Effect Of Zoledronic Acid On Osteoprotegerin/ Tumor Necrosis Factor α MRNA Expression

ObjectiveTo observe the effect of zoledronic acid on the proliferation, differentiation and the mRNA expression of osteoprotegerin(OPG) and tumor necrosis factorα(TNFα) of rat osteoblasts, and to probe its role in bone metabolism, thereby to provide evidence for promote osteoporotic bone healing.MethodsThe osteoblasts isolated from the calvaria of neonatal SD rats were cultured with different concentrations of zoledronic acid.The final concentration of zoledronic acid in the experimental group ranged from 10^-5～10^-9.However,rats in the control group were given the same volume of cell suspension and culture media.At day 3,5,and7 after zoledronic acid intervention, MTT colorimetric assay was used to measure the absorbance to detect the effect of zoledronic acid on the proliferation of osteoblasts.On the 3rd days, p-nitrophenyl phosphate approach method was used to detect the activities of alkaline phosphatase,while RT-polymerase chain reaction was used to detect osteoprotegerin / tumor necrosis factorαmRNA expression.Results1.Observing and identification of osteoblasts: we can found from inverted phase contrast microscope that all cells were cultured by 48h after cell inoculation when adherent cell colonies formed, adherent growing cells display triangle, longspindle and polygon. By alkaline phosphatase (ALP) staining, the majority of cells are visible brown-black granules. When the cells begin calcification, it is the time to stain alizarin bordeaux, then we can found the red nodules.2.Zoledronic acid at the concentration of 10^-5mol/L could inhibit the proliferation of osteoblasts,but it had no effect at concentration of 10-6～10^-9mol/L.Zoledronic acid at concentration of 10^-7～10^-9mol/L could not influence the activities of alkaline phosphatase.3.Zoledronic acid at concentration of 10^-5～10^-9mol/L could up-regulate the osteoprotegerin mRNA expression,and down-regulate tumor necrosis factorαmRNA expression.ConclusionZoledronic acid at low concentration cannot influence the proliferation and differentiation of osteoblasts;whereas, it can inhibit bone resorption by regulating the OPG/ TNFαmRNA expression.