Effect of Calcitonin Treatment on Bone Quality and Collagen Structure in Ovariectomized Rats

The aim of this study was to investigate the effect of calcitonin on cortical bone quality and collagen structure at ovariectomized rat model. Forty five Sprague-Dawley female rats were assigned randomly to control group (CON, n=15) ovariectomized group receiving saline only (OVX, n=15), and ovariectomized group receiving salmon calcitonin (i.p.) (OVX-CT, n=15). Thirty rats were anaesthetized with ketamine and underwent bilateral ovariectomy via ventral incision. Ten weeks after ovariectomy, OVX-CT rats were treated with salmon calcitonin at the dose of 2 IU/kg body weight once per week for 12 weeks. BMD of the cortical femur was measured using dual energy X-ray absorptiometry, cross sectional area of the cortical femur was measured by computerized tomography and the length of the cortical femur was measured with a digital caliper. Tensile test was performed to measure stress, strain and toughness of cortical femur. In the OVX-CT group; stress, strain and toughness were not different than OVX group and significantly lower (p<0.05) than those of control group. Regular collagen fiber organization was observed in the CON group, whereas the parallel packing of fibrils was completely replaced by a random arrangement in OVX and OVX-CT rats. 12 weeks calcitonin treatment leads to significant increase of the BMD without any change in bone biomechanical parameters and collagen ultrastructure in ovariectomized rats.