Objective: To explore the cell signal mechanism of osteoporosis prevented by icariin. Methods: thirty-six female wirst rats
were randomly divided into 3 groups: the OVX group(ovariectomize); the OVX-I group(OVE and treated with icarrin) and the OVX-E group(OVE and treated with estradiol). The plasma alkaline phosphatase(ALP) was determined four, six, eight weeks after the surgery and the animal body weight was measured eight weeks after the surgery then the shaft of femur was separated and cultured tothe
osteoblast. RT-PCR was employed to detect the Smad4 mRNA level of osteoblast in all three groups. Results: (1)The body weight
increase could be inhibited by injection of icariin.(2)The increase of ALP level in the OVX-Ⅰ and OVX-E group had no statistical significance four, six weeks after surgery but ALP increase in the OVX group was statistically significant compared with two others (P < 0.01), the ALP level decreased in onoler of the OVX, OVX-I and OVX-E group eight weeks after surgery, the difference was statistically significant(P < 0.01). (3)The level of the Smad4 mRNA increased in order of the OVX,OVX-I,OVX-E group detected by RT-PCR eight weeks after surgery, especially in the OVX-E group. Conclusion: Icarrin can inhibit the amount of ALP increase in the OVX rat and reduce the rat body weight by increasing Smad4 mRNA.