AIMTo investigate the effects of water extract fractio n from Salvia Miltiorrhixa Bunge (DWE) and its bioactive compound danshensu on p rednisone-induced osteoporosis in rats and to examine the effect of DWE and dan shensu on activity of ALP in rat primary cultured osteoblasts. METHODSStudy 1: Thirty-two 4-month-old SD rats were randomly divided into four groups: ①intact rats was given with vehicle as control (Intact + Veh); ②Predn isone was given orally to the rats at dose of 2 7 mg·kg -1 ·d -1 as the model group (Pred+Veh); ③ DWE at dose of 5 0 g·kg -1 ·d -1 were added to the prednison treated rats (Pred+DWE) ; ④Conbined medicine (Stanozolo l 0 5 mg·kg -1 ·d -1 +VitD 3 25 IU·kg -1 ·d -1 +Calcium 0 5 g·kg -1 ·d -1 ) were added to the prednison treated rats (Pred+SD C). Double in vivo fluorochrome labeling was performed before killing the rats. The undecalcified longitudinal proximal tibial metaphyseal section were used to do bone histomorphometric analysis. The right ulna was used to test the bone cal cium content and bone hydroxyproline content. Study 2: New born SD rat calvarium osteoblasts were cultured in DMEM alone or exposed to different concentration o f DWE or danshensu for 2 and 10 days respectively, the activity of alkaline phos phatase (ALP) was detected with enzyme-chemistry method.
RESULTSCompared with control group, trabecular bone volume and bone formation rate/TV in prednisone treated group dec reased by 41 3% (P<0 01) and 39 9% (P<0 01) respectively, osteoclast surface increased significantly accompanied with decrease of bone calcium and h ydroxyproline contents. The prednison plus DWE group was completely prevented fr om bone loss and showed increased bone formation rate and decreased osteoclast s urface when compared with prednison alone. The effects of DWE on the bone dried weight and bone organic content (hydroxyproline) were better than that of combi ned medicine treated group. DWE (the concentration from 0 5 to 10 0 g ·L -1 ) and danshensu (the concentration from 0 1 to 5 0 mg·L -1 ) increased ALP activity of rat cultured osteoblasts by two folds in a dose and time dependent manner. CONCLUSONDWE can protect trabecu lar bone loss from steroid-induced osteoporosis due to stimulating osteoblast a ctivity and decreasing osteoclast activity.