The Effect of Systemic Delivery of Bisphosphonates on Trabecular and Cortical Bone Mass of Ovariectomized Rats

Bisphosphonates are one of the most important drug families, which inhibit osteoclast-mediated bone loss due to osteoporosis and other disorders. However, the impact of different members of this family of drugs on the various cortical and trabecular bone mineral density wasn’t investigated. In this study the therapeutic effects of bisphosphonates in Ovariectomized (OVX) female rats was assessed, for eight weeks, and these effects were compared on trabecular and cortical bones. Thirty adult female rats (225 + 25 g) were divided to five equal groups [Sham, the untreated OVX rats (negative control), and the OVX rats treated with zoledronic acid, alendronate, and risedronate]. The effectiveness of these treatments after eight weeks was comprehensively evaluated by in vivo and in vitro analysis. Systemic delivery of zoledronic acid, alendronate, and risedronate had statistically significant effects on serum parameters in comparison to the untreated OVX animals. Moreover, administration of zoledronic acid, alendronate, and risedronate increased expression of osteogenic genes (OCN, ALP, and Col1), bone mineral density (BMD), and biomechanical performance of the OVX-induced osteoporotic bones in comparison with the untreated OVX rats (P < 0.05). However, different analyses showed that trabecular BMD significantly increased in zoledronic acid- and risedronate-treated animals in comparison to those of the alendronate-treated group (P < 0.05). It was concluded that zoledronic acid, alendronate, and risedronate sufficiently improved OVX-induced osteopenia. Moreover, it was found out that zoledronic acid and risedronate considerably improved the regeneration of trabecular bones in comparison to the alendronate.