探討血栓素A2合成酶抑制劑對老年小鼠骨質密度的影響

To Evaluate the Effects of Thromboxane A2 Synthase Inhibitor on the Bone mass of Senile mouse

俞曉頴(Hsiao-Ying Yu)

指導教授 ： 林淑容

中原大學/工學院/生物科技研究所/碩士(2013年)

https://doi.org/10.6840/cycu201301112

摘要

骨質疏鬆症是停經後婦女與老年人重要的健康議題之一，臨床上並無明顯症狀，但會因輕微創傷而引發骨折及相關併發症，嚴重影響病患的生活品質和生命。過去研究發現人類遺傳性疾病Ghosal hematodiaphyseal dysplasia syndrome (GHDD)患者因thromboxane A2 synthase (TXAS) 基因發生突變，使得thromboxane A2 (TXA2)產量減少，進而造成患者骨質密度明顯增高，進一步實驗發現TXA2會調控成骨細胞的基因表現而影響骨生成；顯示藉由服用TXAS抑制劑抑制TXA2的合成，可望改善骨質疏鬆症。本論文採用 10 個月大之自然老化雄性小鼠作為老年骨質疏鬆症動物模式；實驗共分三組，分別為空白組(於管餵實驗開始前即犧牲)、對照組(管餵 ddH2O)及實驗組(管餵TXAS抑制劑；TXAS-I，5mg/kg/day)；餵食十六週後犧牲，取血漿、骨髓細胞及股骨進行分析。實驗結果發現在骨質密度、骨小樑體積、骨小樑厚度及骨小樑數目等指標，實驗組與對照皆低於空白組，且對照組與空白組相比具顯著差異；而血清睪固酮之含量，各組間皆無顯著差異；骨髓細胞之基因表現分析顯示，對照組之mPGES-1表現高於空白組及實驗組，而發炎因子IL-1β的基因表現量也高於空白組，另外，TNFRSF11B (OPG) 的基因表現量在實驗組也顯著高於空白組。本實驗結果顯示，對照組之骨質量因老化而流失較多，而實驗組的骨質流失則較為輕微。骨髓細胞中骨回收及骨生成相關因子之基因表達量，對照組之骨回收指標表現較高，實驗組則表現較高之骨生成因子，因此推測TXAS抑制劑可能是藉由降低骨回收因子的表現或提高骨生成因子之表現，達到減緩老化引起之骨質流失。

關鍵字

thromboxane A2 synthase ； 骨質疏鬆症 ； 老化

並列摘要

Osteoporosis is an important health issue in postmenopausal women and elderly persons. Although there are no obvious clinical symptoms, minor trauma may cause fractures and other related complications which may severely impact on patients' life quality and life span. Ghosal hematodiaphyseal dysplasia syndrome (GHDD) is a disorder with higher bone density. Genetic studies of patients with this disorder had identified mutations in the gene encoding thromboxane A2 synthase (TXAS), which is the key enzyme for producing thromboxane A2 (TXA2). TXA2 was indicated to be involved in the maintenance of bone homeostasis. According to these results, TXAS inhibitor may be a good therapeutic candidate for treating osteoporosis. To prove this, ten month-old senile male mice were used as a senile osteoporotic animal model. The mice were divided into three groups: baseline (sacrificed before treatment)、control (ddH2O), and TXAS-I (TXAS inhibitor: 5mg/kg/day). After 16 weeks treatment, long bone was fixed, decalcified, and sections were collected for H&E stain. Micro-CT scan was used for BMD analysis and trabecular parameters measurement. The mRNA level of bone marrow cells flushed from the femur were determined by quantitative RT-PCR. Our results demonstrate that the femur BMD, percentage of bone volume, trabecular thickness and trabecular number are significantly lower in the control group, when compared with baseline group. Serum testosterone in three groups does not show any significant differences. The expression of mPGES-1 in control group is higher than baseline group and TXAS-I group. IL-1β in control group is significantly higher than baseline group. And TNFRSF11B (OPG) mRNA expression in the TXAS-I group is significantly higher than baseline group. These results demonstrate that the aging-accelerated bone loss in control group is severer, while the bone loss in TXAS-I group is minor. And bone marrow cells of the control group express higher bone resorption markers, while those of the TXAS-I group express higher bone formation markers. Thus, we suggest that the uptake of TXAS inhibitors may ameliorate aging-accelerated bone loss through increasing the expression of bone formation markers or decreasing the expression of bone resorption markers in bone marrow cells.

並列關鍵字

thromboxane A2 synthase inhibitor ； osteoporosis ； senile mice

參考文獻

行政院衛生署國民健康局，2011，骨質疏鬆症臨床治療指引

楊榮森，2008，老年人的跌倒與骨折預防，台灣老年醫學暨老年學雜誌3卷2期

劉宜旻，2011，探討isoflavone和ozagrel對卵巢切除小鼠骨代謝的影響

Boyce, B. F. and L. Xing (2008). "Functions of RANKL/RANK/OPG in bone modeling and remodeling." Arch Biochem Biophys473(2): 139-146.

Boyle, W. J., W. S. Simonet, et al. (2003). "Osteoclast differentiation and activation." NATURE423(6937): 337-342.