The development of bone microstructure, metabolism and biomechanics in lumbar vertebra under short-term...

Abstracts Objective: This study investigated the characteristics of bone microstructure, metabolism, and biomechanics in rat's lumbar vertebra undergoing short-term glucocorticoid administration. Methods: Forty 4-month-old female Sprague-Dawley rats were treated with either vehicle (Cont) or prednisone acetate (Pre) at 3.5 mg/kg/day, respectively for periods of 7 days and 21 days. The lumbar vertebras were processed for MicroCT scan, histomorphometry analysis, mechanical compression test, in addition to Dual-Energy X-ray absorptiometry scan, respectively. Results: The connective density (Conn. D) along with trabecular connection nodes decreased while trabecular termini increased in Pre at day 21 when compared to Cont at day 21 as well as Pre at day 0. The mineralizing surface (MS/BS), mineral apposition rate (MAR), bone formation rate (BFR), osteoblast surfaces (Ob.S/BS) were lower in Pre at day 21 than that in Cont at day 21, Pre at day 0 and Pre at day 7. Only the bending stiffness of compression test decreased in Pre group at day 21 compared to age-matched control. Conclusion: The results suggested that excess prednisone significantly inhibited bone formation and slightly depressed bone resorption in the lumbar vertebra of intact rats for the duration of 21 days. Accordingly, the trabecular spatial microstructure made an adjustment yet failed to maintain the anti-compression mechanical property.