模拟失重对大鼠咬肌超微结构的影响

目的:应用透射电镜观察模拟失重对大鼠咬肌超微结构的影响。方法:24只Wistar大鼠,随机分为4组:模拟失重1w组,模拟失重2w组,模拟失重4w组和正常对照组。4组大鼠的饲养条件相同,分别于实验第1w、第2w和第4w处死大鼠,通过光镜和透射电镜分别观察大鼠咬肌组织病理学以及超微结构的变化情况。结果:实验第1w、2w和4w,对照组大鼠体重为328.67±15.65、330.00±12.38和326.33±15.88,实验组大鼠体重分别为274.50±41.66、295.00±19.92和288.84±22.41,后者大鼠体重增长速度明显下降,与对照组相比差异具有统计学意义(P<0.05)。光镜下观察,1w组大鼠咬肌部分肌纤维溶解、粗细不均,横纹不清晰;其他各实验组肌纤维横纹清晰,无明显肌纤维溶解破坏现象。透射电镜下观察,1w组大鼠咬肌肌原纤维溶解,Z线不连续,线粒体重度肿胀,基质密度降低,线粒体嵴减少,严重者可见空泡化;2w组大鼠线粒体轻度肿胀,肌原纤维周围线粒体数目增多;4w组大鼠咬肌线粒体未见明显肿胀。结论:模拟失重可导致大鼠咬肌发生可逆性的损伤。     

电离辐射对大鼠咬肌细胞ATP酶活性的影响

目的观察电离辐射对大鼠咬肌细胞ATP酶活性的影响,为放射性骨骼肌损伤的机制提供理论依据。方法一次性20 Gy X射线局部照射大鼠咬肌区,化学比色法检测照射后大鼠咬肌Na＋-K＋-ATP酶、Ca2＋-ATP酶、Mg2＋-ATP酶和Ca2＋-Mg2＋-ATP酶等活性的变化。结果照射后3天大鼠咬肌Na＋-K＋-ATP酶、Ca2＋-ATP酶、Mg2＋-ATP酶和Ca2＋-Mg2＋-ATP酶等活性分别降低了15.3%、15.1%、31.1%和16.4%,照射后30天分别降低了36.9%、35%、48.8%和36.9%。照射后30天,照射组大鼠咬肌ATP酶活性与对照组有显著性差异。结论 ATP酶活性降低,肌细胞离子代谢紊乱与放射性骨骼肌损伤有关。     

模拟失重及高+Gx对猴舌横纹肌细胞c-fos表达的影响

目的探讨模拟失重30d后高+Gx暴露对猴舌横纹肌细胞c-fos表达的影响。方法 16只雄性猕猴随机分为4组,即正常对照组(A)、30d模拟失重组(B),+13Gx/230s组(C)、30d模拟失重后超重组(D),其中D组根据过载峰值又分为+11Gx/270s(D1)、+13Gx/230s(D2)和+15Gx/200s(D3)。动物放血处死,解剖取材后,经10%中性福尔马林固定,石蜡包埋切片,采用组织病理学和免疫组化的方法,观察猴舌横纹肌组织结构及c-fos的表达情况。结果 A组可见正常的舌横纹肌结构,其他组舌横纹肌细胞结构基本正常,偶见细胞间质稀疏,横纹不清或消失。A组舌横纹肌细胞c-fos呈阴性表达,胞核、胞浆着色不明显。实验组舌横纹肌细胞"横纹"着深棕色,即胞浆呈强阳性表达。免疫组化光密度值显示,对照组与实验组,B组与D3组差异有统计学意义(P<0.05)。结论 30d模拟失重和高+Gx均可引起舌横纹肌细胞c-fos强阳性表达,舌横纹肌受到了一定程度的损伤。模拟失重降低了舌横纹肌细胞对+Gx的耐受性,两者具有一定的协同性。     

电离辐射对大鼠咬肌细胞超微结构及糖原含量的影响

目的观察电离辐射对大鼠咬肌形态学和糖原含量的影响。方法28只雄性SD大鼠,照射组16只,对照组12只。照射组大鼠腹腔注射2%盐酸氯胺酮麻醉后,一次性20GyX射线局部照射咬肌区。对照组只麻醉,但不照射。记录大鼠体重变化,H＆E染色、PAS染色、电镜观察形态学变化,蒽酮法测定肌糖原含量变化。结果照射组大鼠体重暂时性降低,持续到第11天。照射后第12天,照射组大鼠体重开始同对照组一样增长。照射后大鼠咬肌没有明显炎症细胞浸润,没有明显肌纤维溶解破坏等。照射后部分肌浆网肿胀扩张,部分线粒体空泡性变明显。照射后3天,照射组大鼠咬肌糖原含量减少约25%,与对照组有显著性差异。照射后30天,照射组与对照组没有显著性差异。结论照射后大鼠咬肌形态和代谢发生了变化。     

软食喂养对发育中大鼠咬肌乙酰胆碱受体亚基mRNA表达的影响

目的：检测不同硬度食物喂养下,大鼠在咀嚼形成的不同阶段,咬肌乙酰胆碱受体亚基mRNA（nicotinic acetylcholine receptor,nAchR）的表达变化。方法：40只出生后18d的大鼠,随机分为硬食组、软食组,分别喂养营养成分相同的固体、粉状鼠粮,于大鼠3w、4w、6w、9w龄时取表层咬肌,半定量RT-PCR方法检测nAchRγ/ε/δ亚基mRNA的表达变化情况。结果：3周时两组大鼠咬肌γ-nAchR mRNA表达均较低,软食组强于硬食组（p〈0.05）,4周时,硬食组没有γ-nAchR mRNA表达,软食组仍有微弱表达,6～9周两组均无γ-nAchR mRNA表达。两组大鼠ε-nAchR mRNA表达变化没有显著差异,4～9周表达均明显低于3周（p〈0.05）。3～9周龄两组大鼠咬肌δ-nAchR mRNA表达均呈下降趋势,软食组下降程度更为明显,9周时明显低于硬食组（p〈0.05）。结论：大鼠咬肌γ/ε-nAchR亚基转化在出生后3～4周完成,软食喂养可以延缓γ-nAchR的消亡与γ/ε-nAchR亚基转化,但不能阻止这一过程;软食喂养对不同nAchR亚基mRNA表达的影响具有选择性。     

模拟失重及高+Gx对猴舌横纹肌细胞结构及HSP70表达的影响

目的探讨模拟失重及高+Gx对猴舌横纹肌组织结构和热休克蛋白70(heat shock protein 70,HSP70)表达的影响。方法 12只雄性猕猴随机分为4组,正常对照组(A)、30d模拟失重组(B),+13Gx/230s组(C)、30d模拟失重后超重组(D),其中D组根据过载峰值又分为+11Gx/270s(D1)、+13Gx/230s(D2)和+15Gx/200s(D3)。动物放血处死后取材,采用组织病理学和免疫组化的方法,观察猴舌横纹肌组织结构及HSP70的表达情况。结果 A组可见正常的舌横纹肌结构,其他组舌横纹肌细胞结构基本正常,偶见细胞间质稀疏,细胞排列紊乱以及横纹不清或消失。A组舌横纹肌细胞HSP70呈阴性表达,细胞核与细胞浆均无明显着色;B组、C组和D组舌横纹肌细胞胞核与胞浆均着色明显,呈阳性表达,较A组变化显著。HSP70免疫组化积分显示,D组比B组和C组变化显著(P<0.05),但D1、D2、D3无明显差别(P>0.05)。结论 30d模拟失重和高+13Gx/230s均可使猴舌横纹肌细胞产生应激反应,引起HSP70的表达增强,并可能伴有损伤。模拟失重与过载超重具有协同作用,两者可能加重了对舌横纹肌的影响。     

雌激素对大鼠咬肌热休克蛋白70表达的影响

目的探讨雌激素对大鼠咬肌热休克蛋白（HSP）70表达的影响。方法将60只雌性未孕12周龄Sprague-Dawley大鼠随机分成3组,每组20只。假手术组大鼠在轻微骚动卵巢后缝合,去卵巢组大鼠去除卵巢后缝合,雌激素替代组大鼠去卵巢后接受雌二醇替代治疗。在实验的第4周和8周,每组各处死10只大鼠,采用免疫组织化学方法研究雌激素对大鼠咬肌HSP70表达的影响。结果4周时3组大鼠咬肌HSP70的表达无明显差异（P>0.05）;8周时去卵巢组大鼠HSP70的表达下降,与假手术组、雌激素替代组之间的差异有统计学意义（P＜0.05）,而假手术组与雌激素替代组之间的差异无统计学意义（P>0.05）。结论雌激素水平降低会导致大鼠咬肌HSP70的表达下降,雌激素替代疗法可以预防HSP70表达降低。     

电离辐射对大鼠咬肌钙泵活性和表达的短期影响

-ATP酶本身功能异常造成的.     

情绪应激对大鼠咬肌超微结构的影响

目的：应用电镜观察情绪应激对大鼠咬肌超微结构的影响。方法：48只Wistar大鼠，随机分为3组：情绪应激组Ⅰ（3周应激组），情绪应激组Ⅱ（5周应激组）和空白对照组。前两组大鼠同处交流箱内，3组大鼠同条件饲养，分别于3、5周处死大鼠，电镜观察咬肌超微结构变化。结果：3周情绪应激组大鼠咬肌线粒体出现水肿，基质密度降低，线粒体嵴减少，肌纤维微血管内出现充血性改变；5周情绪应激组大鼠咬肌线粒体则出现严重空泡性变，肌纤维微血管出现更为严重的充血性改变。结论：情绪应激可导致咬肌纤维问微血管充血性改变和线粒体损伤，并且这种变化随时间的延长而加重。这种影响可能是咀嚼肌紊乱（masticatorymusclesdysfunction。MMD）的原因之一。     

情绪应激对大鼠咬肌能量代谢的影响

目的：研究情绪应激对大鼠咬肌能量代谢的影响。方法：48只Wistar大鼠,随机分为情绪应激组和空白对照组各24只,应激组大鼠依应激时间分为1周组（Ⅰ组）、3周组（Ⅱ组）和5周组（Ⅲ组）：另外24只大鼠仅接受足部电击,在实验中作为应激源,不进入实验处理。应激组大鼠和接受足部电击大鼠同处交流箱内,所有大鼠同条件饲养,分别于1周、3周、5周处死应激组和对照组大鼠,检测咬肌Na^＋-K^＋ATP酶活性,Ca^2＋-ATP酶活性,乳酸脱氢酶（LDH）活性以及肌肉乳酸（LD）含量的变化。结果：应激源刺激发生后,随着应激时间的延长,咬肌Na^＋-K^＋ATP酶活性与Ca^2＋-ATP酶活性呈现逐渐下降趋势,同时,大鼠咬肌组织中LD含量逐渐增高,LDH活性呈逐渐升高的趋势。结论：情绪应激可以引起大鼠咬肌能量代谢发生变化,这种变化可能是引起咬肌超微结构发生改变、导致咀嚼肌紊乱疾病的原因之一。     

软食喂养对发育中大鼠咬肌脑源性神经营养因子及其受体mRNA表达影响的研究

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脑源性神经营养因子(brain-derived neurotrophicfactor,BDNF)及其受体酪氨酸蛋白激酶B(Tyrosine Kinase B,TrkB)mRNA的表达变化。方法出生后18 d刚离乳的大鼠40只,分为硬食组、软食组,分别喂养营养成分相同的固体、粉状鼠粮,于大鼠3、4、6、9周龄时取表层咬肌,利用半定量RT-PCR方法检测BDNF及其受体TrkB mRNA的表达变化情况。结果3-9周龄2组大鼠咬肌均有BDNF/TrkB mRNA表达,3周龄时,2组表达均较低,没有显著差异;4周龄时,2组大鼠咬肌BDNF/TrkB mRNA均较3周时有显著的增加,但软食组增加幅度低于硬食组;6-9周龄时BDNF/TrkB mRNA表达降低,2组间没有显著差异。结论BDNF/TrkB mRNA在咀嚼形成关键期(P3-4周)表达显著增强,软食喂养能够降低此阶段大鼠咬肌BDNF/TrkB mRNA表达,BDNF/TrkB可能与咀嚼形成有密切关系。     

Effect of scanning level and muscle condition on ultrasonographic cross-sectional measurements of the anterior masseter muscle

With the disadvantage of computed tomography showing cumulative biological effects and magnetic resonance imaging posing a problem in clinical availability and cost, several authors described the technique of ultrasonography to measure non-invasively local cross-sectional dimensions (LCSDs) of masseter muscle sites. However only few studies addressed the issue of 'technique-related factors for intra- and inter-observer reliability' to gain more consistent testing and diagnosis. The purpose of the present study was to determine (1) whether the scanning level and/or the muscle condition may affect LCSD measurements and (2) whether measurements made at identical levels may be reproducible. The study included 35 subjects with signs and symptoms of temporomandibular disorders. Bilateral ultrasonographic investigation was performed with a linear (B-scan) 7.5 Mhz small-part transducer to register LCSDs of the anterior masseter muscle on three different levels. Scans were made on the relaxed and contracted muscle. Measurements were made in two sessions with a time interval of at least 5 min. Data were analysed for reproducibility by using the intra-class correlation coefficient (ICC) and the method error (ME). Scanning level and muscle condition had a significant effect on muscle measurements (P = 0.000). There was no difference in LCSD between the right and left muscle (P = 0.531). Measurements recorded at a given site were consistent across the testing sessions (P = 0.058). The scanning level with highest reproducibility was halfway between the origin and insertion (ICC = 0.92; ME = 6.2%). The data suggest that ultrasonography is a reliable method for measuring LSCDs of the anterior masseter muscle.     

外源性磷酸肌酸对偏侧咀嚼大鼠咬肌组织影响的研究

目的研究能量治疗对偏侧咀嚼大鼠咬肌组织中Ca2+、Ca2+-ATP酶活性的影响,探讨外源性能量物质磷酸肌酸（CP）对偏侧咀嚼大鼠咬肌组织的保护作用。方法将20只大鼠随机分为4组,分别记为A组：磷酸肌酸钠对照组;B组：磷酸肌酸钠实验组;C组：生理盐水对照组;D组：生理盐水实验组。采用原子吸收分光光度法测定Ca2+质量分数;运用Ca2+-ATP酶试剂盒测定Ca2+-ATP酶活性;透射电镜观察咬肌组织超微结构的变化。结果1）D组拔牙侧Ca2+质量分数较其非拔牙侧（P=0.007）、C组（P=0.009）、B组拔牙侧（P=0.01）均有明显升高;2）D组拔牙侧Ca2+-ATP酶活性较其非拔牙侧（P=0.001）、C组（P=0.003）、B组拔牙侧（P=0.001）均有明显降低;3）透射电镜下观察到B组拔牙侧咬肌组织超微结构与正常对照组相近,而D组拔牙侧咬肌组织超微结构与正常对照组相差较大,损伤表现拔牙侧重于非拔牙侧。结论外源性能量物质磷酸肌酸钠对偏侧咀嚼大鼠咬肌组织有一定的保护作用,有可能成为改善咀嚼肌损伤的一个新途径。     

Adaptation of normal and hypofunctional masseter muscle after bite-raising in growing rats

The aim of this study was to analyze the effects of prolonged muscular elongation induced by bite-raising on the length of the muscle belly, sarcomeres and aponeurosis of the anterior deep masseter in the growing rat. Another aim was to determine the role of different functional conditions of this muscle in the adaptation process. Ninety-six young male rats were split into two groups: one was fed a hard diet and the other a soft diet to develop different functional capacities in the masticatory muscles. After 2 wk, half of the rats in both groups were fitted with an appliance that raised the bite by 2 mm. The measurements on the muscles were performed in situ. The insertion of the appliance stretched the anterior masseter muscle. After 4 wk, the vertical dentoskeletal dimension, the muscle belly, and the sarcomeres showed no difference in length among the groups. However, the aponeurosis was longer in the rats wearing the appliance compared to the controls, and among the bite block groups it was longer in the rats fed a hard diet. Length adaptation occurred in the aponeurosis. Clinically this may imply a need for reactivation of functional appliances to increase their efficiency, at a rate possibly depending on masseter muscles functional condition.     

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。     

Effects of metabolic syndrome on masseter muscle of male Wistar rats

The aim of this study was to investigate the association between metabolic syndrome (MetS) and the metabolic indicators of masticatory muscles in an animal model. A total of 16 male Wistar rats were used. To induce MetS, 10 rats were fed with standard rat chow and 32% sucrose solution ad libitum for 16 wk. Six rats fed with standard rat chow and water ad libitum formed the control group. All rats were killed at week 16, and the right superficial masseter muscles were harvested. Metabolic indicators of masticatory muscle metabolism, including antioxidant enzyme activities, ion transport ATPase activities, and the levels of macro and trace elements, were determined in the muscles. Superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activities were significantly decreased by 32%, 26%, 33%, and 16%, respectively, in the MetS group. Na⁺/K⁺‐ATPase activity was significantly decreased in the MetS group by 54% compared with the control group. The levels of chromium and selenium were significantly decreased, and the level of copper was increased, in the MetS group compared with the control group. These results show that significant alterations occurred in antioxidant defense mechanisms, ion transport mechanisms, and trace element levels of masseter muscles in MetS.