Effect of prednisone treatment for 30 and 90 days on bone metabolism in collagen-induced arthritis (CIA) rats

Glucocorticoids (GCs) are often prescribed to treat rheumatoid arthritis (RA) in the long term, but there is still controversy in the administration of GCs, mainly because of the adverse reactions such as osteoporosis. Numerous studies have demonstrated that osteoporosis could be induced by GCs in normal rats. However, few experiments have focused on whether osteoporosis could be induced or aggravated by GCs in collagen induced arthritis (CIA) rats. We have investigated bone changes in CIA rats treated with prednisone at 4.5 mg/kg/day for 30 and 90 days by bone histomorphometry, bone mineral density (BMD), micro-CT, biomechanical test, and enzyme-linked immunosorbant assay. We found that high bone turnover osteoporosis was shown in CIA rats. Prednisone treatment for 30 and 90 days improved articular structure and decelerated the degeneration of the femur in CIA rats, but did not improve BMD and bone biomechanics. We conclude that osteoporosis was not aggravated in CIA rats treated with prednisone for 30 and 90 days. On the contrary, prednisone treatment for 30 and 90 days could prevent bone loss of the femur in CIA rats. There was a negative effect on bone metabolism in CIA rats treated with prednisone for 90 days.