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

Abstract

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.