早期干预对脊髓损伤大鼠骨密度的影响

目的：建立脊髓损伤(SCI)动物模型，探讨在SCI后早期应用阿仑膦酸钠(ALN)和，或脉冲电磁场(PEMFs)对SCI大鼠骨密度(BMD)的影响。方法：将62只3月龄健康雌性SD大鼠随机分为假手术(Sham)组、SCI组、SCI ALN组、SCI PEMFs组、SCI PEMFs ALN组，Sham组仅行椎板切除术，其余4组行T10椎体水平脊髓完全横向切断术。脊髓横断大鼠于术后1周开始应用ALN和，或PEMFs，ALN每次0．25mg/kg腹腔注射，每周3次，共7周；PEMFs 30min／d，共7周。所有动物于术后8周时取材，检测股骨BMD值。结果：3月龄健康雌性SD大鼠脊髓完全横断术后8周时股骨BMD显减低；PEMFs早期应用可使股骨整体、股骨中段及下端BMD显增高：ALN早期应用可使股骨整体、股骨中段及股骨上下端BMD显增高；在本实验条件下ALN作用比PEMFs更强、更全面：ALN及：PEMFs早期联合应用比二单独应用时在BMD方面表现出更好的改善趋势，但析因分析表明二早期联合应用的协同效应不显。结论：3月龄雌性健康SD大鼠脊髓完全横断术后8周时股骨已发生显的骨量丢失：ALN及PEMFs早期应用可抑制SCI后骨量丢失，其中ALN的作用比PEMFs更强。

Effect of early intervention on bone mineral density of the femurs in spinal cord injured rats

Objective: To establish an animal model of spinal cord injury(SCI), and to explore the effect of early administration of alendronate(ALN) and pulsed electromagnetic fields(PEMFs) on bone mineral density (BMD). Method:62 healthy 3-month-old female SD rats were randomly allocated into 5 groups: sham group, SCI group, SCI+ALN group, SCI+PEMFs group,SCI+PEMFs+ALN group. Rat in the sham group underwent laminectomy, while rats in the other 4 groups underwent complete spinal cord transection at the level of the tenth thoracic vertebra, and was treated with ALN and/or PEMFs 1 week after SCI. ALN was injected intraperitoneally three times a week, 0.25mg/kg body weight each time, for 7 weeks. PEMFs treatment was given 30 min/d, for 7 weeks. All rats were sacrificed 8 weeks after operation. BMD of femurs was measured in order to observe the changes after SCI and the effect of ALN and PEMFs on BMD and also to explore whether there was any interaction effect between ALN and PEMFs. Result:For healthy 3-month-old female SD rats, the BMD of femurs of spinal cord transected rats at 8 weeks post-operation was significantly lower than that of rats in the sham group. After early treatment of PEMFs, the BMD of total femurs and the middle or lower part of femurs was significantly increased than that of rats in the SCI group. After early administration of ALN, the BMD of total femurs and the 3 parts of femurs was significantly increased than that of rats in the SCI group. In the experimental conditions of our study, ALN had stronger effect than PEMFs. Although the outcome of combined treatments of ALN and PEMFs had appeared to be well than that of single treatment, there was no interaction effect between ALN and PEMFs. Conclusion: The animal experimental study demonstrates that for healthy 3-month-old female SD rats, the BMD of femurs has changed significantly 8 weeks after spinal cord transection. The early treatment of ALN and PEMFs can reduce the loss of bone. ALN has stronger effect than PEMFs, and there is no synergistic effect between ALN and PEMFs.