本研究是探討黃花石斛(Dendrobium tosaense)粗萃物(DT)的益生素效果以及對大鼠去卵巢所引起骨質疏鬆的作用。
去卵巢大鼠隨機分為四組:口服給予水、DT (300、900 mg/kg)、Inulin (400 mg/kg)，每天口服給予，持續14週。偽手術組口服給予水。給予DT可以增加去卵巢鼠糞便中的雙歧桿菌。鈣平衡試驗的結果顯示，DT可以明顯的增加鈣吸收以及鈣滯留的含量。去卵巢鼠給予藥物滿14週後犧牲。去卵巢鼠的骨鈣含量、骨礦物密度以及生物力學強度相較於偽手術組來的低， DT可以預防骨質的流失。微米級電腦斷層掃描造影系統顯示，大鼠給予DT可以增加骨小樑的含量比去卵巢鼠來的高。
細胞實驗方面證明了，DT的DTM100分層可以抑制蝕骨細胞的分化。以西方墨點法來分析RAW 264.7分化成蝕骨細胞的相關訊息傳遞路徑，結果顯示DTM100抑制由RANKL所誘導NF-κB核轉移以及抑制活化T細胞核因子c1。以反轉錄聚合?連鎖反應來分析RAW264.7分化成蝕骨細胞的骨吸收相關基因表達，DTM100抑制組織蛋白?k以及抗酒石酸酸性磷酸?。
結論，在動物研究提供的證據顯示，DT的益菌素活性參與抗骨質疏鬆的機轉。另外在細胞研究顯示出，DT可以直接抑制破骨細胞的分化。所以DT可能是一個具有治療停經後骨質疏鬆症的藥物。
The present study evaluated the prebiotic effect of Dendrobium tosaense extracts (DT) and its effects on osteoporosis in ovariectomized (OVX) rats. The OVX rats were randomly divided into four groups and orally treated with water, DT (300 and 900 mg/kg daily) and inulin (400 mg/kg daily) for 14 weeks. The sham group was orally treated with water. The DT treatment enhanced the number of faecal bifidobacteria in OVX rats. The results of a Ca-balance experiment showed that DT increased apparent Ca absorption and retention. The OVX rats were killed after DT treatment lasting 12 weeks. The mineral content, density and biomechanical strength of bones were lower in OVX rats than the sham group, but these bone loses were prevented by DT administration. Microtomography scanning showed that the DT-treated rats had higher trabecular bone volume than the OVX .
In vitro study demonstrated that DTM100 fraction from DT inhibited osteoclast differentiation. Western blot was used to analyze osteoclast-associated signaling pathway in RAW264.7 cells. Results showed that DTM100 inhibits the RANKL-triggered nuclear translocation of NF-κB and nuclear factor of activated T cells c1 (NFATc1). RT-PCR was used to analyze osteoclast resorption-associated gene expression in RAW 264.7 cells. DTM100 inhibits the expression of cathepsin K and TRAP.
In conclusion, In vivo studies provide evidence that prebiotic activity might be involved in the anti-osteoporotic mechanisms of DT. In addition, in vitro study also showed that DT could directly inhibit osteoclast differentiation. DT could be a potential candidate for the treatment of post-menopausal osteoporosis.
