Daily parathyroid hormone administration enhances bone turnover and preserves bone structure after severe immobilization-induced bone loss

Physiol Rep, 2017 · DOI: 10.14814/phy2.13446 · Published: September 1, 2017

Spinal Cord Injury Endocrinology Orthopedics

Simple Explanation

This study investigates the effect of parathyroid hormone (PTH) on bone loss caused by immobilization following spinal cord injury (SCI) in mice. Mice with SCI were given daily PTH injections, and their bone structure and turnover were compared to SCI mice without PTH and to healthy control mice. The results showed that SCI led to significant bone loss and reduced bone turnover. However, PTH treatment helped restore bone volume and connectivity, reduced bone loss in the outer layer (cortical bone), and maintained the number of bone-building and bone-resorbing cells. These findings suggest that PTH could be a useful treatment for preventing bone loss in people with SCI who experience severe immobilization.

Study Duration

35 days

Participants

24-week-old, female C57BL/6 mice

Evidence Level

Level 1, Animal Study

Key Findings

1
SCI-vehicle animals exhibited a marked decrease in proximal tibial fractional trabecular bone volume and trabecular thickness compared to the control sham-vehicle group.
2
PTH treatment protected against SCI-induced trabecular bone loss and preserved bone architecture.
3
PTH injection preserved cortical thickness and volume and abolished the increase in porosity observed in femurs of SCI animals.

Research Summary

This study demonstrates that severe immobilization following SCI leads to significant bone loss and reduced bone turnover in mice. Daily administration of PTH protects against SCI-induced bone loss by promoting bone formation and resorption, thereby maintaining bone microarchitecture. The findings suggest that intermittent PTHR1 activation could be a beneficial therapeutic strategy for preserving bone integrity after severe immobilization.

Practical Implications

Potential Therapeutic Strategy

Intermittent PTH administration may be an effective anabolic approach for treating bone loss in patients with severe disuse osteoporosis, such as those with SCI.

Improved Bone Integrity

PTH treatment can restore bone integrity by enhancing bone formation and improving bone microarchitecture, potentially reducing the risk of fractures.

Clinical Trials Justification

The study supports the need for clinical trials to evaluate the efficacy of PTH in reducing bone loss and improving bone health in individuals with SCI.

Study Limitations

1
The course of PTH treatment started immediately after SCI; further investigations are required to address the efficacy of PTH after chronic SCI.
2
While we anticipate that PTH will be efficacious in male animals, this should be independently verified.
3
The study was conducted on mice and may not directly translate to human outcomes.

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