對于哺乳動物而言,在去負荷和高應激壓力條件下,如長期不活動、臥床、失重、缺氧和低溫等,較易發(fā)生骨骼肌萎縮和肌肉質量減少。然而,同樣處于長期不活動疊加低體溫等高應激條件下的冬眠哺乳動物,特別是小型冬眠哺乳動物,在歷經(jīng)長達數(shù)月的冬眠不活動期后,沒有或僅有很小程度的肌肉萎縮和肌肉質量的降低。在冬眠長時間不活動狀態(tài)下,小型冬眠哺乳動物通過何種機制避免了肌肉萎縮的發(fā)生?對此機制的探討不僅可為冬眠動物的生理適應機制增加新的有價值的科學資料,還有望為人類廢用性肌萎縮的防治提供新思路。關于骨骼肌萎縮的發(fā)生機制,一般認為,骨骼肌細胞中蛋白質合成過程受到抑制,而蛋白質降解過程得以增強,導致肌肉細胞蛋白質含量減少,這是導致肌肉萎縮和肌肉質量減少的主要原因和表現(xiàn)。PI3K/AKT/mTOR信號通路在調(diào)節(jié)細胞周期中起著至關重要的作用,在調(diào)節(jié)胞內(nèi)蛋白質合成方面亦扮演著重要的角色。mTOR通過調(diào)節(jié)骨骼肌合成代謝與分解代謝的信號傳導,可以控制骨骼肌的肥大與萎縮。已有的研究和我們之前的成果已經(jīng)證實,mTOR在維持冬眠動物骨骼肌質量中具有重要作用。因此,通過對PI3K/AKT/mTOR信號通路活性的調(diào)節(jié),實現(xiàn)肌細胞內(nèi)蛋白... 

【文章頁數(shù)】：66 頁

【學位級別】：碩士

【文章目錄】：
中文摘要
ABSTRACT
ABBREVIATIONS
CHAPTER1 Background
    1.1 Mammalian hibernation
    1.2 The changes in mammalian skeletal muscle during hibernation
    1.3 The MicroRNAs and its functions
        1.3.1 The discovery of miRNAs
        1.3.2 Introduction to miRNAs in hibernation
    1.4 The PI3K/AKT/mTOR pathway and its functions
    1.5 Study progress of miRNAs on PI3K/AKT/mTOR pathway in skeletal muscle
    1.6 Purpose and significance of present study
CHAPTER2 The changes of body mass and muscle mass of Daurian ground squirrels
    2.1 Daurian ground squirrels in present study
    2.2 The monitoring and grouping of Daurian ground squirrels
        2.2.1 Body temperature monitoring
        2.2.2 Experimental animal grouping
    2.3 Skeletal muscle sample collection
        2.3.1 Selection of semitendinosus muscle for present study
        2.3.2 Animal anesthesia
        2.3.3 Isolation of ST muscle
        2.3.4 The changes of body mass of Daurian ground squirrels
        2.3.5 The changes of ST muscle mass
    2.4 Brief summary
CHAPTER3 The expression levels of four miRNAs in ST muscle
    3.1 Selection of miRNAs
        3.1.1miR-206
        3.1.2miR-29b
        3.1.3miR-21a
        3.1.4miR-99b
    3.2 Experimental methods
        3.2.1 Identifying the miRNAs sequence
        3.2.2 Primer designing
        3.2.3 Main instruments and reagents
        3.2.4 Extraction of miRNAs from ST muscle
        3.2.5 cDNA synthesis from miRNA
        3.2.6 Real time-PCR detection of miRNAs
        3.2.7 Data statistics and analysis
    3.3 Experimental results
        3.3.1 The expression levels of miR-206 in ST muscle in different periods
        3.3.2 The expression levels of miR-29b in ST muscle in different periods
        3.3.3 The expression levels of miR-21a in ST muscle in different periods
        3.3.4 The expression levels of miR-99b in ST muscle in different periods
    3.4 Brief summary
CHAPTER4 The expression levels of PI3K/AKT/mTOR in ST muscle
    4.1 The PI3K/AKT/mTOR signaling pathway
    4.2 Experimental methods
        4.2.1 Main instruments and reagents
        4.2.2 The formulations of solutions
        4.2.3 Extraction of protein from ST muscle
        4.2.4 Western Blotting
        4.2.5 Data statistics and analysis
    4.3 Experimental results
        4.3.1 The expression levels of PI3K in ST muscle in different periods
        4.3.2 The expression levels of AKT in ST muscle in different periods
        4.3.3 The expression levels of mTOR in ST muscle in different periods
    4.4 Brief summary
CHAPTER5 Discussion and conclusion
    5.1 Discussion
    5.2 Conclusion
REFERENCES
ACKNOWLEDGEMENTS
Research achievements during the study for the Master’s degree



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