Objective: To study the pharmaceutical effects of 1 alpha(OH)D3 on trabecular and cortical bone in ovariectomized (OVX) rats.
Methods: 41 female Wistar rats of six months old were randomly divided into 5 groups: (1) Baseline control; (2) Sham control; (3) 6 weeks after OVX (OVXb); (4) 14 weeks after OVX (OVXe); (5) OVX + 0.1 microgram/(kg.d) 1 alpha(OH)D3 (O + VD), treatment started 6 weeks after OVX and lasted 8 weeks. Histomorphometry analysis of tibia, peripheral quantitative computed tomography (pQCT) scanning of femur, bone biomechanical test and serum and urinary biochemical parameters were determined.
Results: The levels of bone turnover indexes increased in OVX rats, OVX also resulted in reducing of trabecular, bone mass and biomechanical properties. The ratio of urinary deoxypyridinoline crosslink/creatinine was decreased by 67.0% in O + VD group compared with OVXe group 67.0% [(43.50 +/- 11.20) nmol.L-1/mmol.L-1 vs(131.80 +/- 14.90) nmol.L-1/mmol.L-1, P < 0.01]. Percent trabecular area (Cn-BV/TV) was increased by 89.8% in O + VD group compared with OVXe group (11.03 +/- 0.73 vs 5.81 +/- 1.29, P < 0.05). Trabecular bone mineral content and density were increased by 77.3% and 91.3% compared with OVXe respectively (P < 0.05). Although cancellous maximal load and stiffness increased in O + VD group, but no statistical significance. 1 alpha(OH)D3 also enhanced polar moment of inertia (PMI) and maximal load of cortical bone in femur compared with OVXe (23.70 +/- 1.63 vs 18.23 +/- 1.41, P < 0.01 and 171.69 +/- 9.92 vs 147.58 +/- 11.29, P < 0.05 respectively).
Conclusion: 1 alpha(OH)D3 inhibited the higher bone turnover induced by OVX, increased trabecular bone in proximal tibia and bone mass in distal femur. 1 alpha(OH)D3 also improved the mechanical properties of cortical bone in femur.