氟对大鼠成骨细胞SPARC mRNA及其蛋白表达的影响

目的观察慢性氟中毒时大鼠成骨细胞中成骨相关蛋白SPARC mRNA及其蛋白表达水平的影响,并探讨SPARC在氟骨症发病机制中的可能作用。方法 36只健康SD大鼠按体重、性别随机分3组,对照组自由饮用自来水(氟<1mg/L),低、高氟组分别饮用添加氟化钠5、50mg/L的自来水。饲养8个月后,股动脉放血处死大鼠,用氟离子选择电极法测各组尿氟、骨氟含量。HE染色后光镜下观察股骨下段骨组织的病理学改变及形态计量学测量。免疫组织化学和原位杂交技术检测成骨细胞中SPARC蛋白及其mRNA的表达水平。结果低氟组大鼠尿氟、骨氟含量(6.09±0.56)mg/L、(12.65±3.07)μg/g]显著高于对照组(1.36±0.51)mg/L、0.67±0.16)μg/g],差异有统计学意义(P均<0.05),高氟组(7.69±0.64)mg/L、(26.53±5.88)μg/g]较低氟组升高,差异有统计学意义(P均<0.05)。染氟组大鼠股骨下段呈骨质硬化表现。低氟组大鼠SPARC蛋白及其mRNA表达水平(125.24±1.91、100.90±1.13)明显高于对照组(109.70±1.70、88.03±1.26),差异有统计学意义(P均<0.05),高氟组(139.47±1.03、119.22±1.23)较低氟组升高,差异有统计学意义(P均<0.05)。结论过量氟可通过上调大鼠成骨细胞中SPARC蛋白及其mRNA表达水平来调节成骨细胞的增殖、分化、成熟等过程,使骨形成增加,表现为骨硬化型。

Effects of chronic fluorosis on SPARC mRNA and its gene expression in osteoblasts of bone tissue inrats

Objective To study the effect of chronic fluorosis on SPARC mRNA and its gene expression in osteoblasts in bone tissue of rats,and to explore the potential role of SPARC in the pathogenic mechanism of fluorosis.Methods Thirty-six SD rats were randomly divided into three groups based on the gender and body weight,in which rats were fed with pure tap water（control group）or water containing NaF either 5mg/L or 50mg/L（low NaF and high NaF group）for 8 months.Rats were sacrificed after eight months,the fluoride concentrations in urine and bone tissue were determined by fluoride selective electrode method.The bone tissue paraffin sections were stained by hematoxy-eosin（HE）and pathological morphometry was observed under optical microscope.The immunohistochemistry（IHC）and in-situ hybridization（ISH）were used to detect the protein and mRNA levels of SPARC in osteoblasts of bone tissue of rat.Results The fluoride concentration in urine and bone samples in rats in high NaF group were both much higher than those in low NaFgroup（7.69±0.64 vs 6.09±0.56,26.53±5.88 vs 12.65±3.07）（P0.05）,which were also significantly higher compared to the control group（6.09±0.56 vs 1.36±0.51;12.65±3.07 vs 0.67±0.16）（P0.05）.The pathological examination showed that bone trabecular were formed and broadened in NaF-group,Meanwhile,the protein expression and mRNA of SPARC in low NaF group（125.24±1.91 and 100.90±1.13）were significantly higher than that in control group（109.70±1.70 and 88.03±1.26）（P0.05）,and these numbers were even higher in high NaF group（139.47±1.03 and 119.22±1.23）.Conclusions Excessive fluoridemight up-regulate the expression of SPARC gene and mRNA which in turn enhances the proliferation,differentiation and maturity of osteoblasts in bone tissue,and increases the formation of bone tissue and bone sclerosis.