OBJECTIVETo explore the effects and related mechanisms of total flavone of epimedium treatment(TFE)on primary callus for mation in ovariectomized rats.

METHODSForty male SD rats weighted from 209 to 246 g and aged 6 to 8 weeks were selected. Six weeks after ovariectomy a femur fracture model with middiaphyseal segment fracture was established, estimated and randomly divided into TFE group (150 mg·kg⁻¹·d⁻¹) and control group(received saline). HE staining was used to evaluate the morphologic difference of primary callus during the bone callus healing between these two groups. The relative expression of Runt-related transcription factor 2(Runx2) mRNA in the callus was identified by real-time polymerase chain reaction. Immunohistochemical technique was used to observe the Casein kinase 2-interacting protein 1(CKIP-1) protein level in the callus of the two groups. Maximum fracture load was tested by three point bend test.

RESULTSThe BMD, primary callus volume, trabecular member(Tb.N) and trabecular thickness(Tb.Th) were higher in TFE group than that in control group(<0.001). The Tb.N and Tb.Th of primary callus were higher in TFE group than control group (=0.001). The volume and bone volume/tissue volume of primary callus were in TFE group than control group(<0.01). The trabecular separation(Tb.Sp) of primary callus were in control group higher than TFE group(<0.01). The HE staining of the 6 week slices showed that the degree of cartilage ossification in callus of the TFE group was significantly higher than that in control group under high magnification. Real-time PCR revealed that the comparative expression of Runx2 mRNA in control group was higher than that in TFE group(<0.001); the positive number of CKIP-1 was less in TFE group than that in control group (<0.001). TFE could increase the maximum load of the primary callus (<0.001).

CONCLUSIONSTFE can promote the cartiage ossification of callus in ovariectomized rats, enhancing the bone strength and bone quality in the process of fracture healing via the CKIP-1/Runx2 pathway.