功能矫形前伸下颌对青春期大鼠咬肌NT-3表达影响的实验研究

目的：探讨功能矫形前伸下颌对青春期大鼠咬肌神经营养因子-3（neurotrophin-3，NT-3）表达的影响。方法：将40只4周龄雄性sD大鼠随机分为实验3d组、7d组、14d组、21d组和正常同步对照组，实验组大鼠佩戴功能矫治器，采用免疫组织化学染色法及RT-PCR检测大鼠咬肌NT-3及其mRNA的表达。结果：与对照组相比，实验3d、7d组咬肌纤维NT-3免疫阳性染色与mRNA表达均无明显变化；实验14d、21d组NT-3免疫阳性染色明显强于对照组，NT-3基因表达亦明显高于对照组。结论：功能矫形下颌前伸可致大鼠咬肌NT-3的表达发生改变，并且随着下颌前伸时间的延长，NT-3的表达量逐渐增加，NT-3表达改变提示咬肌在下颌前伸过程中发生了适应性的改建活动。

The changes of NT-3 expression in masseter muscles of adolescent rats after functional mandibular advancement

Objective ：To investigate the changes of neurotrophin-3 （ NT-3 ） expression in masseter muscles fibers of adolescent rats after functional mandibular advancement. Methods： Forty 4-weeks-old Sprague-Dawley rats were randomly assigned to experimental and control groups, as 3d-, 7d-, 14d- and 21d-group respectively. The functional appliances were only used in experimental groups, Immunohistochemistry staining method and polymerase chain reaction were used to detect the NT-3 expression of muscle fibers in rat masseter muscles. Results：The NT-3-1ike immunoreactivity and the expression quantity of NT-3 in 3d- and 7d- groups were no differences, but were higher in experimental 14d- and 21d-group than that in control 14d- and 21d-group, and the differences had statistical significance. Conclusions ： The functional mandibular advancement can impact the expression of NT-3 in masseter muscles of adolescent rats, accompanying the functional orthopedics, NT-3 expression is progressively increased. These changes may contribute to the proprioceptire adaptations to muscle rebuilding.