[Objective]To investigate the effects of different concentrations of astragalus polysaccharide on osteoporosis induced by reti-noic acid in rats.[Methods]Fifty SD rats were randomly divided into control group,model group,low-dose group,medium-dose group and high-dose group,with 10 rats in each group.Except the control group,the other groups were given 70 mg/kg retinoic acid continuous intra-gastrically for 18 days,and the control group was given equal volume distilled water.After that,astragalus polysaccharide was given intragas-trically,100 mg/kg in the low dose group,200 mg/kg in medium dose group and 400 mg/kg in high dose group,whereas equal volume of dis-tilled water was given in the control group and model group.At 30 days after administration,gross measurement,BMD and biomechanical tests were performed on the left femur of rats.Serum concentrations of TNF-α and TGF-β1 and bone homogenate protein were measured.[Results]The femur weight in descending order was control group＞high dose group＞medium dose group＞low dose group＞model group[(1.1±0.2)gvs(1.0±0.1)gvs(0.9±0.2)gvs(0.8±0.1)gvs(0.6±0.0)g,P＜0.001],with no significant difference in bone weight between control group and high-dose group(P＞0.05).BMD was ranked as control group＞high dose group＞medium dose group＞low dose group＞model group[(252.5±21.2)mg/cm2 vs(232.7±21.4)mg/cm2 vs(190.6±31.2)mg/cm2 vs(158.1±13.1)mg/cm2 vs(119.9±12.2)mg/cm2,P＜0.001],and there was no significant difference in BMD between the control group and the high-dose group(P＞0.05).The order of maximum load in mechani-cal test was the same as above,with statistically significant differences among groups(P＜0.05).The order of serum TNF-α detection was of control group＜high dose group＜medium dose group＜low dose group＜model group,with statistically significant differences among them(P＜0.05).The order of serum TGF-β1 was of high dose group＞control group＞medium dose group＞low dose group＞model group,with statistically significant differences(P＜0.05).Bone homogenate measured BMP-2/β-actin and P-ERK/ERK were as follows:control group＞high dose group＞medium dose group＞low dose group＞model group,with statistical significances(P＜0.05).[Conclusion]Astragalus polysaccharide can improve the osteoporosis induced by retinoic acid in rats,and its mechanism may be the activation of the downstream MAPK/ERK signal-ing pathway.
astragalus polysacchariderat osteoporosistumor necrosis factor-α(TNF-α)transforming growth factor-β1(TGF-β1)MAPK/ERK signal path
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