低频脉冲电磁场对青年大鼠峰值骨量的影响研究

Effect of low frequency pulsed electromagnetic field on peak bone mass in young rats

目的:比较1 h和1.5 h下低频脉冲电磁场对生长期大鼠骨质量的影响。方法 :选取4周龄30只雄性SPF级SD大鼠,体重(115.8±1.5) g,采用随机数字表法将大鼠分为对照组、1 h组和1.5 h组,每组10只。对照组大鼠在电磁场装置中每天静置1.5 h,1 h组和1.5 h组均使用50 Hz 0.6 mT强度脉冲电磁场每天分别干预大鼠1 h和1.5 h。每2周称量大鼠体重,检测大鼠全身骨密度值,6周后处死大鼠检测右侧股骨和腰椎离体骨密度和生物力学值。ELISA法测定血清骨钙素(osteocalcin,OC)和抗酒石酸酸性磷酸酶5b(tartrate-resistant acid phosphatase 5b,TRACP 5b)浓度。品红-苦味酸染色后观察其右侧胫骨微组织结构,IPP 6.0软件对骨小梁相关参数进行分析。结果:各组不同时间点大鼠体重和脏器指数比较差异无统计学意义。骨密度结果显示:与对照组相比,6周时1.5 h组的全身骨密度、股骨和椎骨离体骨密度显著增加;且1.5 h组股骨和椎骨骨密度高于1 h组。股骨三点弯曲和椎骨压缩试验结果显示:与对照组相比,1.5 h组股骨和椎骨最大载荷值明显增加,且1.5 h组股骨最大载荷值显著高于1 h组,而3组弹性模量值比较差异无统计学意义。血清生化指标结果显示:与对照组相比,1.5 h组大鼠OC水平明显提升,且显著高于1 h组,而各组TRACP 5b值比较差异无统计学意义。骨形态计量学分析显示:与对照组相比,1 h组骨小梁厚度、数目和分离度不具有统计学差异,而1.5 h组骨小梁厚度和骨小梁数目均显著增加,骨小梁分离度显著下降;1.5 h组较1 h组骨小梁厚度和数目也明显增加,分离度减小。结论:50 Hz 0.6 mT低频脉冲电磁场干预大鼠1.5 h可以有效提高青年大鼠峰值骨密度和骨微结构,增强骨生物力学性能,促进大鼠血液中骨形成标记物的浓度,表明脉冲电磁场可作为预防和治疗骨质疏松的良好方法。

Objective:To compare effects of low frequency pulsed electromagnetic fields on bone quality in growing rats between 1 h and 1.5 h.Methods:Thirty male SPF SD rats aged 4 weeks selected,which with the average body weight(115.8±1.5) g,were divided into three groups according to random number table,10 rats in each group.Control groups put rats into electromagnetic field device with 1.5 h every day,the other two groups put rats in electromagnetic field for 1 h and 1.5 h with a50 Hz 0.6 mT intensity pulsed.The body weight of rats was weighed every 2 weeks and detected bone mineral density.Rats were sacrificed after 6 weeks to measure bone mineral density and biomechanical value of the right femur and lumbar vertebrae.Serum osteocalcin(OC) and tartrate-resistant acid phosphatase 5 b(TRACP 5 b) concentrations were determined by ELISA methods.After the magenta-picric acid staining,the micro-tissue structure of the right tibia was observed,and the parameters of trabecular bone were analyzed by IPP 6.0 software.Results:There were no statistical difference in body weight and organ coefficient among each groups at different times.Bone mineral density results showed that the body thickness of the 1.5 h group was significantly increased compared with control group at 6 weeks,and bone mineral density of femoral and vertebra in1.5 h group were higher than that of in 1 h group.The results of three-point femoral bending and vertebral compression test showed that the maximum load value of femur and vertebrae in 1.5 h group increased significantly compared with control group,and the maximum femoral load value in 1.5 h group was significantly higher than that of 1 h group,while there was no difference in elastic modulus values among each groups.Results of serum biochemical indicators showed that level of OC in1.5 h group was significantly increased compared with control group,and significantly higher than that of 1 h group,while no significant difference in TRAC.P 5 b values among each groups.Bone histomorphometry analysis results showed that there was no statistical difference in trabecular thickness,number and resolution between 1 h group and control group,trabecular bone thickness and number in 1.5 h group were increased,and trabecular bone resolution was decreased;The thickness and number of trabecular bone in 1.5 h group were also significantly increased compared with 1 h group,and the degree of resolution was reduced,and had significant difference between two groups.Conclusion:Intervention of 50 Hz 0.6 mT low-frequency pulsed electromagnetic field for 1.5 h could effectively increase peak bone mineral density and bone microstructure in young rats,enhance biomechanical properties of bone,promote concentration of bone formation markers in rat blood.The results indicating that pulsed electromagnetic field could be used as a good way to prevent and treat osteoporosis.