Early effects of ovariectomy on bone microstructure, bone turnover markers and mechanical properties in rats

Limosilactobacillus reuteri with menaquinone-7 improves bone biomechanics and microarchitecture in ovariectomized mice: preliminary study

AIM

This study aimed to evaluate the effects of Limosilactobacillus reuteri (LR) and its combination with menaquinone-7 (MK-7; K) on ovariectomy-induced bone loss in mice and on bacterial growth in vitro.

METHODS

In the in vivo study, animals were divided into five groups: sham-operated (SHAM); ovariectomy (OVX); OVX-LR; OVX-K; OVX-LR-K. After 4 weeks of treatment, femur cortical biomechanical properties, vertebral microarchitecture, osteocalcin levels, Occludin and Jam3 expression, and intestinal histomorphometry were evaluated. In vitro, microbial growth was assessed by incubating L. reuteri with MK-7. After incubation, optical densities were measured, and bacteria were cultured on MRS agar for the colony-forming unit (CFU/ml) counting.

RESULTS

L. reuteri, MK-7, and their combination significantly improved femur intrinsic biomechanical properties and cortical vertebral thickness. The combined treatment exhibited a synergistic effect on the modulus of elasticity, and increased cortical vertebral volume and the villus/crypt ratio in comparison to OVX. L. reuteri and its combination with MK-7 restored vertebral trabecular microarchitecture values to SHAM levels. However, no significant differences were observed in serum levels of osteocalcin, Occludin or Jam3 expression among groups. In vitro, a significant increase in optical density and viable cell count was observed after 4 h of incubation.

CONCLUSION

L. reuteri and its combination with MK-7 improved bone biomechanical and microarchitecture properties. We propose a synergistic preventive action of L. reuteri and MK-7 in estrogen-deficient mice. Additionally, the enhanced survival of L. reuteri in the presence of MK-7 may partially explain the observed benefits of the combined treatment in vivo.

The protective effects of tectoridin on bone fractures against oxidative stress via the inhibition of NF-κB and apoptotic pathways in ovariectomized rats

Oxidative stress and inflammation lead to high bone turnover, contributing to osteoporosis caused by estrogen deficiency in postmenopausal women. Tectoridin, an isoflavonoid with antioxidant and anti-inflammatory properties, was evaluated for its protective effects in ovariectomized (OVX) rats, a model of postmenopausal osteoporosis. Five groups of female rats (n = 6) were established: normal, OVX control, OVX treated with tectoridin at 10 and 20 mg/kg bw, and OVX treated with estrogen, over a four-week period. Tectoridin treatment resulted in reduced body weight and improved femur weight and thickness. Serum E2, calcium, and phosphate levels increased, while alkaline phosphatase (ALP) levels decreased after treatment. Additionally, tectoridin altered lipid profiles by decreasing total cholesterol (TC), triglycerides (TG), and low-density lipoprotein (LDL), while increasing high-density lipoprotein (HDL). The treatment elevated serum bone-specific alkaline phosphatase (BALP) and procollagen type I N-terminal propeptide (PINP) levels, and decreased levels of bone resorption markers CTX-1 and NTx. Tectoridin upregulated osteogenic markers Runx2, Osx, and BMP2, suggesting enhanced bone properties. Moreover, it reduced lipid peroxidation and increased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities, indicating reduced oxidative stress. Tectoridin also inhibited inflammatory proteins and exhibited anti-apoptotic effects on Bax/Caspase3 and Bcl2 expression. This study highlights the potential of tectoridin in modulating oxidative stress, inflammation, and improving bone remodeling in OVX rats, making it a candidate for managing postmenopausal osteoporosis.

A cross-sectional study on the correlation between fasting blood glucose and bone turnover markers in Chinese patients with osteoporotic fractures

Background

Recent studies suggest that metabolic factors, such as fasting blood glucose (FBG), may significantly affect bone health, influencing the risk and severity of osteoporotic fractures (OPFs). This study examined the association between FBG levels and bone turnover markers (BTMs) in patients hospitalized for OPFs requiring surgical intervention.

Methods

A retrospective cross-sectional analysis was conducted on 888 patients treated for OPFs at Kunshan Hospital affiliated with Jiangsu University from November 2018 to August 2023. Serum levels of FBG, procollagen type 1 N-terminal propeptide (P1NP), and β-C-terminal telopeptide of type I collagen (β-CTX) were measured, with FBG serving as an independent variable, and P1NP and β-CTX as outcome variables. Patients were stratified into tertiles based on FBG levels, and multiple regression models were adjusted for confounding variables, including age, gender, BMI, and clinical parameters. Non-linear relationships and threshold effects were analyzed.

Results

Adjusted regression models identified a negative association between FBG and BTMs. For each 1 mmol/L increase in FBG, β-CTX levels decreased by 0.02 ng/mL (95% CI: -0.04 to -0.01; p < 0.01), and P1NP levels decreased by 2.91 ng/mL (95% CI: -4.38 to -1.45; p < 0.01). Non-linear relationships were observed, with an inflection point at 7.93 mmol/L for both markers. Below this threshold, higher FBG levels were associated with a steeper decline in BTMs.

Conclusion

FBG levels exhibit a negative non-linear association with P1NP and β-CTX in patients with OPFs. Elevated FBG levels may adversely affect BTMs, potentially contributing to the progression of osteoporosis (OP). These findings underscore the importance of glycemic control in managing bone health among patients with OPFs.

Impact of different 3D regions of interest on quantifying dynamic lumbar vertebral microstructure in ovariectomized rats-a micro-CT study

Introduction

The selection of regions of interest (ROIs) is crucial for accurate microcomputed tomography (micro-CT) analysis. Distinct ROI selection methods exist for lumbar vertebras in osteoporotic animal model research. However, whether different ROIs directly affect the results of quantitative micro-CT-based microarchitectural data is still unknown. This study aimed to compare the diagnostic accuracy of two commonly used ROIs of lumbar vertebras in ovariectomized (OVX) rats at different time points.

Methods

Rats were randomly divided into the baseline group, the sham/OVX-operated groups, with 12- or 24-weeks sham (Sham 12w or Sham 24w)/12- or 24-weeks (OVX 12w or OVX 24w)-operated group (n = 6 in every group). The fifth lumbar vertebras were collected and scanned using micro-CT. Quantitative analyses of bone microarchitecture parameters were conducted separately for the central ROI (ROI 1) and overall ROI (ROI 2).

Results

The results indicated that the Tb.N of baseline group rats for ROI 1 was significantly lower than that for ROI 2. The Tb.Th of rats of the Sham 12w and Sham 24w groups was significantly increased compared to that of the baseline group rats using the ROI 2 analysis. The bone mineral density (BMD) and bone volume fraction (BV/TV) were significantly lower by the ROI 1 than by the ROI 2 in all groups. The BMD and BV/TV also showed a significant reduction at 24 weeks postoperatively compared with those at 12 weeks postoperatively. Bland-Altman analysis showed good consistency between the two different ROI selection methods.

Conclusion

This study found that capturing peripheral trabeculas (overall ROI) does not explain the increased Tb.Th in healthy mice and decreased Tb.N in OVX mice; both findings indicate that this is evident in both ROI. Moreover, this study suggested the potential value of the central ROI (effective and quicker) for evaluating osteoporosis of the lumbar vertebras in OVX rats and provides a basis for analyzing the morphological changes of lumbar trabecular.

Combination of ferulic acid and exercise alleviates menopause symptoms and skin remodeling in ovariectomized rats

BACKGROUND/OBJECTIVES

Estrogen regulates certain biological functions, including bone health, maintenance of skin components, and cardiovascular and brain protection. Estrogen deficiency manifests as hot flashes, wrinkles, skin dryness, reduced bone mineral density (BMD), sleep disorders, and cardiovascular diseases. This study aimed to investigate the effects of aerobic exercise combined with ferulic acid (FA) in ovariectomized rats.

MATERIALS/METHODS

Female Sprague-Dawley rats were classified into control (N), ovariectomy (OV), ovariectomy and exercise (OV+EX), and ovariectomy and exercise with ferulic acid (OV+EX+F) groups. Following ovariectomy at 22 weeks of age, the rats were tower climbing exercise at gradually increase the load (3 days/week for 12 weeks) with or without FA (5 g/kg diet) administration.

RESULTS

Estrogen deficiency in female rats (OV group) resulted in increased body weight, increased blood triglyceride (TG) levels, and decreased BMD following ovariectomy. Interestingly, compared with the rats in the OV group, the rats in the OV+EX+F group exhibited reduced body weight and blood TG levels and maintained BMD following ovariectomy, similar to those in the N group. Histological analysis of the skin of estrogen-deficient rats (OV group) revealed significantly decreased skin thickness with fewer dermal cells and distorted subcutaneous fat layers, similar to the aging phenotype. Interestingly, the rats in the OV+EX+F group exhibited rescued skin phenotypes compared with those in the OV and OV+EX groups. The skin of rats from all groups was analyzed for the expression of DNA damage and repair proteins. The OV+EX+F and OV+EX groups exhibited enhanced protein levels of pCHK1 (S345), an initiator of DNA repair signaling, and p53, indicating increased cellular DNA damage because of ovariectomy and ultimately an underlying DNA repair process.

CONCLUSION

Exercise with FA had beneficial effects on lipid profiles, BMD, and skin remodeling during menopause.

Puerarin alleviates osteoporosis in rats by targeting the JAK2/STAT3 signaling pathway

Osteoporosis (OP) is a common chronic progressive bone disease that increases fracture risk in postmenopausal women. Research suggests that puerarin (Pue) may be an effective treatment for OP. This study examined the effects and underlying mechanisms of Pue in treating postmenopausal osteoporosis (PMOP) in rats. Sprague-Dawley (SD) rats underwent bilateral ovariectomy to simulate PMOP and were then treated with subcutaneous injections of Pue. Bone mineral density (BMD) was measured using a bone densitometer. Micro-CT scans assessed femur bone structure and various parameters were calculated: bone volume fraction (BV/TV), bone surface density (BS/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), and bone surface area-to-bone volume ratio (BS/BV). Hematoxylin-eosin (HE) staining was employed to observe femoral tissue pathology. Serum levels of bone formation metabolism-related markers-osteocalcin (OC), bone alkaline phosphatase (BALP), and procollagen type I N-terminal propeptide (PINP)-were measured via enzyme-linked immunosorbent assay (ELISA). The protein expression levels of the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway in bone tissue were evaluated using Western blotting assay. The results showed improved bone density and reduced bone loss in rats treated with Pue. There were also significant increases in serum levels of OC and BALP, indicating enhanced osteogenesis. Furthermore, there was a decrease in activation of the JAK2/STAT3 pathway in femoral tissue, suggesting a pathway inhibition. These findings indicate that Pue may combat osteoporosis by promoting osteogenesis and inhibiting activation of the JAK2/STAT3 pathway activation.

The effects of simvastatin on the bone microstructure and mechanics of ovariectomized mice: a micro-CT and micro-finite element analysis study

BACKGROUND

Osteoporosis is a major health concern for postmenopausal women, and the effect of simvastatin (Sim) on bone metabolism is controversial. This study aimed to investigate the effect of simvastatin on the bone microstructure and bone mechanical properties in ovariectomized (OVX) mice.

METHODS

24 female C57BL/6J mice (8-week-old) were randomly allocated into three groups including the OVX + Sim group, the OVX group and the control group. At 8 weeks after operation, the L4 vertebral bones were dissected completely for micro-Computed Tomography (micro-CT) scanning and micro-finite element analysis (µFEA). The differences between three groups were compared using ANOVA with a LSD correction, and the relationship between bone microstructure and mechanical properties was analyzed using linear regression.

RESULTS

Bone volume fraction, trabecular number, connectivity density and trabecular tissue mineral density in the OVX + Sim group were significantly higher than those in the OVX group (P < 0.05). For the mechanical properties detected via µFEA, the OVX + Sim group had lower total deformation, equivalent elastic strain and equivalent stress compared to the OVX group (P < 0.05). In the three groups, the mechanical parameters were significantly correlated with bone volume fraction and trabecular bone mineral density.

CONCLUSIONS

The findings suggested that simvastatin had a potential role in the treatment of osteoporosis. The results of this study could guide future research on simvastatin and support the development of simvastatin-based treatments to improve bone health.

Murine Orchiectomy and Ovariectomy to Reduce Sex Hormone Production

Sex hormone signaling plays a critical role in multiple organ systems as well as in the progression of various diseases, including neurodegenerative disease. The manipulation of sex hormone levels in the murine model system allows for the study of their impact on organs/tissues and within disease progression. Orchiectomy - the surgical removal of the testes - and ovariectomy - the surgical removal of the ovaries - provide a method to deplete the endogenous sex hormones so that the precise hormone levels can be provided through drug or other delivery methods. Here, we provide rapid and minimally invasive methods for both orchiectomy and ovariectomy in the murine model system for the reduction of sex hormones. This protocol details the surgical preparation and excision of the testes through the scrotal sac, and excision of the ovaries via two incisions in the right and left lateral dorsum.

Periodontal ligament and alveolar bone remodeling during long orthodontic tooth movement analyzed by a novel user-independent 3D-methodology

The structural process of bone and periodontal ligament (PDL) remodeling during long-term orthodontic tooth movement (OTM) has not been satisfactorily described yet. Although the mechanism of bone changes in the directly affected alveolar bone has been deeply investigated, detailed knowledge about specific mechanism of PDL remodeling and its interaction with alveolar bone during OTM is missing. This work aims to provide an accurate and user-independent analysis of the alveolar bone and PDL remodeling following a prolonged OTM treatment in mice. Orthodontic forces were applied using a Ni-Ti coil-spring in a split-mouth mice model. After 5 weeks both sides of maxillae were scanned by high-resolution micro-CT. Following a precise tooth movement estimation, an extensive 3D analysis of the alveolar bone adjacent to the first molar were performed to estimate the morphological and compositional parameters. Additionally, changes of PDL were characterized by using a novel 3D model approach. Bone loss and thinning, higher connectivity as well as lower bone mineral density were found in both studied regions. Also, a non-uniformly widened PDL with increased thickness was observed. The extended and novel methodology in this study provides a comprehensive insight about the alveolar bone and PDL remodeling process after a long-duration OTM.

The Effect of Omega-9 on Bone Viscoelasticity and Strength in an Ovariectomized Diet-Fed Murine Model

Few studies have investigated the effect of a monosaturated diet high in ω-9 on osteoporosis. We hypothesized that omega-9 (ω-9) protects ovariectomized (OVX) mice from a decline in bone microarchitecture, tissue loss, and mechanical strength, thereby serving as a modifiable dietary intervention against osteoporotic deterioration. Female C57BL/6J mice were assigned to sham-ovariectomy, ovariectomy, or ovariectomy + estradiol treatment prior to switching their feed to a diet high in ω-9 for 12 weeks. Tibiae were evaluated using DMA, 3-point-bending, histomorphometry, and microCT. A significant decrease in lean mass (p = 0.05), tibial area (p = 0.009), and cross-sectional moment of inertia (p = 0.028) was measured in OVX mice compared to the control. A trend was seen where OVX bone displayed increased elastic modulus, ductility, storage modulus, and loss modulus, suggesting the ω-9 diet paradoxically increased both stiffness and viscosity. This implies beneficial alterations on the macro-structural, and micro-tissue level in OVX bone, potentially decreasing the fracture risk. Supporting this, no significant differences in ultimate, fracture, and yield stresses were measured. A diet high in ω-9 did not prevent microarchitectural deterioration, nevertheless, healthy tibial strength and resistance to fracture was maintained via mechanisms independent of bone structure/shape. Further investigation of ω-9 as a therapeutic in osteoporosis is warranted.