[Effect and mechanism of total flavone of epimedium on primary callus formation in ovariectomized rats with fractures].

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

METHODS: Forty 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.

RESULTS: The BMD, primary callus volume, trabecular member(Tb.N) and trabecular thickness(Tb.Th) were higher in TFE group than that in control group( P <0.001). The Tb.N and Tb.Th of primary callus were higher in TFE group than control group ( P =0.001). The volume and bone volume/tissue volume of primary callus were in TFE group than control group( P <0.01). The trabecular separation(Tb.Sp) of primary callus were in control group higher than TFE group( P <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( P <0.001); the positive number of CKIP-1 was less in TFE group than that in control group ( P <0.001). TFE could increase the maximum load of the primary callus ( P <0.001).

CONCLUSIONS: TFE 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.