Research On The Stimulating Osteoblast Differentiation And Its Molecular Mechanisms Of Astragaloside Ⅰ

Bone is a kind of dense connective tissue,which can protect the body by storing minerals,regulating the mineral balance,meanwhile,hematopoietic cells are generated in the bone.Bone is an updating tissue.Its dynamic balance is mediated by osteoblast and osteoclast.The imbalance is the basic reason of osteoporisis.Osteoporosis(OP)is a generalized skeletal disorder characterized by a decrease in bone mass and density,and then lead to an increased fracture risk.It is prevalent in old aged people and lead to significant decrease in living quality.Up to date,OP has become the major health concerns in the aging society.Finding a new drug which can cure OP has become an urgent affair.Astragali radix is the root of Astragalus membranaceus(Fisch.)Bge.var.mongholicus(Bge.)Hsiao or EE Astragalus membranaceus(Fisch.)Bge.Astragali radix has a range of bioactivities,such as anti-inflammation,antioxidant properties,immune-enhancing effect,and so on.It was reported that Astragali radix can prevent and treat steroid osteoporosis,its extracts,and compounds were useful for osteoporosis.It is reported tat Astragaloside I(As-I),one of the main active ingredients in Astragali Radix,can improve the osteogenesis ability and ALP excretion of BMSCs.However the mechanism of its effect on osteoblast differentiation has not yet been investigated.In this study,we investigated the effect of As-I on osteoblast differentiation,and its mechanism.The experimental result showed that:(1)As-I(10,20,40μM)has no effect on the cell proliferation and has no toxic effect for the cells.(2)At the concentration,As-I can stimulate the ALP activity and promote matrix mineralization in MC3T3-E1 cells.(3)The expression of the marker gene of Wnt pathway,β-catenin and Runx2,are upregulated by As-I.Meanwhile,the Wnt pathway inhibitor Dkk-1 can inhibit the ALP activity and gene expression of β-catenin,which were stimulated by As-I(4)As-I can stimulate the osteoblast marker gene BMP-2,BGP mRNA and protein expression.(5)As-I can stimulate OPG mRNA and protein expression,while inhibit RANKL mRNA and protein expression.Taken together,the study showed that As-I can stimulate the osteoblasts differentiation through Wnt pathway.It also improved that As-I can promote BMP-2 and BGP expression,which demonstrate that the effect of As-I on osteoblasts differentiation through BMP pathway.Further more,our date demonstrated that As-I can downregulate the RANKL/OPG ratio,which might inhibit the osteoclasts differentiation.