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Study Design: Neovascularization and expression of inflammatory cytokines were examined in Osteoprotegerin (Opg) knockout (KO) mice that show intervertebral disc (IVD) degeneration.Objective: The aim of this study was to clarify the pathological changes in lumbar IVD degeneration in Opg KO mice.Summary Of Background Data: Osteoporosis is a controversial risk factor for IVD degeneration. Deletion of Opg resulted in IVD degeneration in mice. Neovascularization and inflammatory cytokines are key factors in IVD degeneration.Methods: Opg KO mice and their wild-type (WT) littermates were euthanized. Lumbar IVDs were harvested. Safranin O/Fast Green staining was performed to examine the pathological changes. Microcomputed tomographic (micro-CT) analysis was performed to determine the structural changes at the junction of lumbar IVD cartilage and vertebrae. Tartrate-resistant acid phosphatase (TRAP) staining was performed to evaluate osteoclast formation. Protein expression of vascular endothelial growth factor A (VEGF-A), CD31, VE-cadherin, CD 34, interleukin-1β (IL-1β), and tumor necrosis factors α (TNF-α) were analyzed by immunohistochemistry (IHC) assays. Gene expressions of IL-1β, IL-6, and TNF-α were analyzed by real-time polymerase chain reaction (RT-PCR).Results: In 12-week-old Opg KO mice, new bone was formed in the endplate cartilage of lumbar IVDs and this became more obvious in 24-week-old Opg KO mice. Three-dimensional (3D) μCT reconstruction analyses showed that the edges of the L4 and L5 vertebrae were rugged with bone marrow cavities in it. Protein expression of VEGF-A, CD31, VE-cadherin, and CD34 was increased in the endplate and growth plate of lumbar IVDs of Opg KO mice. Gene expression of IL-1β, IL-6, and TNF-α as well as protein expression of IL-1β and TNF-α were highly expressed in the lumbar IVDs of Opg KO mice.Conclusion: Deletion of Opg leads to increased neovascularization and expression of inflammatory cytokines in the lumbar disc in Opg KO mice, which may play important roles in IVD degeneration.Level Of Evidence: N/A. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the impact of prolonged and repeated upright posture on the cartilage end plate of the lumbar vertebrae of rats. The study utilized 30 rats which were amputated to stand upright on their hind-limbs and were killed at 5, 7, and 9 months after the surgery to harvest their lumbar vertebrae samples for analysis. The study found that prolonged upright posture causes cartilage end plate calcification and hypertrophy in the lumbar spine of the rats.

Study Design: An in vivo study of the cervical intervertebral discs (IVDs) response to upright posture was performed using an amputated bipedal rat model. Objective: To investigate the effects of upright posture on IVDs of rat cervical spine. Summary Of Background Data: The distinct arrangement of human neck muscle from that of cat and rhesus indicated that in the evolution process, upright posture might have affected cervical spine of human ancestors. However, the effects of upright posture on cervical spine have not been assessed. Methods: Forty-one-month-old rats were randomly divided into 5-month-control, 5-month-surgery, 7-month-control, and 7-month surgery group (n = 10 per group). Both forelimbs of 2 surgery group rats were amputated, and those rats were then induced to be upright in the custom-made cages. Two control group rats were kept in regular cages. These rats were respectively killed at the fifth and seventh month after surgery and the IVD samples of lumbar spine were harvested for histologic and immunohistochemical studies. Total RNA isolated from these samples were used for real-time polymerase chain reaction of type II collagen (Col2a1), type X collagen, matrix metalloproteinase 13 (MMP-13), MMP-3, aggre-can, and aggrecanase-2 (ADAMTS-5). Results: Upright posture affects histologic changes of the cervical IVDs such as fissures of anulus fibrosus and decreased height of disc, decreased protein level of Col2a1 at nucleus pulposus and anulus fibrosus, up-regulated MMP-13, MMP-3, ADAMTS-5, and type X collagen mRNA expression, and downregulated mRNA expression of Col2a1 and aggrecan. Conclusion: Upright stance accelerates cervical disc degeneration in rats. [ABSTRACT FROM AUTHOR]