| Summary: | 碩士 === 義守大學 === 化學工程學系暨生物技術與化學工程研究所 === 102 === Bone tissue destruction is the features of many symbolic diseases, including osteoporosis, rheumatoid arthritis and bone metastasis. It is the result of joint pain and bone deformities. Bone development in vertebrate animals is maintained by two coordinated actions of osteoblast and osteoclast. Receptor activator of nuclear factor-κB ligand (RANKL) has been identified as osteoclast differentiation and activation of an important factor. As such, the down-regulation of RANKL expression or its downstream signals may be a valuable approach to the treatment of pathological bone loss. Siegesbeckia orientalis Linne has been used in traditional rheumatoid arthritis and adjuvant treatment of high blood pressure. This study investigated the inhibitory effects of S. orientalis ethanol extract (SE) on the RANKL-induced osteoclastogenesis of RAW264.7 cell and the survival of mature osteoclast cells. Experimental results showed that SE could effectively inhibit the RANKL-induced formation of osteoclasts and exhibited a dose-dependency on the TRAP activity. It can be seen from the TRAP-staining, after five-day cultivation of RAW264.7 cells with SE, the number of mature osteoclast cells decreased as the SE concentration increased. Additionally, SE inhibited pit formation on Osteo Assay Surface system in a dose-dependent manner that indicated its ability to inhibit the bone resorptive activity of mature osteoclasts in a RAW264.7 cells model. Western blot analysis demonstrated that SE could down-regulated the expression of TRAF6, p38, NF-κB, JNK, ERK, MMP-9 and downstream NFATc1 proteins. In addition, SE could induce the cell death of mature osteoclasts via the down-regulation of NF-κB, p38, JNK, ERK and NFATc1. Taken together, our findings clearly show that SE can attenuate RANKL-induced differentiation and formation of osteoclasts. Therefore, SE has a potential to become complementary agents for treating various bone diseases associated with excessive osteoclast formation and bone destruction. It is worth for further evaluation.
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