Serum osteocalcin levels and bone mineral density in ovariectomized rats

Objective: This study aims to investigate ovariectomy effect on serum osteocalcin levels and bone mineral density in rats. Methods: Forty five female Sprague Dawley rats were divided into 3 groups (n = 15 rats per group): sham-operated control, Ovariectomized, and Ovariectomized plus estrogen. After 3 months of experiment, rats were killed by decapitation after a 12 hour fast, obtained serum from rats' blood sample was kept at –80°C. For all groups of rats, serum osteocalcin levels were measured by ELISA. The rats' left femoral bone mineral density was measured by dual energy X-ray absorptiometry. Weights and lengths of the left femur were measured with electronic balance and Vernier caliper respectively. Results: This study revealed an increase in serum osteocalcin levels in ovariectomized rats and in ovariectomized plus estrogen rats, alongside decrease in left distal femur bone mineral density in both groups was observed when compared to the control. The mean values of both serum osteocalcin and bone mineral density between the ovariectomized rats and the control were statistically significant. Estrogen administration in ovariectomized rats showed no significant changes in both serum osteocalcin levels and bone mineral density. Conclusion: This study concludes that estrogen-deficiency by ovariectomy induces an increase in bone turnover with higher serum osteocalcin levels in ovariectomized rats and that the combination of serum osteocalcin levels and bone mineral density measurement may be a better predictor of the fracture risk.