Effect of Sequential Treatment with Bisphosphonates After Teriparatide in Ovariectomized Rats: A Direct Comparison Between Risedronate and Alendronate

Alamandine attenuates ovariectomy-induced osteoporosis by promoting osteogenic differentiation via AMPK/eNOS axis

BACKGROUND

Alamandine is a newly characterized peptide of renin angiotensin system. Our study aims to investigate the osteo-preservative effects of alamandine, explore underlying mechanism and bring a potential preventive strategy for postmenopausal osteoporosis in the future.

METHODS

An ovariectomy (OVX)-induced rat osteoporosis model was established for in vivo experiments. Micro-computed tomography and three-point bending test were used to evaluate bone strength. Histological femur slices were processed for immunohistochemistry (IHC). Bone turnover markers and nitric oxide (NO) concentrations in serum were determined with enzyme-linked immunosorbent assay (ELISA). The mouse embryo osteoblast precursor (MC3T3-E1) cells were used for in vitro experiments. The cell viability was analysed with a Cell Counting Kit‑8. We performed Alizarin Red S staining and alkaline phosphatase (ALP) activity assay to observe the differentiation status of osteoblasts. Western blotting was adopted to detect the expression of osteogenesis related proteins and AMP-activated protein kinase/endothelial nitric oxide synthase (AMPK/eNOS) in osteoblasts. DAF-FM diacetate was used for semi-quantitation of intracellular NO.

RESULTS

In OVX rats, alamandine alleviated osteoporosis and maintained bone strength. The IHC showed alamandine increased osteocalcin and collagen type I α1 (COL1A1) expression. The ELISA revealed alamandine decreased bone turnover markers and restored NO level in serum. In MC3T3-E1 cells, alamandine promoted osteogenic differentiation. Western blotting demonstrated that alamandine upregulated the expression of osteopontin, Runt-related transcription factor 2 and COL1A1. The intracellular NO was also raised by alamandine. Additionally, the activation of AMPK/eNOS axis mediated the effects of alamandine on MC3T3-E1 cells and bone tissue. PD123319 and dorsomorphin could repress the regulating effect of alamandine on bone metabolism.

CONCLUSION

Alamandine attenuates ovariectomy-induced osteoporosis by promoting osteogenic differentiation via AMPK/eNOS axis.

Effects of risedronate, alendronate, and minodronate alone or in combination with eldecalcitol on bone mineral density, quality, and strength in ovariectomized rats

Combination therapy of active vitamin D₃ with some bisphosphonates (BPs) has been reported to be clinically beneficial. However, combination therapy of eldecalcitol (ELD) with BP has to date not been validated as to whether it is beneficial in the clinical setting. Preclinical studies suggested that simultaneous treatment with ELD and some BPs is more effective than monotherapy. However, the relative potency of various BPs, when used in combination with ELD, is completely unknown. In this study, we examined and compared the effects of risedronate (RIS), alendronate (ALN), and minodronate (MIN) alone or in combination with ELD on bone mass, microarchitecture, strength, and material properties in ovariectomized Sprague-Dawley rats aged 13 weeks. RIS, ALN, MIN, and ELD were administered five times weekly for 16 weeks. Micro-computed tomography analysis, compression test, and Fourier transform infrared (FTIR) imaging analysis were performed 16 weeks after treatment initiation. Trabecular and cortical bone mineral density (BMD) in the fourth lumbar vertebra (L4) significantly increased in the RIS + ELD, ALN + ELD, and MIN + ELD groups compared with the vehicle group. Moreover, the bone microarchitecture of L4 in all the BP + ELD groups also significantly improved. On mechanical testing of L4, the maximum load was significantly increased in the RIS + ELD and ALN + ELD groups. FTIR analysis revealed that the mineral-to-collagen ratio of trabecular bone in L3 of all the BP + ELD groups was significantly increased compared with the vehicle group. By contrast, the carbonate-to-phosphate ratio, a parameter of mineral immaturity, was significantly decreased in the RIS + ELD and ALN + ELD groups. BP + ELD improved the BMD and structural properties of the bone to a similar extent. RIS + ELD and ALN + ELD also improved bone strength. Furthermore, treatment with BP + ELD improved the bone material. These results suggest that the combination therapy of BP and ELD is beneficial and warrants further clinical trials.

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Combination of bisphosphonates and eldecalcitol was superior to either monotherapy.

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Bone quality on FTIR imaging analysis correlated with bone strength.

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Combined bisphosphonate and eldecalcitol may be useful in the clinical setting.

Prevention of ovariectomy-induced osteoporosis in rats : Comparative study of zoledronic acid, parathyroid hormone (1-34) and strontium ranelate

Recently, the use of the pharmacological agents strontium ranelate (SR), parathyroid hormone (1-34, PTH) and zoledronic acid (ZA) has come to prominence for the treatment of osteoporosis due to their ability to prevent bone loss in osteoporotic patients. Although much emphasis has been placed on using pharmacological agents for the prevention of disease, much less attention has been placed on which one is more effective. There is still no direct comparative study on these three drugs. The aim of the present study was to investigate the effect of SR, PTH, ZA on preventing ovariectomy-induced osteoporosis in rats. After bilateral ovariectomy the rats randomly received vehicle, SR (500 mg/kg body weight/day, orally), PTH (20 μg/kg/day, subcutaneously) or a single injection of ZA (0.1 mg/kg, i.v.) until death at 12 weeks. The distal femurs were harvested for evaluation of bone metabolism. The rats treated with ZA demonstrated the highest levels of new bone formation as assessed by microcomputed tomography (CT), biomechanical strength, histological analysis and bone metabolism. Furthermore, PTH and SR showed a stronger effect on improving trabecular bone mass at 12 weeks. The results from the present study demonstrate that systemic administration of PTH, SR and ZA could prevent bone loss, while a single dose of ZA has a better effect on preventing ovariectomy-induced osteoporosis than either PTH or SR.