Mechanism of Youguiwan Regulating BMP-2/Smad Signaling Pathway to Promote Bone Formation in Postmenopausal Rats with Osteoporosis / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo observe the effects of Youguiwan on bone metabolism and bone morphogenetic protein-2 （BMP-2）/Smad signaling pathway in ovaries-removed rats with osteoporosis and study the mechanism of Youguiwan in the prevention and treatment of osteoporosis. MethodA postmenopausal rat model of osteoporosis was prepared by bilateral ovariectomy. The 40 female SD rats were randomly divided into five groups， including sham operation group， model group， alendronate sodium group （0.1 mg·kg-1）， and high-dose and low-dose （5.36 and 2.68 g·kg-1） groups of Youguiwan. The drug was given seven days after modeling， once a day for 12 weeks. After the treatment， the changes in femur tissue structure were observed by micro-CT， including bone mineral density （BMD）， bone volume/total volume （BV/TV）， trabecular number （Tb.N）， trabecular thickness （Tb.Th）， bone surface/bone volume （BS/BV）， and trabecular separation （Tb.Sp）. Ossification was observed by saffrane-solid green staining， and serum levels of bone metabolism markers， including bone alkaline phosphatase （BALP）， osteocalcin （BGP）， type Ⅰ procollagen amino terminal propeptide （PINP）， and tartrate-resistant acid phosphatase 5b （TRACP-5b）， were determined by enzyme-linked immunosorbent assay （ELISA）. The protein and mRNA expression levels of Runx2， BMP-2， and Smad1 in rat femur were detected by Western blot and Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR）. ResultCompared with the sham operation group， bone trabecula in the model group was sparse. BMD， BV/TV， Tb.N， and Tb.Th were decreased （P<0.05， P<0.01）. BS/BV （P<0.05） and Tb.Sp were increased. The content of BGP， BALP， PINP， and TRACP-5b in serum was significantly increased （P<0.01）. The mRNA and protein expressions of Runx2， BMP-2， and Smad1 in rat femur were significantly decreased （P<0.05， P<0.01）. Compared with the model group， the number of bone trabeculae in the high-dose and low-dose groups of Youguiwan was increased， and the bone microstructure was improved. BMD， BV/TV， Tb.N， and Tb.Th were increased significantly （P<0.05， P<0.01）， and BS/BV and Tb.Sp were increased. The content of bone metabolic markers decreased （P<0.05， P<0.01）. ConclusionYouguiwan has certain preventive and therapeutic effects on postmenopausal osteoporosis， and its mechanism may be related to promoting bone formation by regulating the BMP-2/Smad signaling pathway.