Zebrafish models for glucocorticoid-induced osteoporosis

A review of osteoporotic vertebral fracture animal models

INTRODUCTION

Osteoporotic vertebral fractures are a common outcome of osteoporosis, imposing a substantial economic burden. The development of reliable animal models is essential for advancing research. This review examines osteoporotic vertebral fracture models across various animal species.

METHODS

The review compares and analyzes the different approaches used to model osteoporotic vertebral fractures in experimental animals, synthesizing the existing design protocols.

RESULTS

Rats and sheep are the primary experimental animals utilized in vertebral fracture research. The predominant approach in model design remains the creation of bone defects to simulate vertebral fractures. The spontaneous fracture model is primarily applicable to small species, such as transgenic mice. Rabbits and zebrafish are not suitable for modeling vertebral fractures due to the low cancellous bone content in their lumbar. The bone loss in the lumbar cancellous bone of the dog osteoporosis model is minimal, making it unsuitable for fracture modeling.

CONCLUSIONS

The bone defect model remains the most widely used approach for osteoporotic vertebral fractures. However, the stress compression model shows promise as a potential focal point for future investigations.

Lipid peroxidation inhibition by icaritin and its glycosides as a strategy to combat iron overload-induced osteoporosis in zebrafish

This study provides a comprehensive evaluation of the anti-osteoporotic effects of flavonoids derived from Epimedium, including icaritin and its six glycosides-icariside I, icariside II, icariin, epimedin A, epimedin B, and epimedin C-using a zebrafish model of iron overload-induced osteoporosis. Our results demonstrate a significant increase in lipid peroxidation in zebrafish subjected to ferric ammonium citrate (FAC)-induced osteoporosis, along with impaired expression and activity of glutathione peroxidase 4 (GPX4). Treatment with ferrostatin-1, a lipid peroxide scavenger, partially alleviated the osteoporotic effects induced by FAC, implying that lipid peroxidation may play a key role in iron overload-related osteoporosis. We observed varying degrees of anti-osteoporotic activity and enhancement of osteogenic differentiation markers, such as bmp2b, runx2b, col1a1a, and alp, among icaritin and its glycosides. Notably, icaritin exhibited the most potent inhibitory effects on osteoporosis, while epimedin A and epimedin B showed enhanced efficacy compared to other glycosides, correlating closely with their ability to suppress lipid peroxidation. Additionally, through CETSA, molecular docking, and dynamic simulation studies, we identified an interaction between icaritin and GPX4, which may help stabilizing GPX4 against FAC-induced lipid peroxidation. These findings suggest that the anti-osteoporotic effects of icaritin and its glycosides are linked to their ability to suppress lipid peroxidation, offering potential therapeutic insights for managing iron overload-induced osteoporosis.

Bone quality in zebrafish vertebrae improves after alendronate administration in a glucocorticoid-induced osteoporosis model

Glucocorticoid-induced osteoporosis (GIOP) changes the microarchitecture of bones and often leads to the reduction of bone-mineral density (BMD) and increased fracture rates. Zebrafish has been used as an alternative model for GIOP, however, the interaction of GIOP, and its treatment, with zebrafish bone morphometrics and mechanical properties, remains a challenge. Thus, this study aimed to evaluate the effects of prednisolone and alendronate on the properties of zebrafish vertebrae. Adult 7-month-old zebrafish were distributed into four groups: control (CTRL), prednisolone-only (PN), alendronate-only (ALN), and the sequential use of both medicines (PN + ALN). Fish skeletons were scanned via micro-tomography (n = 3) to obtain vertebra morphometrics (e.g., BMD). Bone morphology was assessed using scanning electron microscopy (n = 4) and the biomechanical behaviour with nanoindentation technique (n = 3). The BMD decreased in PN (426.08 ± 18.58 mg/cm3) and ALN (398.23 ± 10.20 mg/cm3) groups compared to the CTRL (490.43 ± 41.96 mg/cm3) (p < 0.001); however, administering the medicines in sequence recovered the values to healthy levels (495.43 ± 22.06 mg/cm3) (p > 0.05). The bone layered structures remain preserved in all groups. The vertebrae of the groups that received ALN and PN + ALN, displayed higher modulus of elasticity (27.27 ± 1.59 GPa and 25.68 ± 2.07 GPa, respectively) than the CTRL (22.74 ± 1.60 GP) (p < 0.001). ALN alone increased the hardness of zebrafish vertebrae to the highest value among the treatments (1.32 ± 0.13 GPa) (p < 0.001). Conversely, PN + ALN (1.25 ± 0.11 GPa) showed unaltered hardness from the CTRL (1.18 ± 0.13 GPa), but significantly higher than the PN group (1.08 ± 0.12 GPa) (p < 0.001). ALN administered after GIOP development, rescued osteoporotic condition by recovering the BMD and bone hardness in zebrafish vertebrae.

Potential therapeutic role of spermine via Rac1 in osteoporosis: Insights from zebrafish and mice

Osteoporosis is a prevalent metabolic bone disease. While drug therapy is essential to prevent bone loss in osteoporotic patients, current treatments are limited by side effects and high costs, necessitating the development of more effective and safer targeted therapies. Utilizing a zebrafish ( Danio rerio) larval model of osteoporosis, we explored the influence of the metabolite spermine on bone homeostasis. Results showed that spermine exhibited dual activity in osteoporotic zebrafish larvae by increasing bone formation and decreasing bone resorption. Spermine not only demonstrated excellent biosafety but also mitigated prednisolone-induced embryonic neurotoxicity and cardiotoxicity. Notably, spermine showcased protective attributes in the nervous systems of both zebrafish embryos and larvae. At the molecular level, Rac1 was identified as playing a pivotal role in mediating the anti-osteoporotic effects of spermine, with P53 potentially acting downstream of Rac1. These findings were confirmed using mouse ( Mus musculus) models, in which spermine not only ameliorated osteoporosis but also promoted bone formation and mineralization under healthy conditions, suggesting strong potential as a bone-strengthening agent. This study underscores the beneficial role of spermine in osteoporotic bone homeostasis and skeletal system development, highlighting pivotal molecular mediators. Given their efficacy and safety, human endogenous metabolites like spermine are promising candidates for new anti-osteoporotic drug development and daily bone-fortifying agents.