Effect of short-term dietary calcium deficiency on biomechanical properties of femurs in ovariectomized rats

Objective To study the effect of short-term dietary calcium deficiency on the biomechanical properties of femurs in ovariectomized rats.||Methods Sham operated and OVX rats were divided into four groups based on the dietary calcium level 5 weeks after the operation:Sham+NCD(normal calcium diet) (SN); Sham+LCD (low calcium diet) (SL); OVX+NCD (ON); OVX+LCD (OL). Another group (C) was taken as normal control.Two weeks later, urine specimens were collected and blood was taken from the abdominal aorta.Femurs were collected and stored at -20℃ for three-point bending test in the diaphysis. Protein expression in proximal femur was detected by Western blot.||Results Two-way ANOVA anslysis showed that the levels of serum ALP (P<0.001) and urine DPD (P<0.01) were significantly elevated after OVX, and femoral elastic modulus (P<0.05) and toughness (P<0.05) was reduced. Significant decrease of biomechanical markers, stiffness, energy absorption and toughness was observed in OL group, but not in those with short-term low calcium intake only. Vitamin D receptor (VDR) expression of proximal femur in LCD group was higher than that in NCD group.||Conclusions Active bone turnover is observed in ovariectomized rats which can be aggravated by short-term dietary calcium deficiency. Calcium restriction has certain influence on bone mineral metabolism.