Histological assessment of zoledronic acid (Aclasta) in protection against induced osteoporosis in female albino rats

Introduction: Osteoporosis is a major health problem that leads to morbidity and mortality.Aim: This study was designed to assess the beneficial effect of zoledronic acid in the protection against experimentally induced osteoporosis and to test the optimal dose that would result in this effect.Materials and methods: Twenty-four female albino rats were divided into four groups (N=6). Group I (control group) were sham operated. Group II (ovariectomy group) were subjected to removal of both ovaries to induce artificial menopause. Group III underwent ovariectomy, followed by administration of zoledronic acid (a single low dose). Group IV was similar to group III except that they were injected with a single high dose of zoledronic acid. After 16 weeks, the femurs of the animals were prepared for both light (hematoxylin and eosin and Masson s trichrome stains) and scanning electron microscopic examinations. Cortical bone thickness and area percentage of collagen were assessed using the image analyzer, in addition to counting the numbers of both osteoclasts and osteoblasts.Results: Group II showed significant reduction of cortical bone thickness with multiple cavity formation. There was also significant reduction in the number of osteoblasts and matrix collagen, as well as a significant increase in the number of osteoclasts, compared with group I. Scanning electron microscopic examination confirmed these results. Group III showed an improvement in these previous parameters; however, the improvement was marked in group IV.Conclusion: Zoledronic acid is effective in protection against induced osteoporosis, especially when used in a high cumulative dose