| Summary: | 碩士 === 中國醫藥大學 === 基礎醫學研究所碩士班 === 101 === 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.
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