Effects of Teriparatide and Aerobic Exercise on Lumbar Spine Microstructure in Ovariectomized and Tail-Suspended Rats

Abstract

Osteoporosis is an increasingly prevalent malady of the elderly that is associated with bone fragility and increased risk of fractures. Osteoporosis treatments focus on restoring bone strength and quality. Teriparatide (TPTD) is a therapeutic agent that has been shown to increase bone strength by improving the volume and connectivity of trabecular bone. Exercise is also known to have pro-osteogenic effects. Here we used a rat model of severe osteoporosis (ovariectomized and tail-suspension) to evaluate the effects of TPTD, exercise and a combination of TPTD and exercise on the microstructure of trabecular bone. TPTD mono-therapy and TPTD combined with exercise treatment significantly increased bone mineral density (BMD) in the whole body. Micro-computed tomography analysis revealed that a combination of exercise and TPTD treatment significantly decreased bone surface to volume and trabecular separation compared with those of the control and exercise groups. Node-strut analysis indicated that exercise or TPTD alone did not affect trabecular bone connectivity. However, the combination of exercise and TPTD treatment significantly decreased measures of trabecular bone connectivity (node number) that are consistent with a transition from rod-like to plate-like of trabecular bone microstructures. The combination treatment with exercise and TPTD improved microstructure of trabecular bone in the OVX and tail-suspended rats. These results indicate that combining exercise with TPTD represents a viable means to improve cancellous bone strength in osteoporosis populations.