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1、大鼠失重性肌萎缩运动恢复中大鼠失重性肌萎缩运动恢复中 MHCMHC 的转变和的转变和 myogeninmyogenin的作用的作用论文摘要中、长期失重或模拟失重条件下,人或动物的肌肉组织,特别是下肢抗重力肌出现了明显的肌肉萎缩。肌肉萎缩,特别是慢肌比目鱼肌的萎缩已被许多研究证实,肌萎缩伴有 MHC 由慢速型(型)向快速型(型)的转变。一般认为,耐力性训练可观察到 MHC 由快型到慢型的转变。myogenin 在成肌分化过程中起着决定性的作用, 是继生长激素(GH)、胰岛素样生长因子(IGF)之后新发现的功能基因。成肌调节因子(MRFs)家族中的 MyoD 和 myogenin 两个因子在快慢肌
2、中选择性表达,MyoD 在快肌中表达高,myogenin 在慢肌中表达高,由和a 肌纤维组成的肌肉部位 myogenin 表达高,MyoD 表达低。相反,由b、x 组成的肌肉部位MyoD 表达高,而 myogenin 表达低。本实验设计模拟失重模型及游泳训练模型,将myogenin 在 MHC 转换中的作用与肌肉萎缩后运动恢复结合起来进行研究。 将筛选出的 32 只雄性 SD 大鼠随机分成 4 组,每组各 8 只:对照组(C)、模拟失重组(U)、自然恢复组(UC)和游泳恢复组(UE),建立后肢悬垂模拟失重模型和游泳训练模型,计量各组比目鱼肌肌湿重、肌纤维横截面积和肌内MHC-、MHC-a、my
3、ogenin mRNA 的表达。 结果显示: (1)模拟失重 4 周组(U 组)肌湿重、横截面积显著低于对照组(C 组),游泳恢复组(UE 组)与自然恢复组(UC 组)相应指标显著高于 U 组。 (2)模拟失重 4 周组(U 组)与对照组(C 组)相比,myogenin mRNA 表达方面有下降趋势,但无显著性差异;MHC-显著下降,MHC-a 显著下降。 (3)游泳恢复组(UE 组)与自然恢复组(UC 组)相比,myogenin mRNA 表达方面有上升趋势,但无显著性差异;MHC-和 MHC-a 有上升趋势,但无显著性差异。 结论: (1)本论文中失重性肌萎缩模型是可行的模拟失重模型,4
4、周模拟失重后,肌纤维横截面积显著下降,肌肉发生萎缩。 (2)myogenin 可能不可以作为肌萎缩变化的分子生物学指标。 (3)小强度耐力训练不是抗肌萎缩的昀合适练习方法。 (4)myogenin 可能在转录水平调节 MHC-表达。关键词:失重,肌萎缩,myogenin, MHCABSTRACT Under the conditions of medium and long-term microgravity or simulated microgravity,muscle atrophy is clear in the human or animal muscle tissue,especi
5、ally the anti-gavity muscles of lower limbs.Muscle atrophy,especially of slow muscle-soleus atrophy,have been confirmed by many studies,and the muscle atrophy lead to muscle fiber type changing from the slow-typetypeto the fast-typetype.It is generally believed that endurance training can result in
6、MHC type changing from the fast-type MHC to the slow-type.Myogenin which plays a key role in the process of myoblast differentiation is the newly discovered function following with growth hormoneGHand insulin-like growth factor IGFMyoD and myogenin which are from myogenic regulatory factors MRFs fam
7、ily selectively express in the fast and slow muscle which MyoD expresses more in the fast muscle and myogenin expresses more in the slow muscle,what is more, the expression of myogenin in the muscle that is componented byanda muscle fiber is much more than the expression of MyoD. In contrast, it was
8、 found that the expression of MyoD in the muscle that is componented byb andx muscle fiber is much more than the expression of myogeninThis experiment would design the model of simulated microgravity and swimming,and study the function of myogenin in transformation of MHC combined with the recovery
9、of exercise from muscle atrophy32 male SD rats would randomly divided into 4 groups ,and there are eight rats in each group: control groupC, simulated microgravity group U, natural recovery group UC and the recovery of swimming group UETo set up hindlimb overhanging model of simulated microgravity a
10、nd swimming training model, what is more,to measure the soleus muscle wet weight and muscle fiber cross-sectional areaCSA,as well as the MHC-、MHC-a, myogenin mRNA expression in the muscleThe results showed that: 1 The muscle wet weight and cross-sectional area of U group was significantly lower than
11、 that of C group, and the corresponding index of UE group and UC group was significantly higher than that of U group2 Compared with the C group, there is a downward trend in myogenin mRNA expression of U group, but no significant difference,what is more,MHC-and MHC-a decreased significantly3 Compare
12、d with the UC group, there is a upward trend in myogenin mRNA expression of UE group, but no significant difference,what is more, there is a upward trend in MHC-and MHC-a mRNA expression of UE group, but no significant differenceConclusion: 1 In this paper, the model of muscular atrophy is a viable
13、one of simulated microgravity.After simulated microgravity of 4 weeks, cross-sectional area of muscle fiber is significantly decreased2Myogenin may not be regarded as the indicators of molecular biology of the change of muscle atrophy3 Low-intensity endurance training is not be the most appropriate
14、methods to recover the muscle atrophy 4Myogenin may regulate the expression of MHC-at the transcriptional levelKey words: microgravity, muscle atrophy, myogenin, MHC 目录 第一部分 文献综述 1 1.失重/模拟失重和肌萎缩概述及其研究进展 1 1.1 模拟失重的实验模型及验证肌萎缩的方法 1 1.1.1 模拟失重的实验模型. 1 1.1.2 验证肌萎缩的方法 1 1.2 失重/模拟失重条件下肌肉的形态结构. 2 1.2.1 肌肉重
15、量和体积改变. 2 1.2.2 肌纤维横截面积 2 1.2.3 肌纤维类型改变 2 1.3 失重性肌肉萎缩的防治措施 3 1.3.1 运动及功能训练 3 1.3.2 物理治疗 3 1.3.3 药物治疗 3 2.成肌调节因子及其研究进展 4 2.1 成肌调节因子的构成及肌细胞生成素(myogenin)的概述 4 2.1.1 成肌调节因子的分子构成 4 2.1.2 肌细胞生成素 myogenin 的结构及其作用机制 5 2.2 成肌调节因子在肌肉发育过程中的作用. 5 2.3 成肌调节因子调节肌肉表达的机制. 5 2.4 运动对成肌调节因子的表达影响. 6 3.肌球蛋白重链 MHC 概述及其研究进
16、展. 7 3.1 肌球蛋白的结构与功能 7 3.1.1 肌球蛋白的结构 7 3.1.2 肌球蛋白的功能 8 3.1.3 肌球蛋白重链异构型的分类. 8 3.2 运动对肌球蛋白重链 MHC 表达的影响. 9 3.2.1 耐力练习对肌球蛋白重链的影响 9 3.2.2 抗阻力练习对肌球蛋白重链的影响 10 3.2.3 低氧及低氧训练对肌球蛋白重链表达的影响. 11 第二部分 实验部分 12 前言. 12 1.材料与方法 12 1.1 实验动物 12 1.2 模型的建立 13 1.2.1 模拟失重模型 13 1.2.2 游泳训练模型 13 1.3 主要试剂 14 1.4 主要仪器 15 1.5 样本的采集 15 1.6 骨骼肌肌纤维横截面积的测定?HE 染色 15 1.7 骨骼肌 myogenin、MHC-I、MHC-IIa mRNA 表达的测定?R T -PCR. 16 1.7.1 RNA 提取 16 1.7.2 逆转录反应 16 1.7.3 PCR. 17 1.8 统计方法 17 2.结果与分析 18 2.1 比目鱼肌湿重. 18 2.
