地塞米松及补肾方药对大鼠骨维生素D受体表达的影响

摘要

Objective　To understand the mechanisms by which dexamethasone induces osteoporosis and Tonifying Kindey Recipe prevents dexamethasone-induced osteoporosis.Methods　Thirty six Wistar rats were divided into three groups: control group was injected with 0.9 % sodium chloride solution; dexamethasone group (DEX) and Tonifying Kindey Recipe group(TKR) were injected with dexamethasone (0.1 mg/100g weight) twice a week， and were administrated water and Tonifying Kindey Recipe (0.32 g/100 g weight) at the same time respectively.After 12 weeks the rats were killed and the total mRNA was extracted from bone. The expression of vitamin D receptor (VDR) was semi-quantified by RT-PCR.Results　The bone mineral density was decreased and the expression of VDR mRNA of the rats in DEX group was increased significantly. The bone mineral density of the rats in TKR was augmented and the expression of VDR mRNA was attenuated compared with DEX group.Conclusion　The up-regulating expression of VDR mRNA by dexamethasone may be one of the mechanisms by which dexamethasone induced osteoporosis.Tonifying Kindey Recipe may prevent dexamethasone-induced osteoporosis by down-regulating expression of VDR mRNA.%目的探讨地塞米松诱导大鼠骨质疏松症的机理及补肾方药预防其发生的机制。方法通过肌肉注射地塞米松造成骨质疏松模型，观察补肾中药灌胃对骨密度的影响，从骨骼中提取mRNA，采用RT-PCR方法对维生素D受体(vitamin D receptor,VDR）mRNA进行半定量。结果地塞米松组大鼠的骨密度明显降低，而骨骼中VDRmRNA 的表达却明显升高（P<0.05），与地塞米松组相比，补肾方药组的骨密度升高，VDRmRNA的表达降低（P<0.05）。结论地塞米松使VDRmRNA在骨骼的表达增强，这可能是其诱发骨质疏松症的机制之一；补肾方药可通过拮抗地塞米松的这种作用而防止骨质疏松症的发生。