[Effect of Epimedium extract on osteoprotegerin and RANKL mRNA expressions in glucocorticoid-induced femoral head necrosis in rats].

OBJECTIVE

To investigate the effect of glucocorticoid on the expression levels of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B ligand (RANKL) mRNAs in rat femoral head and the antagonistic effect of Epimedium, and explore the mechanism of Epimedium in preventing glucocorticoid-induced femoral head necrosis.

METHODS

Forty-eight adult SD rats were randomized into glucocorticoid group, Epimedium group and control group. In the former two groups, the rats received intramuscular injection of 12.5 mg prednisolone twice a week, and in Epimedium group, additional 1 ml/100 g aqueous Epimedium extract (equivalent to 0.1 g/ml of the crude drug) was administered intragastrically once daily. The control group received only intramuscular saline injection. After 4 weeks of treatment, osteonecrosis of the left femoral head was detected by HE staining, and the right femoral head was sampled for detection of OPG and RANKL mRNA expressions using real-time quantitative PCR.

RESULTS

In glucocorticoid, Epimedium and control groups, the mortality rate of the rats was 12.5% (2/16), 6.25% (1/16), 0 (0/16), and femoral head necrosis occurred at a rate of 71.43% (10/14), 26.67% (4/15), and 0 (0/16), respectively. In glucocorticoid group, the expression level of OPG mRNA was significantly lower, RANKL expression significantly higher, and OPG/RANKL ratio significantly lower than those in Epimedium and control groups (P<0.05). OPG, RANKL and their ratios showed no significant differences between Epimedium group and the control group.

CONCLUSIONS

Epimedium can prevent glucocorticoid-induced femoral head necrosis probably by antagonizing glucocorticiod-induced abnormal expressions of OPG and RANKL mRNA.