Objective

To evaluate in-vivo and in-vitro effects of ferulic acid (FA) on glucocorticoid-induced osteoarthritis (GIO) to establish its possible underlying mechanisms.

Methods

The effects of FA on cell proliferation, cell viability (MTT assay), ALP activity, and mineralization assay, and oxidative stress markers (ROS, SOD, GSH LDH and MDA levels) were investigated by MC3T3-E1 cell line. Wistar rats received standard saline (control group) or dexamethasone (GC, 2 mg-1 kg) or DEX+FA (50 and 100 mg-1 kg) orally for 8 weeks. Bone density, micro-architecture, bio-mechanics, bone turnover markers and histo-morphology were determined. The expression of OPG, RANKL, osteogenic markers, and other signalling proteins was assessed employing quantitative RT-PCR and Western blotting.

Results

The findings indicated the elevation of ALP mRNA expressions, osteogenic markers (Runx-2, OSX, Col-I, and OSN), and the β-Catenin, Lrp-5 and GSK-3β protein expressions. FA showed the potential to increase MC3T3-E1 cell differentiation, proliferation, and mineralization. FA increased oxidative stress markers (SOD, MDA, and GSH) while decreasing ROS levels and lactate dehydrogenase release in GIO rats. The OPG/RANKL mRNA expression ratio was increased by FA, followed by improved GSK-3β and ERK phosphorylation with enhanced mRNA expressions of Lrp-5 and β-catenin.

Conclusion

These findings showed that FA improved osteoblasts proliferation with oxidative stress suppression by controlling the Lrp-5/GSK-3β/ERK pathway in GIO, demonstrating the potential pathways involved in the mechanism of actions of FA in GIO therapy.

Driving β2- While Suppressing α-Adrenergic Receptor Activity Suppresses Joint Pathology in Inflammatory Arthritis

Objective

Hypersympathetic activity is prominent in rheumatoid arthritis, and major life stressors precede onset in ~80% of patients. These findings and others support a link between stress, the sympathetic nervous system and disease onset and progression. Here, we extend previous research by evaluating how selective peripherally acting α/β2-adrenergic drugs affect joint destruction in adjuvant-induced arthritis.

Methods

Complete Freund's adjuvant induced inflammatory arthritis in male Lewis rats. Controls received no treatment. Arthritic rats then received vehicle or twice-daily treatment with the α-adrenergic antagonist, phentolamine (0.5 mg/day) and the β2-adrenergic agonist, terbutaline (1200 µg/day, collectively named SH1293) from day (D) of disease onset (D12) through acute (D21) and severe disease (D28). Disease progression was assessed in the hind limbs using dorsoplantar widths, X-ray analysis, micro-computed tomography, and routine histology on D14, D21, and D28 post-immunization.

Results

On D21, SH1293 significantly attenuated arthritis in the hind limbs, based on reduced lymphocytic infiltration, preservation of cartilage, and bone volume. Pannus formation and sympathetic nerve loss were not affected by SH1293. Bone area and osteoclast number revealed high- and low-treatment-responding groups. In high-responding rats, treatment with SH1293 significantly preserved bone area and decreased osteoclast number, data that correlated with drug-mediated joint preservation. SH1293 suppressed abnormal bone formation based on reduced production of osteophytes. On D28, the arthritic sparing effects of SH1293 on lymphocytic infiltration, cartilage and bone sparing were maintained at the expense of bone marrow adipocity. However, sympathetic nerves were retracted from the talocrural joint.

Conclusion and Significance

Our findings support a significant delay in early arthritis progression by treatment with SH1293. Targeting sympathetic neurotransmission may provide a strategy to slow disease progression.

Biomechanical and Biochemical Analyses of the Effects of Propranolol on the Osseointegration of Implants

This study aimed to investigate the effects of systemic propranolol on the osseointegration of titanium implants. After the surgical insertion of titanium implants into the metaphyseal part of the tibiae of rats, the rats were randomly divided into three equal groups: the control (n = 8), propranolol dosage-1 (PRP-1) (n = 8), and propranolol dosage-2 (PRP-2) (n = 8) groups. In the control group, the rats received no further treatment during the 4-week experimental period after the surgery. After the surgical insertion of the implants, the rats in the PRP-1 and PRP-2 groups were given 5 mg/kg and 10 mg/kg propranolol, respectively, every 3 days for the 4-week experimental period. After the experimental period, the rats were euthanized. Blood sera were collected for biochemical analysis, and the implants and surrounding bone tissues were used for the biomechanical reverse torque analysis. One-way ANOVA and Tukey's honest significant difference test were used for statistical analysis. The student t-test was used to analyze the data obtained from the tests and the controls. There were no significant differences in the reverse torque analysis results and the biochemical parameters (alkaline phosphatase, calcium, and phosphorus) of the groups (P > 0.05). Alkaline phosphatase was, however, found to be higher in test animals compared to the controls (P < 0.05). Also, propranolol did not biomechanically affect the osseointegration of titanium implants, while alkaline phosphatase activity was higher in the test animals.

Ferulic acid, a natural polyphenol, protects against osteoporosis by activating SIRT1 and NF-κB in neonatal rats with glucocorticoid-induced osteoporosis

Osteoporosis is a chronic disease whose symptoms include a reduction in bone strength, osteopenia, and damage to the bone microstructure. Ferulic acids are natural polyphenols present in various fruits that suppress the fusion and apoptosis of mature osteoclasts. Rats were divided into sham, control (osteoporosis), 10 mg/kg body weight ferulic acid, 20 mg/kg body weight ferulic acid, and 30 mg/kg body weight ferulic acid treatment groups. Osteoporosis was induced in neonatal by administration of dexamethasone (glucocorticoids). Bone mineral density (BMD), osteocalcin and alkaline phosphatase (ALP) levels, bone mechanical parameters, and mRNA and protein levels of sirtuin1 (SIRT1) and nuclear factor kappa-B (NF-κB) in the osteoporotic neonatal rats were assessed. Histopathological analysis was also conducted. Treatment with 20 and 30 mg/kg body weight ferulic acid increased BMD by 25% and 141.7%, respectively, but reduced ALP and osteocalcin levels. Furthermore, treatment with 20 or 30 mg/kg body weight ferulic acid significantly reduced the pixel intensity and significantly increased the peak load and ultimate stiffness. Ferulic acid significantly increased the mRNA and protein levels of SIRT1 and reduced those of NF-κB. Finally, the histopathological analysis showed that ferulic acid increased BMD. In summary, ferulic acid exhibited protective effects against osteoporosis in neonatal rats.

Elucidating the role of size of hydroxyl apatite particles toward the development of competent antiosteoporotic bioceramic materials: In vitro and in vivo studies

Osteoporosis caused by overdose of steroids is one of the major concerns for the orthopedic surgeons. Current therapeutic strategies offer limited success due to their inability to regenerate damaged bone at osteoporosis site. Therefore, there is an urgent need to develop a material having bone regeneration ability and also, ability to cure osteoporosis simultaneously. In this work, nanosized and microsized hydroxyl apatite (HAp) particles doped with europium (Eu) were prepared for diagnostic and therapeutic applications in biomedical engineering. Particles were characterized by X-ray diffraction to confirm the formation of HAp phase and transmission electron microscopy technique has been used to explore the size of microparticle and nanoparticle. In vitro release of antibiotic drug and degradation behavior in two different pHs of phosphate buffered saline was checked. Controlled drug release behavior and conversion of degraded ions into HAp is estimated by Higuchi's and 3D diffusion model, respectively. Osteoporosis was induced in 36 female Wistar rats by administering dexamethasone once a week for four consecutive weeks. Rats were treated with different doses of nano-HAp (25, 50, and 100 μg/kg intravenous single dose) and single dose of microsized HAp (100 μg/kg). After treatment, authors have evaluated sensitive biochemical markers of bone in serum. Continuous improvement in ultimate stiffness and Young's modulus of femur shaft of rats was observed with the increase in the dose of nano-HAp from 25 to 100 μg/kg. Results strongly suggest that europium-doped nano-HAp is more effective for treating severe osteoporosis in humans. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1723-1735, 2019.

Androgen Receptor in Neurons Slows Age-Related Cortical Thinning in Male Mice

Androgens via the androgen receptor (AR) are required for optimal male bone health. The target cell(s) for the effects of androgens on cortical bone remain(s) incompletely understood. In females, estrogen receptor alpha in neurons is a negative regulator of cortical and trabecular bone. Whether neuronal AR regulates bone mass in males remains unexplored. Here, we inactivated AR in neurons using a tamoxifen-inducible CreERT2 under the control of the neuronal promoter Thy1. Tamoxifen induced a 70% to 80% reduction of AR mRNA levels in Thy1-CreERT2-positive brain regions cerebral cortex and brainstem as well as in the peripheral nervous tissue of male neuronal AR knockout (N-ARKO) mice. Hypothalamic AR mRNA levels were only marginally reduced and the hypothalamic-pituitary-gonadal axis remained unaffected, as determined by normal levels of serum testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH). In contrast to orchidectomy, deletion of neuronal AR did not alter body weight, body composition, hindlimb muscle mass, grip strength, or wheel running. MicroCT analysis of the femur revealed no changes in bone accrual during growth in N-ARKO mice. However, 36- and 46-week-old N-ARKO mice displayed an accelerated age-related cortical involution, namely a more pronounced loss of cortical thickness and strength, which occurred in the setting of androgen sufficiency. Neuronal AR inactivation decreased the cancellous bone volume fraction in L₅ vertebra but not in the appendicular skeleton of aging mice. MicroCT findings were corroborated in the tibia and after normalization of hormonal levels. Serum markers of bone turnover and histomorphometry parameters were comparable between genotypes, except for a 30% increase in osteoclast surface in the trabecular compartment of 36-week-old N-ARKO mice. Cortical bone loss in N-ARKO mice was associated with an upregulation of Ucp1 expression in brown adipose tissue, a widely used readout for sympathetic tone. We conclude that androgens preserve cortical integrity in aging male mice via AR in neurons. © 2018 American Society for Bone and Mineral Research.

Development and characterization of a nanoemulsion containing propranolol for topical delivery

BACKGROUND

Propranolol (PPN) is a therapeutic option for the treatment of infantile hemangiomas. This study aimed at the development of nanoemulsion (NE) containing 1% PPN, characterization of the system, and safety studies based on ex vivo permeation, cytotoxicity, and biodistribution in vivo.

METHODS

The formulation was developed and characterized in relation to the droplet size, polydispersity index (PDI), pH, zeta potential, and electronic microscopy. Ex vivo permeation studies were used to evaluate the cutaneous retention of PPN in the epidermis and dermis. Cytotoxicity studies were performed in fibroblasts, macrophages, and keratinocytes. In vivo biodistribution assay of the formulations was performed by means of labeling with technetium-99m.

RESULTS

NE1 exhibited droplet size of 26 nm, PDI <0.4, pH compatible with the skin, and zeta potential of -20 mV, which possibly contributes to the stability. Electron microscopy showed that the NE presented droplets of nanometric size and spherical shape. NE1 provided excellent stability for PPN. In the ex vivo cutaneous permeation assay, the NE provided satisfactory PPN retention particularly in the dermis, which is the site of drug action. In addition, NE1 promoted cutaneous permeation of the PPN in small amount. In vivo biodistribution showed that the radiolabeled formulation remained in the skin and a small amount reached the bloodstream. NE1 presented low cytotoxicity to fibroblasts, macrophages, and keratinocytes in the concentrations evaluated in the cytotoxicity assay.

CONCLUSION

We concluded that the formulation is safe for skin administration; however, cutaneous irritation studies should be performed to confirm the safety of the formulation before clinical studies in patients with infantile hemangiomas.

The role of propranolol as a radiosensitizer in gastric cancer treatment

Purpose

The National Comprehensive Cancer Network guidelines indicate that radiotherapy in gastric cancer shows limited effectiveness at reducing the growth of gastric cancer. Therefore, enhancing the sensitivity and effect of radiotherapy with propranolol, a β-adrenoceptor antagonist, could reduce tumor growth. The role of propranolol as a radiosensitizer has not been adequately studied; therefore, the purpose of the present study is to evaluate the effect of propranolol as a radiosensitizer against gastric cancer in vivo.

Methods

Sixty-four male nude mice bearing tumor xenografts were randomly divided into four groups. Cell culture was performed using the human gastric adenocarcinoma cell line SGC-7901. Mice with tumor xenografts were treated with propranolol, isoproterenol, and radiation. The data for tumor weight and volume were obtained for statistical analyses. Furthermore, the expression levels of COX-2, NF-κB, VEGF, and EGFR were examined using immunohistochemical techniques and Western blotting.

Results

The growth in the volume and weight of the tumor was lower in mouse models treated with propranolol and radiation therapy compared to the other groups. Decreased expression of NF-κB was also observed in treatment groups where both propranolol and radiation were used, leading to the reduction of COX-2, EGFR, and VEGF expression compared to that in the other groups.

Conclusion

The present study indicated that propranolol potentiates the antitumor effects of radiotherapy in gastric cancer by inhibiting NF-κB expression and its downstream genes: VEGF, EGFR, and COX-2.

Protective effects of resveratrol on osteoporosis via activation of the SIRT1-NF-κB signaling pathway in rats

The aim of the present study was to determine the protective effects of resveratrol on a rat model of osteoporosis and examine the associated mechanisms of its action. Rats were randomized into the following groups: Control, osteoporosis, osteoporosis + low-dose resveratrol, osteoporosis + middle-dose resveratrol and osteoporosis + high-dose resveratrol groups. Resveratrol treatment was administered 7 days after surgery for 8 weeks. ELISA assay was used to analyze alkaline phosphatase (ALP) and osteocalcin (OC) protein levels. Western blotting was performed to assess the protein expression of sirtuin 1 (SIRT1), nuclear factor (NF)-κB and NF-κB inhibitor (IkB) α. In the present study, the results indicated that resveratrol markedly improved the bone mineral density value, femoral porosity and bone mechanical tests in osteoporosis rats. Administration of resveratrol significantly decreased the serum levels of ALP and OC in rats with osteoporosis. Finally, treatment with resveratrol significantly promoted the protein expression of SIRT1, suppressed NF-κB and activated the IkBα protein expression in rats with osteoporosis. In conclusion, treatment with resveratrol significantly improved the final body weight of the osteoporosis rats via the SIRT1-NF-κB signaling pathway. The present study suggested that resveratrol exerted a protective effect on osteoporosis through activation of the SIRT1-NF-κB signaling pathway in rats.

Novel therapeutic intervention for osteoporosis prepared with strontium hydroxyapatite and zoledronic acid: In vitro and pharmacodynamic evaluation

Osteoporosis therapeutics has been monopolized mainly by bisphosphonates, which are potent anti-osteoporotic drugs, while they do not promote bone formation or replenish the already resorbed bone. Although strontium substituted hydroxyapatite (SrHA) has been proclaimed to improve bone properties in an osteoporotic animal model, there is no published data on direct delivery of SrHA nanoparticles by bisphosphonate-like zoledronic acid (ZOL) to the bone. Therefore, this study was designed to investigate the potential of using SrHA/ZOL nanoparticle-based drug formulation in an ovariectomized rat model of postmenopausal osteoporosis. SrHA and SrHA/ZOL nanoparticles were prepared and characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Twelve weeks after ovariectomy, rats were treated with either single intravenous dose of SrHA/ZOL (100, 50 or 25μg/kg); ZOL (100μg/kg); or SrHA (100μg/kg). Saline-treated OVX and SHAM-OVX groups served as controls. The energy-dispersive X-ray (EDX) microanalysis of bone specimen obtained from SrHA/ZOL groups yielded range between 64.3±6.7 to 66.9±6.8 of calcium weight (wt) % and 1.64±0.6 to 1.74±0.8 of calcium/phosphorus (Ca/P) ratio which was significantly higher when compared with 39.7±9.3 calcium and 1.30±0.2 Ca/P ratio for OVX group. Moreover, the strontium wt% in SrHA/ZOL group (between 3.1±0.5 and 6.8±0.4) was significantly higher than SrHA group (1.8±0.9). These results confirmed targeted delivery of SrHA nanoparticles by ZOL to the bone. Therapy with SrHA/ZOL showed significant improvements in trabecular bone microarchitecture and mechanical strength as compared to ZOL or SrHA (p<0.05). Moreover, treatment with SrHA/ZOL significantly precluded an increase in serum bone-specific alkaline phosphatase and tartrate-resistant acid phosphatase than either ZOL or SrHA (p<0.05). These results strongly implicate that SrHA/ZOL nanoparticle-based drug formulation showed better efficacy at a much lower dose of ZOL. SrHA/ZOL drug formulation has a therapeutic advantage over ZOL or SrHA monotherapy for experimental osteoporosis.

Structure Model Index Does Not Measure Rods and Plates in Trabecular Bone

Structure model index (SMI) is widely used to measure rods and plates in trabecular bone. It exploits the change in surface curvature that occurs as a structure varies from spherical (SMI = 4), to cylindrical (SMI = 3) to planar (SMI = 0). The most important assumption underlying SMI is that the entire bone surface is convex and that the curvature differential is positive at all points on the surface. The intricate connections within the trabecular continuum suggest that a high proportion of the surface could be concave, violating the assumption of convexity and producing regions of negative differential. We implemented SMI in the BoneJ plugin and included the ability to measure the amounts of surface that increased or decreased in area after surface mesh dilation, and the ability to visualize concave and convex regions. We measured SMI and its positive (SMI(+)) and negative (SMI(-)) components, bone volume fraction (BV/TV), the fraction of the surface that is concave (CF), and mean ellipsoid factor (EF) in trabecular bone using 38 X-ray microtomography (XMT) images from a rat ovariectomy model of sex steroid rescue of bone loss, and 169 XMT images from a broad selection of 87 species' femora (mammals, birds, and a crocodile). We simulated bone resorption by eroding an image of elephant trabecule and recording SMI and BV/TV at each erosion step. Up to 70%, and rarely <20%, of the trabecular surface is concave (CF 0.155-0.700). SMI is unavoidably influenced by aberrations induced by SMI(-), which is strongly correlated with BV/TV and CF. The plate-to-rod transition in bone loss is an erroneous observation resulting from the close and artifactual relationship between SMI and BV/TV. SMI cannot discern between the distinctive trabecular geometries typical of mammalian and avian bone, whereas EF clearly detects birds' more plate-like trabecule. EF is free from confounding relationships with BV/TV and CF. SMI results reported in the literature should be treated with suspicion. We propose that EF should be used instead of SMI for measurements of rods and plates in trabecular bone.

[Additive effect of zoledronic acid and alfacalcidol in the treatment of disuse osteoporosis in rats]

OBJECTIVES

Disuse by bed rest, limb immobilization or space flight causes rapid bone loss. We conducted the present study to investigate the therapeutic effects of zoledronic acid (ZOL), alone and in combination with alfacalcidol (ALF) in a rat model of disuse osteoporosis.

METHODS

In the present study, 3-month-old male Wistar rats had their right hind-limb immobilized (RHLI) for 10 weeks to induce osteopenia, then were divided into four groups: 1- RHLI positive control; 2- RHLI plus ZOL (50 μg/kg, i.v. single dose); 3- RHLI plus ALF (0.5 μg/kg, oral gauge daily); 4- RHLI plus ALF (0.5 μg/kg, oral gauge daily) plus ZOL (50 μg/kg, i.v. single dose) for another 10 weeks. One group of non-immobilized rats was used as negative control. At the end of the treatment, the femurs were removed and tested for bone porosity, bone mechanical properties, and bone dry and ash weight.

RESULTS

Combination therapy with ZOL plus ALF was more effective in decreasing bone porosity than each drug administered as monotherapy in RHLI rats. With respect to improvement in the mechanical strength of the femoral mid-shaft, the combination treatment of ZOL plus ALF was more effective than each drug administered as a monotherapy. Moreover, combination therapy using ZOL plus ALF was more effective in improving dry bone and ash weight, than single-drug therapy using ZOL or ALF in RHLI rats.

CONCLUSIONS

These data suggest that combination therapy with ZOL plus ALF represents a potentially useful therapeutic option for the treatment of disuse osteoporosis.

Additive effects of zoledronic acid and propranolol on bone density and biochemical markers of bone turnover in osteopenic ovariectomized rats

OBJECTIVES

The present study was designed to investigate further the efficacy and safety of zoledronic acid (ZOL) and propranolol (PRO) as monotherapy and combination therapy in a rat model of postmenopausal osteoporosis.

METHODS

Female Wistar rats were ovariectomized (OVX) or sham-operated at 3 months of age. Twelve weeks post-surgery, rats were randomized into six groups: (1) sham + vehicle; (2) OVX + vehicle; (3) OVX + ZOL (100 μg/kg, i.v. single dose); (4) OVX + ZOL (50 μg/kg, i.v. single dose); (5) OVX + PRO (0.1 mg/kg, s.c. 5 days per week); (6) OVX + ZOL (50 μg/kg, i.v. single dose) + PRO (0.1 mg/kg, s.c. 5 days per week) for 12 weeks. After treatment, femurs were tested for bone density, porosity and trabecular micro-architecture. Biochemical markers in serum and urine were also determined.

RESULTS

Combined treatment with ZOL plus PRO corrected decrease in serum calcium and increase in serum alkaline phosphatase and tartarate resistant acid phosphatase level better than single-drug therapy using ZOL or PRO. Moreover, combined treatment with ZOL plus PRO corrected increase in urine calcium, phosphorous and creatinine level better than single-drug therapy using ZOL or PRO. Combination therapy using ZOL plus PRO also preserved the trabecular micro-architecture and cortical bone porosity.

CONCLUSION

These data suggest that combined treatment with ZOL plus PRO could be more effective approach for treating severe osteoporosis in humans.

Effect of combined treatment with zoledronic acid and propranolol on mechanical strength in an rat model of disuse osteoporosis

OBJECTIVES

A model that uses right hind-limb unloading of rats is used to study the consequences of skeletal unloading during various conditions like space flights and prolonged bed rest in elderly. This study was aimed to investigate the additive effects of antiresorptive agent zoledronic acid (ZOL), alone and in combination with propranolol (PRO) in a rat model of disuse osteoporosis.

METHODS

In the present study, 3-month-old male Wistar rats had their right hind-limb immobilized (RHLI) for 10 weeks to induce osteopenia, then were randomized into four groups: 1- RHLI positive control, 2- RHLI plus ZOL (50 μg/kg, i.v. single dose), 3- RHLI plus PRO (0.1mg/kg, s.c. 5 days per week), 4- RHLI plus PRO (0.1mg/kg, s.c. 5 days per week) plus ZOL (50 μg/kg, i.v. single dose) for another 10 weeks. One group of non-immobilized rats was used as negative control. At the end of treatment, the femurs were removed and tested for bone porosity, bone mechanical properties, and bone dry and ash weight.

RESULTS

With respect to improvement in the mechanical strength of the femoral mid-shaft, the combination treatment with ZOL plus PRO was more effective than ZOL or PRO monotherapy. Moreover, combination therapy using ZOL plus PRO was more effective in improving dry bone weight and preserved the cortical bone porosity better than monotherapy using ZOL or PRO in right hind-limb immobilized rats.

CONCLUSIONS

These data suggest that this combined treatment with ZOL plus PRO should be recommended for the treatment of disuse osteoporosis.

Zoledronic acid in combination with alfacalcidol has additive effects on trabecular microarchitecture and mechanical properties in osteopenic ovariectomized rats

BACKGROUND

We conducted the present study to investigate the therapeutic effects of the antiresorptive agent zoledronic acid (ZOL), alone and in combination with alfacalcidol (ALF), in a rat model of postmenopausal osteoporosis.

METHODS

Female Wistar rats were ovariectomized (OVX) or sham-operated at 3 months of age. Twelve weeks post surgery, rats were randomized into six groups: (1) sham + vehicle, (2) OVX + vehicle, (3) OVX + ZOL (100 μg/kg, i.v. single dose), (4) OVX + ZOL (50 μg/kg, i.v. single dose), (5) OVX + ALF (0.5 μg/kg, oral gauge daily) and (6) OVX + ZOL (50 μg/kg, i.v. single dose) + ALF (0.5 μg/kg, oral gauge daily) for 12 weeks. After treatment, we evaluated the mechanical properties of the lumbar vertebra and femoral mid-shaft. Femurs were also tested for bone density, porosity and trabecular micro-architecture. Biochemical markers in serum and urine were also determined.

RESULTS

With respect to improvement in the mechanical strength of the lumbar spine and the femoral mid-shaft, the combination treatment of ZOL and ALF was more effective than each administered as a monotherapy. Moreover, combination therapy using ZOL and ALF preserved the trabecular micro-architecture and cortical bone porosity. Furthermore, the combination treatment of ZOL and ALF corrected the decrease in serum calcium and increase in serum alkaline phosphatase and the tartarate-resistant acid phosphatase level better than single-drug therapy using ZOL or ALF in OVX rats. In addition, the combination treatment of ZOL and ALF corrected the increase in urine calcium, phosphorous and creatinine levels better than single-drug therapy using ZOL or ALF in OVX rats.

CONCLUSIONS

These data suggest that the combination treatment of ZOL and ALF has a therapeutic advantage over each monotherapy for the treatment of osteoporosis.

Japanese medaka: a non-mammalian vertebrate model for studying sex and age-related bone metabolism in vivo

Background

In human, a reduction in estrogen has been proposed as one of the key contributing factors for postmenopausal osteoporosis. Rodents are conventional models for studying postmenopausal osteoporosis, but the major limitation is that ovariectomy is needed to mimic the estrogen decline after menopause. Interestingly, in medaka fish (Oryzias latipes), we observed a natural drop in plasma estrogen profile in females during aging and abnormal spinal curvature was apparent in old fish, which are similar to postmenopausal women. It is hypothesized that estrogen associated disorders in bone metabolism might be predicted and prevented by estrogen supplement in aging O. latipes, which could be corresponding to postmenopausal osteoporosis in women.

Principal findings

In O. latipes, plasma estrogen was peaked at 8 months old and significantly declined after 10, 11 and 22 months in females. Spinal bone mineral density (BMD) and micro-architecture by microCT measurement progressively decreased and deteriorated from 8 to 10, 12 and 14 months old, which was more apparent in females than the male counterparts. After 10 months old, O. latipes were supplemented with 17α-ethinylestradiol (EE2, a potent estrogen mimic) at 6 and 60 ng/mg fish weight/day for 4 weeks, both reduction in spinal BMD and deterioration in bone micro-architecture were significantly prevented. The estrogenic effect of EE2 in O. latipes was confirmed by significant up-regulation of four key estrogen responsive genes in the liver. In general, bone histomorphometric analyses indicated significantly lowered osteoblasts and osteoclasts numbers and surfaces on vertebrae of EE2-fed medaka.

Significance

We demonstrate osteoporosis development associated with natural drop in estrogen level during aging in female medaka, which could be attenuated by estrogen treatment. This small size fish is a unique alternative non-mammalian vertebrate model for studying estrogen-related molecular regulation in postmenopausal skeletal disorders in vivo without ovariectomy.

The combination therapy with zoledronic Acid and propranolol improves the trabecular microarchitecture and mechanical property in an rat model of postmenopausal osteoporosis

We conducted the present study to investigate the therapeutic effects of propranolol (PRO), alone and in combination with the antiresorptive agent ZOL, in a rat model of postmenopausal osteoporosis. Female Wistar rats were OVX or sham-operated at 3 months of age. Twelve weeks after surgery, rats were randomized into six groups: (1) sham + vehicle, (2) OVX + vehicle, (3) OVX + ZOL (100  μ g/kg, i.v. single dose), (4) OVX + ZOL (50  μ g/kg, i.v. single dose), (5) OVX + PRO (0.1 mg/kg, s.c. 5 days per week), and (6) OVX + ZOL (50  μ g/kg, i.v. single dose) + PRO (0.1 mg/kg, s.c. 5 days per week) for 12 weeks. At the end of treatment study, various bone parameters were evaluated. With respect to improvement in the mechanical strength of the lumbar spine and the femoral mid-shaft, the combination treatment of ZOL and PRO was more effective than each drug administered as a monotherapy. Moreover, combination therapy using ZOL and PRO preserved the trabecular microarchitecture better than single-drug therapy using ZOL or PRO in OVX rats. These data suggest that combination therapy with ZOL plus PRO represents a potentially useful therapeutic option for patients with osteoporosis.

Prophylactic Effects of Propranolol versus the Standard Therapy on a New Model of Disuse Osteoporosis in Rats

Disuse by bed rest, limb immobilization, or space flight causes rapid bone loss by arresting bone formation and accelerating bone resorption. Propranolol (a non-selective β-adrenergic antagonist) has been shown to improve bone properties by increasing bone formation and decreasing bone resorption in an ovariectomy-induced rat model. However, no studies have yet compared the osteoprotective properties of propranolol with well-accepted therapeutic interventions for the treatment and prevention of immobilization/disuse osteoporosis. To clarify this, we investigated the effects of propranolol compared with zoledronic acid and alfacalcidol in a new animal model of immobilization/disuse osteoporosis. Three-month-old male Wistar rats were divided into five groups with six animals in each group: (1) immobilized (IMM) control; (2) normal control; (3) IMM + zoledronic acid (50 μg/kg, intravenous single dose); (4) IMM + alfacalcidol (0.5 μg/kg, per oral daily); (5) IMM + propranolol (0.1 mg/kg, subcutaneously 5 days/week) for 10 weeks. In groups 1 and 3-5, the right hindlimb was immobilized. At the end of treatment, the femurs were removed and tested for bone porosity, bone mechanical properties, and cortical microarchitecture. Treatment with propranolol induced greater reductions in the bone porosity of the right femur and improved the mechanical properties of the femoral mid-shaft femur in comparison to the IMM control. Moreover, treatment with propranolol also improved the microarchitecture of cortical bones when compared with the IMM control, as indicated by scanning electron microscopy. The anti-osteoporotic property of propranolol was comparable with zoledronic acid and alfacalcidol. This study shows that the bone resorption induced by immobilization/disuse in rats can be suppressed by treatment with propranolol.