【作者】 刘钊；

【导师】 汲平；

【作者基本信息】 山东大学 ， 口腔医学， 2012， 硕士

【摘要】 目的：研究偏侧咀嚼后大鼠咬肌组织P38丝裂原活化蛋白激酶基因(Mitogen-activated protein kinase)表达的变化、Ca2+含量的变化及咬肌组织微观结构的改变,探讨P38基因在大鼠偏侧咀嚼模型咬肌适应性改建中的作用,为临床上颞下颌关节紊乱病中咀嚼肌紊乱疾病的治疗提供一定的理论依据。方法：8周龄雌性Wistar大鼠36只,体重200g-250g,随机分为实验组与对照组,拔除实验组左侧上颌磨牙建立偏侧咀嚼模型,并于拔牙后2周、4周、6周及8周分批处死,取双侧咬肌组织,应用原子分光光度法检测各组织Ca2+含量；荧光定量PCR (real-time PCR)法检测各组织中P38MAPK mRNA的相对表达量；制作超薄切片,透射电镜下观察各组织细胞超微结构的变化并计算Z线异常率。单因素方差分析和最小显著差t检验比较实验组拔牙侧与非拔牙侧以及对照组大鼠咬肌各项指标之间的差异,并分析Ca2+和P38MAPK mRNA相对表达量、Z线异常率之间的关系。结果：1)Ca2+含量的变化：各实验组拔牙侧的咬肌组织内Ca2+含量明显高于对照组(P<0.05)；实验组非拔牙侧咬肌组织内Ca2+含量在术后4周及6周时明显高于2周与8周；术后4周,实验组拔牙侧的咬肌组织内Ca2+含量明显高于非拔牙侧(P<0.05)2) P38mRNA相对表达量：术后2周与4周,拔牙侧明显高于非拔牙侧与对照组(P<0.05)。术后6周及8周,拔牙侧、非拔牙侧及对照组之间差异无统计学意义(P>0.05)。术后4周,拔牙侧咬肌组织中P38mRNA相对表达量较术后2周、6周及8周均有明显升高(P<0.05)。非拔牙侧咬肌组织中P38mRNA相对表达量在术后2周时最低。3)透射电镜观察各实验组拔牙侧、非拔牙侧及对照组咬肌组织超微结构,各实验组拔牙侧与非拔牙侧咬肌组织肌纤维排列不紧密,肌纤维束间可见裂隙,Z线、M线弯曲不连续,线粒体肿胀,线粒体空泡化,损伤表现拔牙侧重于非拔牙侧,且术后4周损伤表现最严重。4)Z线异常率：术后2周及4周,拔牙侧Z线异常率明显高于非拔牙侧及对照组(P<0.05),且非拔牙侧明显高于对照组(P<0.05)。术后6周及8周,拔牙侧、非拔牙侧及对照组Z线异常率之间差异无统计学意义(P>0.05)。各实验组拔牙侧Z线异常率术后4周时最高；从术后6周开始下降,术后8周降至最低。各实验组非拔牙侧Z线异常率,术后2周与术后4周之间差异无统计学意义(P>0.05),术后6周较术后4周下降(P<0.05)。结论：偏侧咀嚼可引起拔牙侧咬肌组织中P38MAPK mRNA表达增高,还可引起咬肌组织中Ca2+浓度升高,参与咬肌组织病理性改变,这与偏侧咀嚼致咀嚼肌功能紊乱有关。更多还原

【Abstract】 Objectives:To study the changes of P38mitogen-activated protein kinase mRNA expression, Ca2+concentration and ultrastructure of masseter muscle induced by unilateral chewing, and to discuss the role that p38played in these changes. This study intended to provide a theoretical basis for the treatment of masticatory muscle disorder syndrome.Methods:368-week-old female Wistar rats (provided by the Experimental Animal Center of Shandong University), weighing from250-300g, were randomly divided into control groups (n=3) and experimental groups (n=6). The animal models were established by extracting the left maxillary molars. The rats were killed in2weeks,4weeks,6weeks and8weeks after teeth extraction respectively and the masseter tissues were prepared to be tested. The Ca2+concentration was evaluated by atomic spectrophotometric method; the relative expression of P38MAPK mRNA was detected by real-time fluorescent quantitative PCR; the ultrastructural changes of myocytes were observed under the transmission electrion microscope (TEM) and the abnormal z-line rate was calculated.Results:1) Ca2+concentration:The Ca2+concentration of the masseter muscle in the extraction side was significantly higher than that of control groups (P<0.05), and Ca2+concentrations of the masseter muscle in the extraction side in4weeks and6weeks after teeth extraction were greatly higher than those in2weeks and8weeks after teeth extraction (P<0.05).4weeks after extraction, the Ca2+concentration of the masseter muscle in the extraction side was significantly higher than that in the non-extraction side(P<0.05).2) The relative expression of P38MAPK mRNA:2weeks and4weeks after extraction, the P38MAPK mRNA expression of the masseter muscle in the extraction sides were higher than that of the non-extraction sides significantly (P<0.05), and both of them were higher than that of the control groups significantly (P<0.05).6 weeks and8weeks after extraction, no significant differences were found among the extraction sides, the non-extraction sides and the control groups(P<0.05).4weeks after extraction, the expression of P38MAPK mRNA of the masseter muscle in the extraction sides reached the highest level.3) The ultrastructural changes of the rat masseter muscle under TEM:The muscle fibers in extraction side and non-extraction side showed intermyofibrillar loose arrangement, intermyofibrillar edema, broken curly z-lines and m-lines, swollen mitochondria. The impairment of the masseter musclein the4th week after teeth extraction was most severe and the masseter muscle of the extraction side showed a more severe pathological manifestation than that of the non-extraction side.4) The abnormal z-line rate:In the2th and4th week after teeth extraction, the abnormal z-line rate of the extraction side was higher than that of the non-extraction side (P<0.05), and both were higher than that of the control groups (P<0.05); While6and8weeks after teeth extraction, there were no significant difference among the extraction sides, the non-extraction sides and the control groups (P>0.05). The abnormal z-line rate of the extraction side reached the highest level in the4th week after teeth extraction, and the rate decreased from the6th week and continued to decrease to the lowest point in the8th week. In the2th and the4th week after teeth extraction, the abnormal z-line rate of the non-extraction sides showed no significant difference (P>0.05), and the rate began to decline in the6th week.Conclusions:long-term unilateral chewing may activate P38MAPK signal pathway via up regulating the expression of P38MAPK mRNA, which may participate in adaptive changes of masseter muscle.更多还原