Objective       To determine the effects of Cynomorium Songaricum polysaccharide (CSP) on the osteoporotic (OVX) rats by ovariectomization.       Methods       Female SD rats were randomly given sham operation or ovariectomization

and then the model group were further divided into model group

positive control groups

and CSP treatment groups. The rats from the CSP treatment group were fed in

tragastrically with CSP at a dose of 20

40 and 80 mg/kg

respectively

and those of the positive control group were with nilestriol (1.5 mg/kg) respectively

with 10 rats in each dose group

once per day for 12 consecutive weeks. The serum contents of estradiol (E

2

)

boneglaprotein (BGP)

calcitonin (CT) and urinary deoxypyridinoline(DPD) were detected by enzyme linked immunosorbent assay (ELISA). The bone mineral density (BMD) in the lumbar spine and femur was analyzed by dual energy X-ray absorptiometry (DEXA)

and bone biomechanical properties of tibia were measured by the three-point bending test. The expression of osteoprotegerin (OPG) and receptor activator of NF-κB ligand (RANKL) in the femur was analyzed by Western blotting.       Results       Compared with the sham operation group

the serum levels of E

2

and CT were significantly decreased (P0.05

P0.01)

while the contents of BGP and DPD were significantly increased (P0.01) in the OVX rats. While

the medium and high doses of CSP and nylestriol significantly elevated E

2

and CT (P0.05)

and decreased BGP and DPD (P0.01). The CSP and nylestriol reversed the reduction of BMD in the lumbar spine and femur (P0.01)

effectively improved the tibial maximum load and maximum stress (P0.05

P0.01)

enhanced the expression of OPG (P0.05

P0.01)

lowered the level of RANKL protein (P0.01). and elevated OPG/RANKL ratio (P0.01).       Conclusion       CSP exerts potential antiosteoporotic effects on OVX induced postmenopausal osteoporosis. The mechanism may be related to the regulation of E

2

CT

BGP and DPD

and activation of OPG/RANK/RANKL signaling system.