BIOMOLECULAR STUDY ON DEGENERATION OF INTERVERTEBRAL DISK OF SENESCENCE-ACCELERATED MICE

为探讨TGF-βs、骨形态发生蛋白（BMP）及其受体在加速衰老小鼠（SAM）椎间盘退变过程中的生物学作用，采用免疫组织化学方法，对SAM椎间盘内TGF-βs、BMP及其受体的时空分布进行了研究。50周龄时，核内的脊索细胞减少并被纤维组织所取代。纤维环玻璃样变粗。终板生长软骨层变薄，可见骨和血管向软骨层浸润。Epipyseal环显示骨赘样形成。BMP及其受体在8和24周龄椎骨终板内的透明软骨细胞中丰富。然而，BMP及其受体的表达从椎体终板的透明软骨转移到纤维环内的纤维细胞和50周龄小鼠的附着点处的钙化软骨。SAM小鼠椎间盘TGF-βs及其受体在8周龄时即有表达，随增龄而减弱。BMP和TGF-βs在椎间盘退变中可能起一定作用。

Temporal and spatial immunolocalization of TGF-βs, bone morphogenetic protein (BMP) and their receptors in the intervertebral disk of senescence-accelerated mice (SAM) were examined to determine the biological roles in the process of the degeneration in intervertebral disks. At 50 weeks of age, notochordal cells in the nucleus decreased and replaced by fibrous tissue. The fibers of annulus showed hyalinization and coarsening. The growth cartilage layer of the endplate become thinner and infiltration of bone and blood vessel into the articular cartilage layer was observed. Epipyseal ring showed osteophyte like formation. BMP and its receptors were abundant in hyaline cartilaginous cells within the end-plate of the vertebrae at 8 and 24 weeks of age. However, the expression of BMP and its receptors moved from the hyaline cartilage of the end-plate of the vertebrae to fibrous cells within the annulus and to the calcified cartilage at the site of enthesis of mice aged 50 weeks. Expression of TGF-βs and its receptors in disk of SAM mice was observed at 8 weeks of age, and became weaker with aging. BMP and TGF-βs might play roles in degenerative change of intervertebral disk.