EFFECT OF MILK BASIC PROTEIN ON BONE METABOLISM IN NORMAL AND OVARIECTOMIZED RATS / 营养学报

ABSTRACT

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.