Morin protects glucocorticoid-induced osteoporosis through regulating the mitogen-activated protein kinase signaling pathway.

Our aim is to investigate the potential therapeutic value of morin against osteoporosis and elucidate the mechanism of action. Osteoporosis was induced in rats by a subcutaneous injection of dexamethasone (DEX) for 5 weeks. Body weight was regularly monitored. Body mineral density (BMD) was determined at proximal femurs using dual energy X-ray absorptiometry. Pathological examination was performed by hematoxylin and eosin staining. The relative expression of osteogenic and bone resorption markers was determined by real-time polymerase chain reaction and Western blotting, respectively. Activation of the MAPK signaling pathway was analyzed by Western blotting. Body weight and BMD were both significantly decreased in osteoporotic rats, although BMD was partially restored by intraperitoneal morin administration. Morin treatment also increased the number of trabecular bones in DEX-induced rats. Mechanistically, morin reversed the decrease of osteogenic markers and increase of bone resorption markers, which might eventually be mediated by modulation of MAPK signaling cascades. Here, we uncovered the therapeutic effect of morin against osteoporosis and demonstrated its suppressive action on the MAPK pathway in this disease.