Association of bisphosphonate with bone loss and pain-related behavior in an adjuvant-induced osteoporosis model.

ABSTRACT

OBJECTIVES: Osteoporosis animal models are used extensively to determine the mechanisms of disease pathology and identify potential biological targets. The study aimed to establish a bone loss model, identify pain-related behavior in neighboring joints using an adjuvant-induced osteoporosis (AO) model, and examine the therapeutic effect of bisphosphonates (BP). METHODS: Complete Freund's adjuvant (CFA) was injected subcutaneously into the back of the right foot of 8-week-old female ddY mice. Subsequently, pain, arthritis, and bone density in the right knee were monitored over time. RESULTS: Pain evaluation using von Frey filaments showed a significantly exacerbated knee pain threshold compared to the control group (saline administration) at 7-day and 14-day intervals after CFA administration, and bone density during the same period also significantly declined. The AO model was created similarly; alendronate (ALN) 40 µg/kg was subcutaneously injected twice and vehicle once from 7 to 14 days after onset. In the ALN administration group on the 14th day, significant improvements in bone density, arthritis, and pain threshold around the knee were observed compared to the untreated group. CONCLUSIONS: ALN may contribute to pain improvement through the simultaneous effects of bone mass improvement and suppression of osteoporotic pain.