去负荷肌萎缩小鼠运动耐力的变化及机制研究

发布时间：2018-10-09 09:34

【摘要】：实验目的：长时间去负荷会导致骨骼肌的重量丢失和肌纤维类型的转变,进而引起骨骼肌收缩特性和生理功能的变化,但是否对骨骼肌运动耐力产生影响未见报道。本研究拟聚焦在去负荷诱导不同程度肌萎缩的发生是否对运动耐力的产生影响,并探讨其分子机制。实验方法：雄性C57BL/6小鼠,随机分为去负荷0、7、14及28天组(n=7)。去负荷结束后,将每组小鼠置于跑台中以15m／min匀速运动,通过测定运动耗竭时间和距离以比较其运动耐力。通过组织学、免疫印迹及免疫组化等实验方法,对比观察肌纤维的横截面积、TNNI1和TNNI2蛋白表达以及快慢肌纤维含量的变化,研究去负荷肌萎缩对小鼠运动耐力影响的分子机制。实验结果：①去负荷诱导肌萎缩形成过程中,至去负荷28天,小鼠后肢背侧腓肠肌、比目鱼肌和跖肌肌肉重量持续丢失。②相对于对照组,去负荷7、14和28天后小鼠运动耐力分别下降至对照组的69.8%(P0.001)、34.5%(P0.001)、28.3%(P0.001)。③HE染色结果表明,去负荷7天后,腓肠肌、比目鱼肌和跖肌肌纤维横截面积即明显减少,至去负荷14天后肌纤维萎缩程度最大,但在去负荷28天后肌纤维横截面积又略有增加,但同对照组相比仍明显减少。④免疫印迹和免疫组化的结果表明,在去负荷诱导的肌萎缩过程中,腓肠肌、比目鱼肌和跖肌中的慢肌纤维蛋白及慢肌纤维含量下降,而快肌纤维蛋白和快肌纤维含量增多。结论：①在去负荷诱导的肌萎缩过程中,随着去负荷时间的延长,小鼠后肢背侧肌肉重量持续丢失,肌纤维横截面积呈现先下降后上升的趋势。②在去负荷诱导的肌萎缩过程中,随着去负荷时间的延长,运动耐力持续下降。③肌纤维萎缩造成的骨骼肌收缩特性的改变可能是造成去负肌萎缩后运动耐力下降的直接原因。④在去负荷诱导的肌萎缩过程中,腓肠肌、比目鱼肌和跖肌内慢肌纤维比例的减少和快肌纤维比例的增加是造成其运动耐力下降的分子机制。
[Abstract]:Objective: long time deloading will lead to the loss of skeletal muscle weight and the change of muscle fiber type, which will lead to the change of skeletal muscle contractility and physiological function. However, the effect on skeletal muscle exercise endurance has not been reported. This study is intended to focus on the effects of deload-induced muscle atrophy on exercise endurance and its molecular mechanism. Methods: male C57BL/6 mice were randomly divided into 2 groups (n = 7). After removing the load, each group of mice were placed in the running table to exercise at 15m/min uniform speed. The exercise exhaustion time and distance were measured to compare their exercise endurance. The changes of TNNI1 and TNNI2 protein and the content of fast and slow muscle fibers in muscle fibers were observed by histological, immunoblotting and immunohistochemical methods, and the molecular mechanism of the effects of unloaded muscle atrophy on exercise endurance of mice was studied by comparing the expression of TNNI1 and TNNI2 protein and the content of fast and slow muscle fibers in muscle fibers. Results the weight of gastrocnemius muscle, soleus muscle and metatarsal muscle of the hind limb of the mice were continuously lost by the weight loss of 2. 2 compared with the control group during the muscle atrophy induced by 1: 1 decompression until 28 days after decompression. The results showed that the cross sectional area of gastrocnemius muscle, soleus muscle and metatarsal muscle decreased significantly after 7 days of loading, and decreased to 69.8% (P 0.001) or 34.5% (P 0.001) of the control group respectively, and the results showed that the cross-sectional area of gastrocnemius muscle, soleus muscle and plantar muscle was significantly decreased after 7 days of loading. After 14 days, muscle fiber atrophy was the largest, but the cross-sectional area of muscle fiber increased slightly after 28 days. However, compared with the control group, the results of immunoblotting and immunohistochemistry showed that there was no significant difference between the control group and the control group. In the course of muscle atrophy induced by decompression, the contents of slow muscle fibrin and slow muscle fiber in gastrocnemius muscle, soleus muscle and plantar muscle decreased, while fast muscle fibrin and fast muscle fiber content increased. Conclusion in the process of muscle atrophy induced by decompression, the weight of muscle in the dorsal side of the hind limb of the mice continued to lose with the prolongation of the time of deloading. The cross sectional area of muscle fiber decreased first and then increased. 2 in the course of muscle atrophy induced by desorption, with the prolongation of the time of deload, the cross-sectional area of muscle fiber decreased firstly and then increased. The change of contractile characteristics of skeletal muscle caused by muscle fiber atrophy caused by continuous decline of exercise endurance may be the direct cause of the decrease of exercise endurance after atrophic of de-negative muscle. 4 in the course of muscle atrophy induced by decompression, gastrocnemius muscle, and gastrocnemius muscle. The decrease of the proportion of soleus muscle and plantar slow muscle fiber and the increase of fast muscle fiber ratio are the molecular mechanisms that cause the decrease of exercise endurance of soleus muscle and metatarsal muscle.
【学位授予单位】：北京体育大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：G804.2

【相似文献】