Effects of Alendronate on Bone Mineral Density and Nociceptive Pain in Chronic Pain Model Rats

Objective : Alendronate (ALN) is used to treat postmenopausal osteoporosis, and it is also considered to have analgesic effect. However, the effects of ALN on hyperalgesia in the postmenopausal osteoporosis and chronic pain model are still unclear. In this study, the effects of ALN on nociceptive pain, as well as bone mineral density (BMD), were evaluated by a chronic constriction injury (CCI) model in ovariectomized (OVX) rats. Methods : Four-week-old, Wistar rats underwent OVX, and then the left sciatic nerve was ligated to make a CCI, at 8 weeks of age. ALN (0.15 mg/kg/week) or its vehicle was administered for 2 weeks starting on the 0th day of CCI. Behavioral evaluations with the von Frey test and the hot plate test were performed on days 0 (8 weeks old) and 14 (10 weeks old). After evaluation, bilateral femora were harvested for BMD measurement. Results : Two weeks of treatment with ALN showed no significant improvement of mechanical and thermal hypersensitivity in CCI limbs. ALN treatment significantly increased femoral BMD in the sham and CCI limbs compared with vehicle treatment (p < 0.01) at 10 weeks old. Conclusion : Two weeks of treatment with ALN improved BMD in CCI limbs in OVX rats, but mechanical and thermal hypersensitivity were not improved by ALN treatment.