Therapeutic effect of aqueous extract from Ecliptae herba on bone metabolism of ovariectomized rats

Objective: Ecliptae herba (EH) has long been used in China to strengthen bones. Accumulating evidence indicates that EH may have antiosteoporotic effects. The aim of this study was to evaluate the effects of aqueous EH extract (EHE) on rats that had osteoporosis-like features induced by ovariectomy, using aqueous Fructus Ligustri Lucidi extract as positive control agent. Methods: Three-month-old female rats that underwent ovariectomy were treated with EHE (1.4 g/kg per day). After 12 weeks, bone mineral density and bone histomorphometric indices of tibiae were measured. Protein and messenger RNA expressions of osteoprotegerin and receptor activator of nuclear factor kappa-B ligand (RANKL) in tibiae were evaluated by immunohistochemistry and in situ hybridization. In addition, serum concentrations of osteocalcin, interleukin-1 beta, interleukin-6 (IL-6), calcitonin (CT), and parathyroid hormone were determined by enzyme-linked immunosorbent assay. Results: EHE treatment prevented body weight gain and loss of uterine wet weight in ovariectomized rats. It remarkably increased bone mass in ovariectomized rats compared with ovariectomized controls. EHE treatment significantly down-regulated RANKL expression in tibiae from ovariectomized rats compared with controls; however, it had no significant effect on osteoprotegerin expression. In addition, EHE treatment significantly reduced serum IL-6 levels and remarkably increased CT levels but had no effect on parathyroid hormone. Conclusions: EHE increases bone mass in ovariectomized rats by inhibiting bone loss: down-regulated RANKL expression in tibiae and IL-6 level in serum, and up-regulated CT level in serum. This suggests that EHE may be developed as an alternative therapeutic agent for osteoporosis induced by postmenopause.