Effect of asprin administration for the treatment of osteoporosis in ovariectomized rat model

Objective: To explore the therapeutic effects of aspirin on postmenopausal osteoporosis and understand its action mechanism. Methods: Forty three-month-old female SD rats were randomly divided into 5 groups (n=8 each): sham group, OVX group and aspirin groups (A1, A2 & A3). The OVX and aspirin groups were ovariectomized (OVX). All rats underwent BMD (bone mineral density) scan at the time of OVX and 3 months after OVX. After the animal model of osteoporosis was established, aspirin groups were intragastrically administered at a dose of 8.93 mg · kg^-1 · d^-1 (A1), 26.79 mg · kg^-1 · d^-1 (A2) and 80.36 mg · kg^-1 · d^-1 (A3) daily in OVX rats. Three months later, the BMD and microarchitecture of vertebrae were measured by dual-energy X-ray absorptiometry and microtomograph. Alkaline phosphatase and osteocalcin were measured in peripheral blood. The trabecular architecture changes were observed by histomorphology. Axial compression tests were used to evaluate the mechanical properties of vertebral specimens and three-point bending tests used for femur shaft. Results: Three months after ovariectomy, BMD was significantly lower than preoperative. BMD in aspirin treated groups was significantly higher than that in OVX group. Alkaline phosphatase in peripheral blood decreased significantly in aspirin groups than those in OVX, but osteocalcin had no significant difference between aspirin and OVX groups. The microtomograph reconstruction analysis also showed that the trabecular thickness, trabecular number and BMD increased significantly in aspirin groups than those in OVX. And there was no significant difference between A3 and sham groups. The results of biomechanical test showed that the maximum compression load of lumbar spine and three-point bending load of femur shaft were significantly higher in aspirin groups than those in OVX group. Conclusion: Aspirin can promote trabecular bone remodeling, improve three-dimensional structure of trabecular bone and increase bone density of cancellous in osteoporotic rats by stimulating bone formation. It may become a new drug for the treatment of osteoporosis.