01-12-2015 | Original Article
Calcitonin suppresses intervertebral disk degeneration and preserves lumbar vertebral bone mineral density and bone strength in ovariectomized rats
Published in: Osteoporosis International | Issue 12/2015
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Summary
We investigated the effect of calcitonin (CT) on lumbar intervertebral disk degeneration (LIDD) in rats with ovariectomy-induced osteopenia. CT protected ovariectomized rats from LIDD by, at least in part, modifying extracellular matrix metabolism of the disks and preserving the microarchitecture and biomechanical properties of adjacent vertebrae.
Introduction
The present study aimed to investigate the effect of CT on lumbar vertebral bone mineral density and intervertebral disk degeneration in ovariectomized (OVX) rats.
Methods
We first subjected 50 3-month-old female rats to either OVX (n = 30) or sham (n = 20). Twelve weeks later, ten OVX and ten sham rats were necropsied. The remaining OVX rats began to receive either saline vehicle (OVX + V, n = 10), or salmon CT (OVX + CT, 16 IU/kg/2 days, n = 10). After 12 weeks of treatment, necropsy was conducted and bone mineral density was determined in L3–4 and L5–6 vertebrae. The microstructure and biomechanical properties of L3 vertebrae were detected by micro-computed tomography and compression test, respectively. L5–6 was also used to measure intervertebral disk height and observe intervertebral disk histological changes by Van Gieson staining and histological scores, as well as immunohistochemistry (IHC) analysis of matrix metalloprotease (MMP)-1, MMP-13, and collagen II expression.
Results
At 12 weeks post-OVX, OVX rats had lower BV/TV and Tb.N and higher intervertebral disk histological score than sham rats. After 24 weeks, OVX + CT rats had higher BMD, BV/TV, Tb.N, and bone biomechanical strength values than OVX + V rats. Histological analysis showed OVX + CT rats had significantly lower disk degeneration scores than OVX + V rats. IHC analysis revealed CT treatment decreased expression of MMP-1 and MMP-13 and increased expression of collagen II compared with OVX + V rats.
Conclusions
Our data demonstrate that CT-treated OVX rats display less intervertebral disk degeneration and favorable changes in intervertebral disk metabolism, associated with higher trabecular bone mass, better trabecular microarchitecture, and better biomechanical strength when compared to vehicle-treated OVX rats.