长期接受不同饮食磷水平的慢性肾衰竭大鼠骨组织形态学特征改变

Effects of long-term various levels of dietary phosphorus feeding on bone morphology in the rats with chronic renal failure

目的探讨调节饮食磷水平对肾性骨病大鼠骨代谢的影响。方法选择24只SD大鼠,分为模型组(CRF组)、高磷饮食组(CRF-HP组)、低磷饮食组(CRF-LP组)、假手术组(Sham组),每组各6只。5/6肾切除法制备慢性肾衰竭模型。前3组成模3周后,分别接受正常磷(磷0.9%,钙1.2%)、高磷(磷1.2%,钙1.6%)、低磷低钙(磷0.2%,钙0.5%)饮食。Sham组接受正常磷饮食。27周取血测肌酐后,处死各组大鼠,取股骨,固定包埋,Giemsa、VonKossa染色计算骨小梁体积(TBV)、成骨细胞指数(OBI)、破骨细胞指数(OCI)、类骨质体积(OV/TV),并观察皮质骨形态改变;四环素双标记法检测骨形成率(MAR)。结果 CRF-HP组、CRF-LP组、CRF-模型组、Sham组大鼠分别存活6只、3只、5只、6只。CRF模型组大鼠TBV、OBI、OCI、OV/TV较Sham组大鼠明显增加(14.4±5.2vs.20.2±6.3,P<0.05;141.0±53.3vs.80.0±24.1,P<0.05;9.4±3.0vs.4.5±1.3,P<0.01;1.14±0.02vs.0.21±0.03,P<0.01),MAR较Sham组大鼠也有增加(0.8±0.2vs.2.1±0.4,P<0.01)。CRF-HP组以上改变较模型组更为明显(均P<0.05),但皮质骨吸收孔增加。CRF-LP组大鼠TBV、OBI、OCI、MAR较模型组减少,但OV/TV有所增加。结论长期接受高磷饮食的慢性肾衰竭大鼠骨转化率明显增加,松质骨量增加,但皮质骨量减少;长期接受低磷低钙饮食虽然能纠正慢性肾衰竭大鼠骨转化率的升高,但松质骨量减少,类骨质增加。

Objective To observe the bone morphology changes in chronic renal failure rats that were fed with different levels of dietary phosphorus for long time. Methods Twenty four S-D rats were divided into high-phosphorus diet （HP group）,low phosphorus diet （LP group）,model group,sham operation group （sham group） （n=6）. 5/6 nephrectomy model of chronic renal failure were prepared. After 3 weeks,the first 3 groups received high phosphorus （P 1.2%,calcium 1.6%）,low phosphorus （P 0.2%,calcium 0.5%） and normal phosphorus （P 0.9%,1.2% calcium） diet. The sham group received normal phosphorus diet,too. After the serum creatinine levels were tested at week 27,the rats were sacrificed,and their femur were removed,fixed-embedded,and examined with Giemsa,Von Kossa staining. Trabecular bone volume calculation （TBV）,osteoblast index （OBI）,the osteoclast index （OCI ） and osteoid volume （OV / TV） were measured,and the morphological changes of cortical bone were observed. By tetracycline double labeling technique,bone formation rate （MAR） was analyzed. Results The survival number in HP,LP,model group,and Sham group were 6,3,5,6 respectively. In the model group,TBV,OBI,OCI,OV / TV were significantly increased compared with those in the sham group （20.2±6.3 vs. 14.4±5.2,P 0.05; 141.0±53.3 vs. 80.0±24.1,P 0.05; 9.4±3.0 vs. 4.5±1.3,P 0.01; 1.14±0.02 vs. 0.21±0.03,P 0.01）,and so were MAR （2.1±0.4 vs. 0.8±0.2,P 0.01）. These changes in high-dose HP group were even more evident than those in the model group （all P 0.05）,but the cortical bone porosity was increased. TBV,OCI,MAR in LP rats were significantly lower than those in the model group,but OV/TV increased. Conclusion long-term high-phosphorus diet in rats with chronic renal failure can significantly increase bone turnover rate,increase cancellous bone and cortical bone loss. Although long-term low phosphorus diet can effectively correct the increased rate of bone turnover in chronic renal failure rats,it may contributes to reduced cancellous bone mass and increased osteoid volume.