功能矫形前伸下颌对大鼠咬肌TrkB表达影响的研究

目的：探讨功能矫形前伸大鼠下颌对青春期大鼠咬肌酪氨酸激酶受体-B（Tyrosine kinase receptor-B,TrkB）表达的影响。方法：将40只4周龄雄性SD大鼠随机分为实验组和对照组各20只,实验组大鼠佩戴自制的上颌功能矫治器,对照组不戴,分别在实验第3、7、14、21 d处死大鼠,通过免疫组织化学染色和RT-PCR检测两组大鼠咬肌中TrkB及其mRNA的表达。结果：实验3 d组、7 d组免疫组化阳性染色和mRNA的表达虽有增强,但与对照组相比,均无明显变化;实验14 d组、21 d组TrkB免疫组化阳性染色明显强于对照组,其mRNA表达结果亦同样高于对照组。结论：随着功能矫形前伸下颌时间的延长,TrkB表达含量逐渐增加,TrkB参与了咬肌在下颌前伸中的适应性改建活动。     

功能矫治器前伸大鼠下颌后咬肌中BDNF表达变化的研究

目的:观察功能矫治器前伸青春期大鼠下颌对咬肌中脑源性神经营养因子(brain-derived neurotropic factor,BDNF)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、14 d组、21 d组和同步正常对照组,共8组(n=5).实验组大鼠佩戴功能矫治器,建立下颌前伸动物模型;建模不同时间用免疫组织化学染色和RT-PCR检测各组大鼠咬肌中BDNF蛋白及其mRNA的表达水平.结果:与对照组相比,实验3d组、7d组BDNF蛋白和mRNA的表达均无显著性差异(P＞0.05);而实验14 d组、21 d组BDNF蛋白及mRNA表达水平均明显高于对照组(P＜0.05).结论:功能矫治器前伸下颌可使大鼠咬肌BDNF的表达水平随前伸时间的延长而逐渐增加,提示咬肌在下颌前伸中发生了适应性的改建活动.     

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领对青春期大鼠咬肌神经营养因子-3(neurotmphin-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、14 d组、21 d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...     

功能性矫治器引导大鼠下颌前伸后二腹肌中金属蛋白酶的表达研究

目的：研究功能性矫治器引导大鼠下颌前伸后二腹肌中基质金属蛋白酶（matrix metalloproteinase，MMPs）表达，探讨功能性矫治器作用过程中咀嚼肌适应性变化的生物学机制，为矫形性治疗提供新的理论依据。方法：采用实时荧光定量PCR和免疫组化染色法观察戴矫治器组和不戴矫治器组大鼠3、7、14、21d二腹肌前腹中MMP-2、MMP-9表达和表达差异。结果：①MMP-2mRNA、MMP-9mRNA表达在矫治前后存在差异：实验组3d、21d与对照组相比存在差异，实验组表达增加。实验组相比：21d比14d表达增加，21d比7d表达增加。对照组相比：21d比3d表达增加，14d比3d表达增加。②MMP-2、MMP-9蛋白表达差异：MMP-2蛋白表达水平在14d（p〈0．01）和21d（p〈0．05）组有差异，实验组表达增强。MMP-9蛋白表达水平在7d（p〈0.05）、14d（p〈0．05）和21d（p〈0．01）组均有差异，实验组表达增强。结论：功能性矫治器引导大鼠下颌前伸后咀嚼肌中MMP-2，MMP-9参与了咀嚼肌的适应性变化。     

功能矫形前伸大鼠下颌后翼外肌胰岛素含量变化的定量研究

目的：了解功能矫形前伸大鼠下颌后胰岛素对翼外肌适用性改建的作用。方法：采用放射免疫分析技术分别检测实验组和对照组大鼠翼外肌内胰岛素的含量。结果;功能矫形前伸下颌后,生长期大鼠外肌内胰岛素含量增加。结论：胰岛素在功能矫形前伸大鼠下颌后翼外肌的适应性改建中有重要作用。     

前伸青春期大鼠下颌后翼外肌细胞膜乙酰胆碱受体特性变化的研究

目的　研究功能矫形前伸青春期大鼠下颌后,翼外肌细胞膜乙酰胆碱受体最大结合容量和亲和性的变化,探讨功能矫形的神经肌肉调控机理。方法　选用40只5周龄SD雄性大鼠,随机分为实验组和对照组各20 只。实验组大鼠戴自制上颌功能矫治器,引导下颌前伸,对照组不做任何处理,分别在实验第1、3、7、14天处死大鼠,采用放射受体分析法测定2组大鼠翼外肌肌细胞膜上乙酰胆碱受体的最大结合容量和亲和常数。结果　实验组大鼠翼外肌细胞膜上乙酰胆碱受体最大结合容量明显大于对照组,具有高度亲和力。结论　功能矫形可增加翼外肌细胞膜上乙酰胆碱受体与乙酰胆碱的结合量。     

成年大鼠下颌功能性前伸后嚼肌浅层的超微结构改变

目的：观察成年大鼠下颌功能性前伸后嚼肌浅层的超微结构变化。方法：成年雄性SD大鼠40只,随机分为4个实验组和4个对照组,每组5只。实验组大鼠配戴固定的前伸下颌矫治器,对照组不配戴矫治器。分别于下颌前伸7d、14d、28d和60d处死实验组和对照组大鼠。取大鼠左右侧的嚼肌浅层,制作电镜标本,透射电镜下观察成年大鼠嚼肌浅层的超微结构变化。结果：实验组大鼠嚼肌浅层部分细胞在大鼠下颌功能性前伸7d时萎缩,前伸60d时形态不规则。实验组大鼠下颌前伸7d,部分嚼肌浅层细胞内肌丝断裂;前伸14d和28d时,嚼肌浅层细胞内肌丝的排列方向紊乱;前伸60d时,嚼肌浅层细胞内局部可见肌丝方向紊乱。大鼠下颌功能性前伸7d和14d时,实验组大鼠嚼肌浅层细胞内肌浆网多见;前伸28d时线粒体多见、形态改变;前伸60d时,肌丝间的线粒体仍多见。结论：成年大鼠下颌功能性前伸后嚼肌浅层细胞的形态、肌丝的排列和结构、线粒体和肌浆网的功能发生了改变。     

功能性矫治器引导大鼠下颌前伸后二腹肌中金属蛋白酶的表达研究

目的:研究功能性矫治器引导大鼠下颌前伸后二腹肌中基质金属蛋白酶(matrix metalloproteinase,MMPs)表达,探讨功能性矫治器作用过程中咀嚼肌适应性变化的生物学机制,为矫形性治疗提供新的理论依据.方法:采用实时荧光定量PCR和免疫组化染色法观察戴矫治器组和不戴矫治器组大鼠3、7、14、21 d二腹肌前腹中MMP-2、MMP-9表达和表达差异.结果:①MMP-2mRNA、MMP-9mRNA表达在矫治前后存在差异:实验组3 d、21 d与对照组相比存在差异,实验组表达增加.实验组相比:21 d比14 d表达增加,21 d比7 d表达增加.对照组相比:21 d比3 d表达增加,14 d比3 d表达增加.②MMP-2、MMP-9蛋白表达差异:MMP-2蛋白表达水平在14 d(p＜0.01)和21 d(p＜0.05)组有差异,实验组表达增强.MMP-9蛋白表达水平在7 d(p＜0.05)、14 d(p＜0.05)和21 d(p＜0.01)组均有差异,实验组表达增强.结论:功能性矫治器引导大鼠下颌前伸后咀嚼肌中MMP-2,MMP-9参与了咀嚼肌的适应性变化.     

食物硬度对离乳后大鼠咬肌神经营养因子3及其受体TrkC mRNA表达的影响

目的:检测不同硬度食物喂养下,大鼠在离乳后不同发育阶段咬肌神经营养因子3(Neurotrophin-3,NT-3)及其受体酪氨酸蛋白激酶C(Tyrosine kinase C,TrkC)的表达变化。方法:对出生后18d刚离乳的大鼠分别喂养固体、粉状鼠粮,于大鼠3w、4w、6w、9w龄时取表层咬肌,利用RT-PCR方法检测NT-3及其受体TrkC mRNA的表达变化情况。结果:在出生后3-9w内,粉、固体组大鼠咬肌NT-3 mRNA表达均明显下降(P<0.05),粉食组NT-3 mRNA在6w时表达低于固体组(P<0.05);TrkC mRNA在3-9w内持续下降,但粉、固体组间没有差异(P>0.05)。结论:粉食喂养能够降低离乳后大鼠咬肌NT-3 mRNA的表达,但对TrkC mRNA影响不大。     

功能矫治器引导大鼠下颌前伸咀嚼肌中MMPs表达

目的研究功能性矫治器引导大鼠下颌前伸后咀嚼肌中MMPs表达，探讨功能性颌骨矫形过程中咀嚼肌适应性变化的分子机制，为矫形治疗提供理论依据。方法采用RT—PCR，免疫组化染色法观察大鼠二腹肌前腹中MMP-2、MMP-9表达。结果①大鼠二腹肌前腹实验组和对照组中MMP-2 mRNA、MMP-9 mRNA均表达。②MMP-2蛋白表达水平在14d（P〈0．01）和21d（P〈0．05）组有差异；MMP-9蛋白表达水平在7d（P〈0．05）、14d（P〈0．05）和21d（P〈0．01）组均有差异，实验组均表达增强。结论①MMP-2、MMP-9参与了咀嚼肌正常的生长发育过程。②功能性矫治器引导大鼠下颌前伸后咀嚼肌中MMP-2、MMP-9参与了咀嚼肌的适应性变化。     

功能矫形前伸青春期大鼠下颌对翼外肌Na＋／K＋-ATPase功能活性的影响

目的：研究功能矫形前伸青春期大鼠下颌对翼外肌Na＋／K＋-ATPase功能活性的影响。方法：选用5w龄雄性SD大鼠70只，随机分为实验组和对照组，并各分为7个时间段，其中实验组大鼠佩戴可摘式上颔斜面导板功能矫治器。在不同的时间段，分别测定大鼠翼外肌Na＋／K＋-ATPase功能活性。结果：自矫治器佩戴第1-42d，实验组与对照组相比，Na＋泵活性均有显著性差异。Na＋泵活性自第1d开始上调，第21d达到最高峰，之后开始回落，在第28d、42d仍显著高于对照组。结论：生长发育对Na＋／K＋-ATPase功能活性没有显著影响，功能矫形治疗使翼外肌Na＋／K＋-ATPase功能活性产生了适应性增高。     

青春期大鼠前伸下颌后浅层嚼肌细胞膜乙酰胆碱受体研究

目的研究功能矫形前伸青春期大鼠下颌后，前伸下颌的浅层嚼肌细胞膜乙酰胆碱受体最大结合容量和亲和性的变化，探讨功能矫形的神经肌肉调控机制。方法选用40只5周龄SD雄性大鼠，随机分为实验组和对照组各20只。实验组大鼠戴自制上颌功能矫治器，引导下颌前伸，对照组不戴。采用放射受体分析法测定2组大鼠浅层嚼肌肌细胞膜上乙酰胆碱受体的最大结合容量和亲和性值。结果实验组大鼠浅层嚼肌细胞膜上乙酰胆碱受体最大结合容量明显增加，具有高度亲和力，大于对照组。结论功能矫形可增加浅层嚼肌细胞膜上乙酰胆碱受体与乙酰胆碱的结合量及亲和力，导致肌肉的结构与功能发生适应性改建。     

Adaptation of the lateral pterygoid and superficial masseter muscles to mandibular protrusion in the rat

It has been suggested that protrusion of the mandible results in an alteration of the functional activity of the lateral pterygoid muscle. If this is true, however, it is unclear whether this altered muscle function is a transient phenomenon with no long-term effect or whether it results in structural and functional adaptation of the involved musculature. The purpose of this study was to determine whether or not physiologic and metabolic changes take place within two jaw-protruder muscles--the lateral pterygoid muscle and the superficial masseter muscle--in rats after treatment with a protrusive appliance. Thirty 45-day-old male Sprague-Dawley rats were divided equally into experimental and control groups. The experimental animals wore bonded protrusive-type appliances for 2 weeks. Histochemical analysis of muscle fiber types and in vivo whole-muscle contractile-property analysis were used to evaluate structural and functional muscle adaptations. Mandibular length was slightly but significantly greater in the experimental group, indicating that the protrusive appliance had the expected positive effect on mandibular growth. Histochemically, the lateral pterygoid muscle in the experimental group exhibited a significantly greater area occupied by type I fibers at the expense of type IIb fibers. The superficial masseter muscle exhibited a significantly greater percentage of areas for both type IIa and type IIb fibers in the experimental group. Contraction time (TPT) increased in both muscles; that is, the muscles became slower. The histochemical and contractile-properties data indicate that the protrusive appliance caused the lateral pterygoid muscle to become more active with respect to tonic (postural) activity, whereas the superficial masseter muscle became more active phasically.     

Effects of denervation of the masseter nerve and bite raising on the masseter muscle of developing rats

The effects of masseteric denervation and bite raising on muscle fiber type differentiation were examined in the masseteric muscle of developing rats by histological and histochemical studies. Three-week-old Wistar rats had of their masseteric nerve at right side dissected, and a part of them were bite raised at anterior region one week after denervation for three weeks. The unoperated side and number of sham animals served as control. The animals were killed 3, 7, 10, 14, 21, 28, 35, 49 days later and then their masseter muscles were removed wholly and weighed them. After freezing of superficial and deep masseter muscles serial sections were made and HE staining carried out, ATPase staining and NADH-TR staining. On the photographs of the HE stained specimens, I measured the diameter of the muscle fibers. Gross findings on the denervated group, revealed the lower incisors shifted to unoperated side and on with the bite raising group, it shifted to the operated side. In denervated animals, the wet weight of the masseter muscle had decreased significantly. The masseteric muscle fibers in three-old-week control rats were undifferentiated on ATPase staining, but it became well differentiated on and after four-old-week. The superficial masseter of control mainly composed of type 2B fibers. In the deep masseter, about 10% type 1 and 2C fibers were found in limited area around the muscle spindles, and surrounded with type 2A and 2B fibers. In superficial masseter muscle of the denervated group, the percentage of type 2A fibers increased, and that of type 2B fibers decreased. The type 2C fibers were found from the 21st days after denervation. In deep masseter muscles, the percentage of type 1 and 2A fibers decreased, and that of type 2B and 2C fibers increased. In the denervated bite raising group, the composition of the muscle fiber type approached the control group. These results as above suggested, masseteric denervation causes degeneration of muscle fiber composition, and the possibility that early preventive treatment like bite raising may recover the muscle fiber composition normally.     

兔下颌角骨外板磨除术后咬肌不同处理方式与骨的适应性研究

目的:通过对兔下颌角骨外板磨除术后咬肌不同处理方式与骨的适应性相关指标的测定,比较咬肌不同处理方式与下颌骨变化的差异,为下颌角肥大手术方式的选择提供依据.方法:雌性家兔50只,3个月龄,分为2组,每组25只.左侧为手术侧,第1组行下颌角骨外板磨除术后将咬肌与翼内肌缝合,第2组行下颌角骨外板磨除术后咬肌不做缝合固定.每组在术后第1、2、4、8、12周时分别处死5只动物,手术侧咬肌称重,切取手术侧部分骨组织连同其上部分咬肌作病理切片,行HE染色,光镜下观察细胞形态,在200倍镜下用HJ-YG病理诊断分析系统测量肌小节长度和肌细胞面积,用游标卡尺测量下颌骨的厚度.采用SPSS 13.0软件包对数据进行统计学分析.结果:术后第4、8、12周,第2组咬肌重量减轻,与第1组相比有显著性差异(P＜0.05).术后4、8、12周,第2组下颌骨厚度未增加,第1组下颌骨厚度增加,有显著性差异(P＜.05).术后1、2、4周,第2组肌小节长度较第1组短,有显著性差异(P＜0.05).术后8、12周,第2组肌细胞面积较第1组小,有显著性差异(P＜0.05).结论:兔下颌角骨外板磨除术后肌小节长度、咬肌细胞面积、骨细胞等发生了适应性改建,尤其是游离咬肌后咬肌失去张力,其附着点上移,致使其发生明显萎缩.下颌骨愈合后厚度不增加.     

大鼠下颌功能前伸后激活髁突胰岛素样生长因子1基因表达

目的研究用功能矫治器前伸生长期大鼠下颌后，髁突软骨中胰岛素样生长因子（ＩＧＦ１）基因表达的变化规律，探讨功能矫形治疗的分子机理。方法将６０只雄性５周龄ＳＤ大鼠分为对照组和实验组，按１天、３天、１周、２周、３周和４周６个阶段，应用原位杂交技术研究髁突软骨中ＩＧＦ１ｍＲＮＡ的表达变化。结果正常生长期大鼠下颌髁突软骨有ＩＧＦ１ｍＲＮＡ表达；前伸大鼠下颌使髁突软骨细胞中ＩＧＦ１ｍＲＮＡ阳性强度和阳性细胞数目均增加。这一变化具有时间性，即实验３天后开始升高，实验后１周～２周达最高值，３周～４周时逐渐降低。结论功能前伸下颌后ＩＧＦ１ｍＲＮＡ转录升高，表明功能矫形后髁突软骨的生长改建可能是由于咀嚼肌牵张激活了ＩＧＦ１的基因表达。     

Effects of facial nerve denervation on masseter muscle of the rats

The effects of unilateral facial nerve denervation on the facial growth were studied by physiological and by histochemical examinations, using four- week- old Wistar rats. Two hundred twenty rats were divided into three groups: a control group, a group of subjects which resection of the left facial nerve, and a sham operation group. The rats were killed 1, 5, 10, 30, 60, 90, 120 days later. The superficial and deep masseter muscle fibers on both sides were classified into type I and type IIA or IIB on the basis of myosin ATPase activity and the diameter of these fibers was measured. The masseter muscles were stained with H&E and NADH-TR. Electromyogram recordings were analyzed during the rest position, stretch reflex, voluntary action and eating of solid foods in half of all groups. (1) The face of rats after denervation deviated to the right side, and the maxillo-facial skeleton was affected from the 30th day. (2) In the denervation groups the right side showed higher action potentials than the left side. (3) In the deep masseter muscles near muscle spindle in the denervated groups, the percentage of type I fibers on the right side increased on the 90th day, and that of type IIA fibers decreased on the 30th day. (4) The diameter of the deep masseter muscle fibers, of type I, IIA and IIB increased on the right side. These results prove that facial nerve denervation led to a functional disorder and a transformation of growing direction.