Experimental study on the protective effect of EPO in glucocorticoid-induced osteoporosis / 中华骨科杂志

ABSTRACT

Objective:To study the mechanism of protective effect of erythropoietin (EPO) on glucocorticoid-induced osteoporosis in rats through promoting vascular action mediated by VEGF, promoting osteogenesis, and inhibiting bone resorption.Methods:An animal experiment of 24 SD rats in total were divided into three groups the osteoporosis group (20 mg/kg BW of methylprednisolone biwim for 6 weeks); the EPO group (MP 20 mg/kg biw+EPO 500 u/kg qdim); the nature salt group (0.9%NS). After 12 weeks, rats were harvested and received examination of histology (HE staining) for demonstration of protective effect, immunohistochemistry with CD31 stainingfor microvascular changes ,changes of VEGF and PCNA expressions using Western Boltfor microvascular and cell proliferation, and ELISA to detectOPN, PINP, CTX-1 in serumasbone turnover marker.Results:Hematoxylin and eosin staining in the model group showed that the bony trabeculae had become obviously narrow and sparse with discontinuity of the integrity. The integrity of the trabeculae was better in the EPO group. Immunohistochemical results: the EPO group CD31+ cell 16.60±4.88, the osteoporosis group 12.96±4.54, the NS group 25.84±7.97. CD31 expression was higher in the EPO group than the osteoporosis group. Western Bolt in the NS groupthe ratio of VEGF/β-actin greyscalewas 0.570±0.022, with the osteoporosis group 0.446±0.083 and the EPO group 0.584±0.009; The ratio of PCNA/β-actingreyscale was 0.541±0.158 in the NS group, withthe osteoporosis group 0.187±0.099, the EPOgroup 0.733±0.257. VEGF and PCNA expression in the EPO group were higher than those in the osteoporosis group. ELISA OPN results: the NS group 78.34±17.28 pg/ml, the osteoporosis group 368.48±97.23 pg/ml, the EPO group 217.62±39.11 pg/ml; P1NP results: the NS group 1 507.00±58.49 ng/ml, the osteoporosis group 1 196.00±91.32 ng/ml, the EPO group 1 621.00±65.57 ng/ml; CTX-1 results: the NS group 27.10±4.78 ng/ml, the osteoporosis group 39.46±9.23 ng/ml, the EPO group 31.17±4.11 ng/ml. The level of OPN and CTX-1 in the EPO group were lower than that in the osteoporosis group, and P1NP was higher than that in the osteoporosis group.Conclusion:EPO generates certain protective effect on bone of rats withglucocorticoid-induced osteoporosis. Its potential mechanism is to promote vascular action, promote osteogenesis, and inhibit bone resorption.