The in vivo effects of a fraction from Dioscorea spongiosa on glucocorticoid-induced osteoporosis

In traditional Chinese medicines, osteoporosis was considered to be induced by the deficiency of kidney's function. The Rhizoma of Dioscorea spongiosa was one of the kidney tonifying and bone strengthening agent in the traditional usage and previous study had shown that its 90% ethanol fraction was effective on anti-osteoporosis using the ovariectomized (OVX) rats. However, for the secondary osteoporosis, like glucocorticoid-induced osteoporosis (GIO), its effect was still unknown.The GIO model was established by injecting dexamethasone into the muscles of rats. The 90% ethanol extraction of Dioscorea spongiosa (DSE) were administrated to rats in three different dosages, 125, 250 and 500mg/Kg/d, respectively. After the administration, the rats were sacrificed to measure different kinds of indicators, including the biochemical indexes in urine and serum, the bone tissue metrology, BMC and BMD, biomechanical indicators and histological changes.DSE could significantly reduce the content of BGP, ALT, TRAcP, HOP/Cr and Ca/Cr, increase the content of P/Cr compared with the control group, suggesting that DSE is effective on controlling the excessive transition of bones and inhibiting the bone resorption. By the administration of DSE, the dry bone weight/volume, ash weight/volume, the content of Ca, BMD and BMC were also obviously increased, suggesting that DSE could increase the bone mass by increasing its Ca content. Besides, the flexure strength and maximum bending force could be improved by DSE, suggesting that it could strengthen the hardness and strength of bones. In the histological investigation, DSE could repair the broken of cancellous bones and bone trabecular with the similar activity with XLGB.The results showed that DSE is effective on inhibiting GIO in rats by improving the bone tissue metrology, BMC and BMD as well as biomechanical indicators, and also repairing the microscopic changes of cancellous bones and trabecular bones. The mechanism was related to the inhibition of excessive bone transition and bone resorption according to the changes of biochemical indexes.