细胞增殖和DNA损伤在大鼠氟斑牙形成中的作用研究

Role of Cell Proliferation and DNA Damage in the Formation of Rat Dental Fluorosis Induced by Fluoride

目的:研究在氟中毒引起氟斑牙时,氟对大鼠切牙细胞增殖和DNA损伤的影响。方法:给雄性SD大鼠饮用含10,50,100mg/LNaF的高氟水60d和90d,制备氟斑牙模型,用流式细胞术检测大鼠切牙细胞增殖周期的变化,用单细胞凝胶电泳检测DNA损伤。结果:雄性SD大鼠饮用含50,100mg/LNaF的高氟水60d和90d,血清氟含量较对照组显著增高,P<0.05,具有较好的剂量-效应关系,相关系数分别为:0.9957(P<0.01)和0.9880(P<0.05)。在50,100mg/LNaF剂量条件下,大鼠切牙呈现典型的氟斑牙改变。低氟组(10mg/LNaF)大鼠60d和90d,均没有明显氟斑牙形成。在10,50和100mg/LNaF的剂量条件下染毒60d和90d,大鼠切牙细胞出现明显的DNA损伤,Olive尾距较对照组显著增高(P<0.05),而且在相同剂量条件下,染毒90d时的Olive尾距值比染毒60d时的Olive尾距值大(P<0.05)。在10,50和100mg/LNaF的剂量条件下染毒60d,大鼠切牙细胞增殖周期变化主要表现在,低氟组G2/M细胞显著减少,中氟组和高氟组的G2/M细胞明显增多。染毒90d,大鼠切牙细胞增殖周期却没有明显改变。结论:在氟中毒引起氟斑牙的过程中,大鼠切牙细胞增殖周期改变和DNA损伤发挥作用,但详尽机制仍需深入探讨。

Objective： To explore the role of cell proliferation and DNA damage in the formation of rat dental fluorosis induced by fluoride. Methods： Male SD rats were provided with distilled water to drink containing NaF at different doses （10, 50 and 100 mg/L respectively） for 60 or 90 days. The rat model for dental fluorosis was made. The cell cycle of proliferation was detected by flow cytometry in mandibular incisor ameloblasts and odontoblasts, and the DNA damage was also measured with single cell gel electrophoresis （or comet assay）. Results： NaF at the doses of 50 and 100 mg/L for 60 d and 90 d could increase serum fluoride concentration significantly, statistical analysis yielded close relationship between the dose of NaF in water and the level of NaF in serum, and the relative coefficient was 0.995 7 （P0.01） and 0.9880 （P0.05） respectively. NaF at the doses of 50 and 100 mg/L could cause dental fluorosis at rat mandibular incisor obviously, but 10 mg/L NaF failed to induce dental fluorosis for 60 and 90 days. Compared with control, olive tail moment of ameloblasts and odontoblasts at the doses of 10, 50, and 100 mg/L NaF were increased significantly （P0.05） for 60 and 90 days. At the same doses, olive tail moment of group for 90 days were more than those of 60 days obviously （P0.05）. After 60 days treatment, NaF reduced the cell number of G2/M phase in cell cycle at the dose of 10 mg/L, but increased the cell number of G2/M phase at the doses of 50 and 100 mg/L after 90 days, and the changes of cell cycle were not significant （P0.05） in rat ameloblasts and odontoblasts. Conclusion： It was suggested that ameloblast and odontoblast proliferation as well as their DNA damage could play roles in the formation of rat dental fluorosis induced by fluoride, but the mechanisms in detail needs to be studied further.