不同治疗时间脉冲电磁场对去卵巢大鼠股骨生物力学性能的影响

Effect of Pulsed Electromagnetic Fields on Biomechanical Properties of Femur in Ovariectomized Rats

目的通过采用不同治疗时间脉冲电磁场(PEMFs)干预去卵巢大鼠骨质疏松模型,观察各组大鼠的股骨生物力学性能的变化,以探索PEMFs治疗骨质疏松的最适治疗时间。方法将雌性3月龄SD大鼠50只随机分为5组:SHAM组、OVX0组、OVXⅠ组、OVXⅡ组、OVXⅢ组,每组10只。各OVX组均按文献方法切除双侧卵巢造模,SHAM组仅开腹不切除卵巢。OVXⅠ、OVXⅡ和OVXⅢ3组大鼠每天在强度为3.8 mT,频率为8 Hz的磁场环境中分别照射20、40、60 min,共30 d。SHAM组和OVX0组不干预。各组动物均在实验完成后股动脉放血处死,取右侧股骨作生物力学性能测定。结果OVX0组大鼠的股骨结构力学指标(包括最大位移、最大载荷及最大能量吸收,下同)和材料力学指标(包括最大应力、最大应变及弹性模量,下同)低于其它4组大鼠(P<0.05或P<0.01),但SHAM组、OVXⅠ组、OVXⅡ组及OVXⅢ组4组大鼠的股骨生物力学指标之间的差异无统计学意义(P>0.05)。结论采用磁场强度(3.8 mT)和脉冲频率(8 Hz)PEMFs,每天治疗20～60 min,可阻止去卵巢大鼠的股骨生物力学性能下降,使其接近正常的水平,其骨生物力学性能的维持效果相同。

Objective To test the effect of pulsed electromagnetic fields（PEMFs） with different length of treatment on the biomechanical properties of femurs in ovariectomized rats.Methods Fifty female SD rats were randomly divided into five groups： ① SHAM control（no PEMFs treatment）,② OVX0 control（no PEMFs treatment）,③ OVXⅠ（PEMFs treatment at 8 Hz frequency with 3.8 mT intensity,20 min daily for 30 days）,④ OVXⅡ（PEMFs treatment at 8 Hz frequency with 3.8 mT intensity,40 min daily for 30 days）,and ⑤ OVXⅢ（PEMFs treatment at 8 Hz frequency with 3.8 mT intensity,60 min daily for 30 days）.All of the rats were subject to bilateral overiectomy except those in the SHAM control group.The biomechanical properties of the femurs were assessed at the end of the PEMFs treatment.Results The rats in the OVX0 control group had significantly lower values in the biomechanical properties than the rats in the other four groups（P〈0.05 or P〈0.01）.The rats treated with PEMFs showed no significant differences in the biomechanical properties compared with the sham controls（P〉0.05）.Conclusion PEMFs therapy at 8 Hz and 3.8 mT magnetic intensity for 20 to 60 min everyday prevents decline in biomechanical properties of femurs in ovariectomized rat.