Skeletal deterioration induced by RANKL infusion: a model for high-turnover bone disease.

Area of Science:

• Skeletal Biology
• Bone Physiology
• Osteoporosis Research

Background:

• Receptor Activator of Nuclear Factor kappa-B Ligand (RANKL) is crucial for osteoclast development.
• The direct skeletal effects of excess RANKL on bone turnover, mineralization, and architecture remain incompletely understood.
• A novel bone loss model was developed by continuously administering soluble RANKL to mature rats.

Purpose of the Study:

• To investigate the skeletal consequences of continuous RANKL administration in rats.
• To evaluate the impact of RANKL on bone turnover, material, structural, and mechanical properties.
• To establish a potential disease model for high bone turnover conditions.

Main Methods:

• Mature Sprague-Dawley rats received continuous administration of saline (control) or human RANKL (35 or 175 microg/kg/day) for 28 days.
• Serum markers of bone turnover were monitored throughout the study.
• Analysis included bone mineral density, microarchitecture, material properties, mechanical testing of femurs, and aortic mineral content.

Main Results:

• High-dose RANKL significantly increased serum osteocalcin and TRAP-5b, indicating heightened bone turnover.
• RANKL administration reduced femur cortical bone volume and proximal tibia trabecular bone volume fraction.
• Bone quality was compromised, with decreased mineralization, impaired trabecular connectivity, and increased endocortical resorption, leading to reduced mechanical properties.

Conclusions:

• Continuous RANKL infusion induces widespread detrimental skeletal effects in rats.
• The observed skeletal changes closely resemble those seen in high-turnover bone diseases, including postmenopausal osteoporosis.
• This RANKL-induced bone loss model offers a valuable tool for studying osteoporosis and related skeletal disorders.