mRNA levels of proteins related to bone metabolism in the experimental osteoporosis of rats.

人类骨质疏松症的病因是多因素的，并且可以由诸如衰老、绝经后和固定等条件以及全身内分泌激素和局部生长因子和细胞因子的变化引起。本研究采用去势结合制动诱导雌性Wistar大鼠实验性骨质疏松模型，研究骨代谢相关蛋白质的mRNA水平。进行双侧坐骨神经切除术以恢复后肢。大鼠口服1，25（OH）_2D_3或新合成的维生素D_3类似物2-（3-羟丙氧基）-1，25-二羟维生素D_3 [艾德-71]，每周2次，分别于第1、2、4和8周处死。骨矿物质含量在艾德-71 0.2 μ g/kg给药组中得以保留。在第4周和第8周，1，25（OH）2D 3 0.2 μ g/kg和艾德-71 0.2 μ g/kg治疗组的血清骨钙素水平升高。通过北方印迹杂交测定的后肢骨中的骨钙素mRNA水平在艾德-71 0.2 μ g/kg处理组中持续增加。结果表明，艾德-71不仅通过促进骨吸收，而且通过刺激成骨细胞来防止骨吸收的减少，在体外实验中，当1，25（OH）_2D_3或艾德-71加入到培养液中时，骨钙素mRNA水平以剂量依赖的方式增加。当细胞暴露于26，27-F6- 1，25（OH）2D 3 [F6-D3]（1，25（OH）2D 3的类似物）时，细胞的骨钙素mRNA水平增加。1，25（OH）_2D_3和F_6-D_3均可使细胞碱性磷酸酶和骨桥蛋白mRNA表达增加。总之，1，25（OH）2D 3和两种类似物直接刺激骨钙素、碱性磷酸酶和骨桥蛋白mRNA的表达。

Human osteoporosis is multifactorial in its etiology, and can result from such conditions as senility, post-menopause and immobilization, as well as changes in endoclinological hormones at general and growth factors and cytokines at local sites. We investigated the mRNA levels of proteins related in bone metabolism.Experimental osteoporosis was induced by a combination of ovariectomy and immobilization in female Wistar rats. Bilateral sciatic neurectomy was performed in order to immobilize the hind limbs. Rats were orally given 1,25 (OH) 2D3 or a new synthetic vitamin D3 analogue, 2- (3-hydroxypropoxy) -1,25-dihydroxyvitamin D3 [ED-71] twice a week and sacrificed at 1,2,4 and 8 weeks. Bone mineral content was preserved in the ED-71 0.2mug/kg treated group. Serum osteocalcin levels increased in the 1,25 (OH) 2D3 0.2mug/kg and ED-71 0.2mug/kg treated groups at 4 and 8 weeks. Osteocalcin mRNA levels in the bones of the hind limbs which was determined by Northern blot hybridization and increased consistently in the ED-71 0.2mug/kg treated group. These findings suggest that ED-71 may prevent the osteoporotic decrease of bone mass not only by normalizing bone resorption but also by stimulating osteoblasts.In the in vitro experiment using rat osteosarcoma cells (ROS 17/2.8), osteocalcin mRNA levels increased in a dose-dependent manner when either 1,25 (OH) 2D3 or ED-71 was added to the medium. Osteocalcin mRNA levels of the cells increased when they were exposed to 26,27-F6-1,25 (OH) 2D3 [F6-D3], (an analogue of 1,25 (OH) 2D3). Alkaline-phosphatase mRNA and osteopontin mRNA in the cells also increased when either 1,25 (OH) 2D3 or F6-D3 was added to the medium. In summary, 1,25 (OH) 2D3 and two analogues directly stimulated osteocalcin, alkaline-phosphatase and osteopontin mRNA expression.