Abstract:

BACKGROUND: Osteoprotegerin gene knock-out (OPG-/-) mice have been shown to demonstrate significant osteoporosis and osteoarthritis phenotype.
OBJECTIVE: To observe the relationship between lumbar intervertebral disc degeneration and vertebral osteoporosis in OPG-/- mice with aging.
METHODS: The third lumbar vertebrae (L3) and the L4/5 lumbar intervertebral discs (L4/5) from 4-, 8-, 12-week-old mice were harvested. Bone micro-architecture of the L3 was evaluated using Micro-CT; L4/5 was stained using hematoxylin and eosin for routine morphologic examination to measure the height of intervertebral disc and cartilage endplate.
RESULTS AND CONCLUSION: Compared with the control group, the third lumbar vertebras in OPG-/- mice appeared with significantly drop in bone mass: trabecular number, trabecular thickness and bone volume fraction significantly declined compared with normal mice of the same age, with a statistical difference between them (P < 0.05); while trabecular separation/spacing, structure model index increased compared with control group, and there ws a statistical difference between them (P < 0.05). Hematoxylin-eosin staining exhibited degeneration of the intervertebral disc and cartilage endplate in OPG-/- mice: irregular arrangement of cartilage endplate was observed, and bone marrow cavity tissue was observed in the endplate cartilage and annulus fibrosis. OPG gene plays a very important role in maintaining the structure and function of the normal intervertebral disc, the deletion of OPG gene causes intervertebral disc degeneration and vertebra osteoporosis.