牛乳碱性蛋白对正常和去卵巢大鼠骨代谢的影响

目的探讨牛乳碱性蛋白(MBP)对正常大鼠和去卵巢大鼠骨代谢的影响。方法将60只去除卵巢雌性SD大鼠随机分为假手术、去卵巢对照以及去卵巢低、中、高剂量5组;将另外44只正常雌性SD大鼠随机分为正常对照、正常低、中、高剂量4组。分别采用10、20、30mg/kgbwMBP给大鼠连续灌胃90d,检测股骨近心端、中段和远心端骨密度,同时检测股骨中Ca、Mg、P等矿物元素含量。结果正常低剂量组大鼠股骨远心端骨密度显著高于正常对照组;而各剂量MBP对去卵巢大鼠的骨密度无显著作用;正常各组之间以及去卵巢组之间比较,骨矿物质含量虽无统计学差异,但可以观察到其水平上的上升趋势。结论10mg/kg.bw的MBP能提高正常生理状态下的峰值骨密度,以股骨远心端效果最好,但未见MBP对去卵巢大鼠骨密度的影响。MBP除影响骨骼中矿物元素含量外,还可能通过其他方式作用于骨代谢。

EFFECT OF MILK BASIC PROTEIN ON BONE METABOLISM IN NORMAL AND OVARIECTOMIZED RATS

Objective To investigate the effect of milk basic protein (MBP) on bone metabolism in normal and ovariectomized (Ovx) rats. Method Forty-eight female Sprague-Dawley rats were ovariectomized and another 12 rats received sham operation (Sham). After 10 d recovery period, the Ovx rats were randomly divided into 4 groups: control, low-dose, medium-dose, and high-dose MBP group. Another 44 normal female rats without ovariectomy were also divided into 4 groups as above. The MBP dosages for each group were respectively 0, 10, 20, 30 mg/kg bw. All rats were i.g. administered for 90 d. Bone mineral density (BMD) of the femur (at proximal end, middle of diaphysis, and distal end) was measured by dual-energy X-ray absorptiometry in vivo. The amounts of calcium, magnesium and phosphorus were analyzed by ICP-AES. Results BMD at distal end of femur was significantly higher in normal low-dose group than in normal control group while no significant effect was observed in Ovx MBP groups. As for the amounts of calcium, magnesium and phosphorus, there were no significant differences among normal experimental groups and also among Ovx experimental groups. However, some variations in the level of those minerals were observed. Conclusion MBP at 10 mg/kg bw significantly elevated BMD at femoral distal end in normal rats, while no similar effect was observed in Ovx rats. Besides its influence on bone minerals, there may be another mechanism involved in its effect on bone metabolism.