effects of calcium and vitamin d supplementation on bone quality in an ovariectomized rat model

Abstract Introduction: Many osteopenic patients or patients with osteoporosis are treated only with calcium and vitamin D (vit D) as a preventive or therapeutic regimen. All the clinical trials about the use of osteoporosis treatments administered calcium and vit D to both control and intervention groups. Aim of the study: To determine if treatment with calcium and vit D is useful in the treatment of osteoporosis. With this purpose we study the effects on bone quality produced by long-term treatment with calcium and vit D in ovariectomized rats. Methods: Forty-five 6-month-old female Wistar rats were grouped as follows: SHAM (n=15), simulated intervention; OVX (n=15), ovariectomized; and OVX+(Ca+vit D) (n=15), ovariectomized treated with calcium and vit D (10 mg of calcium and 6.7 IU of vit D/kg/day by oral gavage). The rats were sacrificed 8 months after treatment. We measured femoral (F) and lumbar (L) Bone Mineral Density (BMD), biochemical markers of bone turnover, and trabecular microstructure, irregular structures through fractal dimension analysis in 2D (D2D) and 3D (D3D) and biomechanical testing by finite elements analysis. Results: FBMD and LBMD decreased in OVX rats, with no changes observed in treated rats. Ovariectomy produced an increase in osteocalcin values and carboxyterminal telopeptide/tartrate resistant acid phosphatase, producing no differences in aminoterminal propeptide of procollagen I; These variations did not change after treatment. Ovariectomy produced a decrease in bone microstructural parameters maintained under treatment with calcium and vitamin D. D2D decreased significantly in the OVX group, while no changes were evidenced on D3D; no variations were seen after treatment with calcium and vit D. The apparent elastic modulus in the x, y, and z direction was significantly decreased in the OVX group, with no differences after treatment. Ovariectomy significantly increased the weight of the rats. Treatment with calcium and vit D prevented this increase. Conclusion: Long-term treatment with calcium and vit D did not revert alterations in bone quality caused by ovariectomy. Keywords Calcium; Ovariectomy; Vitamin D