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

为探讨转化生长因子-β、骨形态发生蛋白及其受体在加速衰老小鼠椎间盘退变过程中的生物学作用，对其进行了时空定位研究。50周龄时，细胞核中的脊索细胞减少，取而代之的是纤维组织。纤维环呈玻璃化、粗化。终板生长软骨层变薄，可见骨质和血管渗入关节软骨层。外耳环呈骨赘样形成。8周龄和24周龄时，椎体终板内的透明软骨细胞内有丰富的BMP及其受体。而50周龄的小鼠，BMP及其受体的表达从椎体终板的透明软骨转移到环内的纤维细胞和钙化的软骨。转化生长因子-βS及其受体在8周龄SAM小鼠腰椎间盘中有表达，且随着年龄的增长表达减弱。骨形态发生蛋白和转化生长因子-βS可能在腰椎间盘退行性变中起作用。

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.