Objective: To observe the effects of alcohol extracted part A of Zhuanggu Zhitong prescription for treatment of osteoporosis

and to explore the possible mechanism. Method: Seventy five female SD rats weighing about 250 g were randomly divided into control group

model group (induced by ovariectomization)

sham operation group

ethanol extracted partA of Zhuanggu Zhitong prescription group (0.12 g ·kg-1 ·d-1) and Zhuanggu Zhitong prescription group (13.2 g ·kg-1 ·d-1). Five days after ovariectomization

different treatment were lasted for 13 weeks. Blood and bone samples of the rats were used to determine the bone mineral density

bone biomechanics

path-ology and other aspects to evaluate the efficacy.Serum (estrone) (E2)

bone gla protein(BGP)

parathyroid gland(PTH)

calcitonin(CT) were investigated for exploring the related mechanism. Result: Ethanol extracted part A of Zhuanggu Zhitong prescription showed significantly increase in femoral and lumbar bone mineral density (P<0.05);could significantly enhance the maximum stress and tibia maximum flexural strength (P<0.01); Ethanol extracted part A had an increasing trend of serum E2 and uterine wet weight. Ethanol extracted part A could significantly increase the average trabecular bone-density of the femoral head (P<0.01). Ethanol extracted part A could significantly decreasethe serum CT (P<0.01). Conclusion: The ethanol extracted part A can increase the bone density

the maximum stressand the maximum bending strength. Part A may reverse osteoporosis with improved pathological evidences.The mechanism may be related to estrogen-like action of the drug with improved hormone metabolism

regulated bone metabolism and cytokines

reduced bone turnover

bone formation and inhibited bone resorption.