脉冲电磁场可抑制老年大鼠膝关节软骨退变

Pulsed electromagnetic fields inhibit knee cartilage degeneration in aged rats

背景:脉冲电磁场作为一种重要的物理治疗方法对骨关节炎的疗效确切,但其作用机制尚未完全明确。目的:观察脉冲电磁场对老年大鼠膝关节软骨退变的影响。方法:选取8只6月龄SD大鼠作为青年组,正常饲养8周,不做任何处理;将16只22月龄SD大鼠随机分为老年组(n=8)和脉冲电磁场组(n=8),对脉冲电磁场组大鼠进行脉冲电磁场干预,1次/d,每周5 d,连续干预8周,老年组正常饲养8周,不做任何处理。8周后麻醉处死所有大鼠,进行相关指标的检测。结果与结论:①与青年组相比,老年组大鼠血清Ⅱ型胶原C端肽水平升高(P<0.05);与老年组相比,脉冲电磁场组大鼠血清Ⅱ型胶原C端肽水平降低(P<0.05);②显微CT显示,与青年组相比,老年组大鼠胫骨的骨体积分数、骨密度、骨小梁数量均降低(P<0.05),骨小梁间隙增大(P<0.05);与老年组相比,脉冲电磁场组大鼠胫骨的骨体积分数、骨密度、骨小梁数量均升高(P<0.05),骨小梁间隙减少(P<0.05);③胫骨平台番红O-固绿染色显示,老年组大鼠关节软骨结构紊乱,软骨细胞明显减少,无法区分潮线;脉冲电磁场组上述情况有所改善;④RT-qPCR与Western blot检测显示,与青年组相比,老年组大鼠关节软骨及软骨下骨中基质金属蛋白酶1、基质金属蛋白酶13、P53、P21的mRNA与蛋白表达均升高(P<0.05);与老年组相比,脉冲电磁场组大鼠关节软骨及软骨下骨中基质金属蛋白酶1、基质金属蛋白酶13、P53、P21的mRNA与蛋白表达均降低(P<0.05);⑤结果表明,脉冲电磁场可能通过抑制P53/P21的表达抑制软骨细胞衰老,缓解关节软骨降解及抑制软骨下骨骨质疏松,改善老年大鼠骨关节炎。

BACKGROUND:Pulsed electromagnetic fields,as an important physical therapy,are exactly effective in the treatment of osteoarthritis,but the mechanism has not been fully clarified.OBJECTIVE:To observe the effect of pulsed electromagnetic field on the degeneration of knee joint cartilage in aged rats.METHODS:Eight 6-month-old Sprague-Dawley rats were selected as the young group and were subjected to normal diet with no treatment.Sixteen 22-monthold Sprague-Dawley rats were randomly divided into old group(n=8)and pulsed electromagnetic field group(n=8).The rats in the pulsed electromagnetic field group were subjected to a pulsed electromagnetic field intervention,once a day,5 days per week for continuous 8 weeks.The rats in the old group were given no treatment.All rats were anesthetized and executed after 8 weeks for the detection of relevant indexes.RESULTS AND CONCLUSION:Compared with the young group,serum type II collagen C-terminal peptide level was increased in the old group(P<0.05);compared with the old group,serum type II collagen C-terminal peptide level was decreased in the pulsed electromagnetic field group(P<0.05).Micro-CT showed that the bone volume fraction,bone mineral density,and number of bone trabeculae decreased(P<0.05)and the trabecular separation increased(P<0.05)in the tibia of rats in the aged group compared with the young group;and the bone volume fraction,bone density,and number of trabeculae increased(P<0.05)and the trabecular separation decreased(P<0.05)in the tibia of rats in the pulsed electromagnetic field group compared with the aged group.The tibial plateau Safranin O-fast green staining showed that the articular cartilage structure of rats in the aged group was disorganized,and the number of chondrocytes was obviously reduced,and the tidal line could not be distinguished.The above results were improved in the pulsed electromagnetic field group.RT-qPCR and western blot assay showed that the mRNA and protein expression levels of matrix metalloproteinase 1,matrix metalloproteinase 13,P53 and P21 in the articular cartilage and subchondral bone of rats were elevated in the aged group compared with the young group(P<0.05)and decreased in the pulsed electromagnetic field group compared with the old group(P<0.05).To conclude,pulsed electromagnetic fields may improve osteoarthritis in aged rats by inhibiting chondrocyte senescence,alleviating articular cartilage degradation and inhibiting subchondral bone osteoporosis through suppressing the expression of P53/P21.