| Osteoporosis is recently focused as one of" the important endocrine diseases. With the coming of the elderly society, this disease has become a significant factor affecting the living quality in senile populations. Some of the drugs to treat osteoporosis are present but seldom of them can be demonstrated to possess the direct effect on promoting the proliferation of osteohlast.Vanadium, a transition element of VD family in the periodic list of chemical element, widely exists in the earth. This element participates in many physiological processes in human body such as the growth and differentiation of cells, metabolism of carbohydrates and lipids. It is also reported that vanadium has insulin-mimetic activity. In the recent published data, vanadium showed the effects of promoting bone formation and inhibiting bone rcsorption. Nitric oxide is proved as an important signal molecule in the processes during the bone formation and resorption. NO with low or high levels can promote or suppress bone formation, respectively. In the previous reported literatures, the signal of estrogen onpromoting bone formation was transferred through NO. However, it is little understood that the effect of vanadium on osleoblast is regulated with NO or not.In this study, sodium orthovanadate as a representative of vanadium and mouse MC3T3-E1 cell line as a cell model were used to determine vanadium effect on MC3T3-E1 cells and NO mediation.Objective: To demonstrate the effects of sodium orthovanadate on promoting proliferation and differentiation for MC3T3-E1 cells and the action of nitric oxide (NO) mediating the effects.Methods: Mouse MC3T3-E1 cell line was used as the osteoblast model. Proliferation promotion induced by sodium orthovanadate and proliferation inhibition caused by L-NAME for the cells were determined by MTT assay. Coomassie blue method was employed to measure the protein contents in the cells. Cellular ALP activity was examined by using commercial ALP Detection Kit. The level of NO in the supernatant of cell culture was detected by enzyme reduction method for finding the action of NO in the process.Results:1. Sodium orthovanadate with low or high concentrations could promote or inhibit the proliferation of MC3T3-E1 cells. The results of MTT assay showed that the 00490 values of MC3T3-E1 cells treated with sodium orthovanadate at a concentration range of 2.5-10 (.imol/L for 24 h were significantly increased compared with the blank control (P < 0.001) . When 50 and 100 mnol/Lof sodium orthovanadate used for 24 h, the OD490 values of the cells were much lower than that of the blank control (P < 0.001) . Similar results were found in the cells treated with sodium orthovanadate for 24, 48 and 120 h, respectively.2. Sodium orthovanadate at different concentrations could decrease the cellularALP activity. The results of ALP activity measurements indicated that the ALP activities of MC3T3-E1 cells treated with 10 and 100 mol/L of sodium orthovanadate were remarkably decreased in comparison with the blank control (P <0.05, P< 0.001) .3. Significant enhancement of NO levels in the cells treated by sodium orthovanadate at low concentrations was found. The results of NO concentration detection demonstrated that the NO levels in the supernatants of MC3T3-E1 cells acted by 0.5, 2.5 and 5 umol/L of sodium orthovanadate for 24 h was obviously increased compared with the control (P < 0.001). On the contrary, the NO levels in the supernatants showed remarkable decreases after the cells were treated with sodium orthovanadate at the higher concentrations of 10, 25, 50 and 100 umol/L, respectively (P < 0.001).Conclusion:1. Sodium orlhovanadate at the lower concentrations (2.5-10 umol/L) can promote MC3T3-E1 cell proliferation.2. Sodium orthovanadate at the different tested concentrations can inhibit the MC3T3-E1 cell differentiation.3. The effect of the cell proliferation is probably induced by nitric oxide. |
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