Abstract: Objective To explore whether OK could ameliorate the OP in the castration OP tree shrew model. Methods Forty-eight female experimental tree shrews were randomly divided into control group (n = 8), OP model group (n = 8). The animals were removed bilateral ovaries (detecting a 25% decline in whole body BMD), and received saline by gavage daily. The tree shrews in OK-L (n = 8), OK-M (n = 8) and OK-H (n = 8) group were given the OK 0.5 mL/d, 1.5 mL/d and 3.0 mL/d of OK by gavage, tree shrews in positive control (n = 8) group were given the Premarin 1.5 mL/d, all the tree shrews were sacrificed 10 weeks later, the serum and bone were collected, the serum E2, Ca2+, P3+, BGP, ALP, the urine Ca, P, and the BMD were measured; RT-qPCR and Western blotting were used to detect the expression level of OPG, RANKL and RUNX2. Results Low，medium and high dose of OK can increase the E2, Ca2+, P3+, ALP levels in serum significantly，and reduce the Ca, P levels in serum and the BGP level in serum; As well as upregulating the expression levels of OPG and RUNX2, downregulating the expression level of RANKL. Conclusions OK can increase the secretion of E2, inhibit bone resorption and enhance bone formation, and increase the BMD to alleviate the OP.

Key words: Tree shrew, Osteoporosis, Osteoking, Differentiation of Osteocyte