Intermittent cyclical etidronate treatment maintains the mass, structure and the mechanical property of bone in ovariectomized rats

Abstract

We examined the mechanical properties of rat bones treated with etidronate intermittent cyclic treatment (etidronate-ICT). Fifty Fisher rats, 7 months of age, underwent ovariectomy (OVX; n = 40) or sham operation (n = 10). The OVX rats were assigned to 4 groups injected with etidronate at the respective dose of 0, 2, 4, or 8 mg/kg of body weight (bw) 5 days each week for 2 weeks, followed by a 10-week period of no treatment. This regimen was repeated for 48 weeks. At the end of the treatment period, the ultimate bending strength and structural stiffness of the femoral midshaft in the OVX-alone group were not reduced compared with the values of the sham group, while those in the etidronate-treated groups were significantly larger than the values of the OVX group. The compressive stiffness and strength of the vertebral bodies specimens prepared from L3 and L5 vertebrae were markedly decreased in the OVX group compared with those in the sham group, but the values in the etidronate-treated groups were maintained at the same levels as those in the sham group. Mechanical properties at the tissue level, such as elastic modulus and material strength of the femoral cortex, were increased in etidronate-treated groups compared with the OVX group. The flexural modulus was also increased. The compressive elastic modulus of vertebral body in treated groups was preserved at the same level as that in the sham group. These results clearly demonstrate that in ovariectomized rats long-term etidronate intermittent cyclic treatment preserves the mechanical properties both at the whole bone and the tissue level.

Characterization of the physical and mechanical properties of femoral bone defects filled with polyanionic collagen scaffolds in ovariectomized rats

“…Katsumata et al 23 and Shen et al 3 observed a decrease of bone mineral content and density in the femur of ovariectomized rats compared to the intact group, but there was no difference between groups in terms of fracture resistance or rigidity. Wang et al 25 evaluated the influence of osteoporosis on the middle and late periods of tibia fracture healing in ovariectomized rats, analyzing histomorphological changes, bone mineral density and biomechanical properties.…”

“…However, an increase in bone strength and rigidity does not necessarily indicate improvement in the biomechanical properties of bone tissue 23 . We therefore used a three-point bending biomechanical test.…”

Alfacalcidol Inhibits Bone Resorption and Stimulates Formation in an Ovariectomized Rat Model of Osteoporosis: Distinct Actions from Estrogen

“…During data analysis, the femur was divided into 20 equal segments along its major axis. The mean values of BMD for the six most proximal scanned areas (1)(2)(3)(4)(5)(6), those for the next eight scanned areas (7)(8)(9)(10)(11)(12)(13)(14), and those for the six most distal areas (15)(16)(17)(18)(19)(20) were…”

Hypothalamic Suppression Decreases Bone Strength Before and After Puberty in a Rat Model

“…The relative rates of resorption and formation on the periosteal and endocortical surfaces would affect the cortical width, total area, and moment of inertia, and thus bone strength [40]. An increase in periosteal bone formation rate has resulted in increased bone strength due to an increased moment of inertia [19–21, 41]. However, in prepubescent animals that receive GnRH-a injections, the increased periosteal formation did not rescue bone strength [27].…”

“…Furthermore, increased femoral periosteal circumference and moments of inertia have been reported after ovariectomy [19, 20]. As a result, mechanical strength after ovariectomy may not decrease and has actually been reported to increase in some studies [19–21]. These data support the hypothesis that suppressed estradiol should result in stronger bone; however, an animal model of delayed puberty (suppressed estrogen levels) has reported short-term decreases in peak moment and stiffness without changes in total area or bone area [22].…”