低钙联合高蛋白饲料对大鼠松质骨与代谢的影响和机制

Skeletal Effects in Cancellous Bone and Bone Metabolic Changes of Low Calcium and High Protein Dietary in female SDRats

目的 了解低钙联合高蛋白饲料对大鼠松质骨与代谢的影响 ,分析其机制。方法 3周龄清洁级健康雌性SD大鼠 2 0只 ,随机均分为 2组。实验组大鼠摄食为灭菌的低钙高蛋白饲料 ,对照组为标准饲料。试验时间 6月。处死大鼠取L3、L4和血清 ,检测骨源性碱性磷酸酶 (BALP)、骨钙素 (BGP)、尿吡啶酚 /肌酐 (PYD/Cr)和尿脱氧吡啶酚 /肌酐 (DPD/Cr) ,并用骨计量学和扫描电镜观察骨结构变化。结果 实验组骨源性碱性磷酸酶与对照组无显著差异 ,骨钙素、尿吡啶酚 /肌酐和尿脱氧吡啶酚 /肌酐升高明显。骨小梁面积减少 ,骨小梁厚度出现显著变窄 ,骨小梁结点末端比下降 ,骨小梁间距增宽但无统计学意义。扫描电镜示骨小梁纤细、稀疏 ,排列紊乱 ,骨髓腔扩大。结论 膳食中钙的摄入不足并且蛋白质含量过多会构成骨质疏松症的危险因素。

Purpose: To study the skeletal effects in cancellous bone and bone metabolic changes of low calcium and high protein dietary in rats. Methods: Twenty female SD rats aged 3 weeks old were randomly divided into the normal group and the experimental group. The experimental group was fed with low calcium(0. 025%) and high protein(27%) dietary and the normal group with basic food (calcium1%, protein 18%). After 6 months, the rats were killed. The serum and the third and the fourth lumbar vertebrae were collected. serum osteocalcin (BGP), serum bone specific alkaline phosphatase (BALP), unrinary pyridinoline/creatinine (PYD/Cr) and dexypyridinoline/creatinine (DPD/Cr) were examined. Bone morphometry and Scan Electronic Microscope(SEM) were used to investigated skeletal changes in cancellous bone. Results: The level of BALP in the experimental group did not increased compared with the normal group. Other biomedical parameters as BGP, PYD/Cr and DPD/Cr obviously increased. Trabecular area percent (Tb. Ar%) and Trabecular thickness (Tb. Th) of the experimental group significantly decreased. Ratio of Trabecular node and Trabecular terminal (NTR) also decreased. Trabecular separation (Tb. Sp) increased but had no significant difference. Scan electronic microscope (SEM) indicated that bone trabeculae became thinner, less and disorder. Medullary cavity of bone became larger. Conclusions: Combination of deficiency of calcium and excessive protein in the dietary is a risk factor of osteoporosis.