目的·研究中频电刺激对SD大鼠下颌前伸后咬肌中神经营养因子3（neurotrophin-3，NT-3）表达的影响。方法·将60只雄性SD大鼠随机分为3组：空白对照组、条件对照组（戴用矫治器，不进行中频电刺激）和实验组（进行中频电刺激，同时戴用下颌前伸矫治器），每组20只。分别在第3、7、14和21日每组断颈处死5只大鼠，制备咬肌标本，用免疫组织化学染色以及实时荧光定量PCR检测各组大鼠咬肌中NT-3蛋白及mRNA的表达。结果·与空白对照组比较，条件对照组和实验组大鼠咬肌NT-3蛋白及mRNA的表达均呈先升高后降低的趋势；条件对照组第21日 NT-3蛋白及mRNA的表达仍高于空白对照组（均P<0.05），而实验组第21日 NT-3蛋白及mRNA表达已基本恢复至正常水平。结论·中频电刺激能加快功能矫治大鼠神经肌肉改建速率，缩短矫治时间。

Objective · To investigate the effect of medium frequency electrical stimulation on the expression of neurotrophin-3 (NT-3) in the mandibular protrusion of SD rats. Methods · Sixty male SD rats were randomly divided into three groups (n=20): blank control group, conditioned control group (treated with functional appliance, but without medium frequency electrical stimulation) and experimental group (treated with functional appliance and medium frequency electrical stimulation). Five rats in each group were sacrificed on the 3rd, 7th, 14th and 21st day to prepare the samples of masseter muscle. Immunohistochemistry and quantitative real-time PCR methods were used to detect the protein and mRNA expressions of NT-3 in the masseter muscle of rats. Results · The protein and mRNA expressions of NT-3 were increased firstly and then decreased in the conditioned control group and the experimental group, compared with those in the blank control group. Moreover, the protein and mRNA expressions of NT-3 in the conditioned control group were still higher than those in the blank control group on the 21st day (both P<0.05), while the protein and mRNA expressions of NT-3 in the experimental group almost returned to the normal level on the 21st day. Conclusion · Medium frequency electrical stimulation may accelerate the rate of neuromuscular reconstruction and shorten the time of functional orthopedic therapy in rats.