Cellular and molecular mechanism of skeletal muscle atrophy and anti-atrophic muscle training

Objective: To review the research progress of cellular and molecular mechanism of skeletal muscle atrophy, and the effects and mechanisms of anti-atrophic muscle training and medication against atrophy. Data sources: The relevant articles on skeletal muscle atrophy published between March 1988 and March 2007 were searched for in PubMed with the key words of "skeletal muscle, atrophy, exercise, ubiquitin-proteasome, apoptosis" in English. Simultaneously, the relevant articles published between Match 2002 and May 2005 were searched in Wanfang Database with the key words of "skeletal muscle, apoptosis, training" in Chinese. Study selection: The data were checked firstly, and the articles on skeletal muscle atrophy were selected for the full-texts. Inclusive criteria included the articles on protein generalization, apoptosis, anti-atrophic muscle training end medication on skeletal muscle atrophy, and others were excluded. Data extraction: Totally 61 articles on skeletal muscle atrophy were found out, and 33 articles were selected according to the inclusive criteria. Data synthesis: Skeletal muscle atrophy is usually caused by three factors: aging, disuse and related diseases: Denervation contributes to research atrophy at cellular and molecular level; both protein synthesis/ degradation and cell proliferation/apoptosis reveal the mechanism of atrophy at different points of view. Disuse models were widely used to search medicament and anti-atrophic muscle training against atrophy, but these researches could not draw consistent conclusions. The resistant/ retardant effects of exercise on atrophy were shown in gene expression of structural proteins, cell signal transduction, hormone, cytokine and so on. Medication and physical therapy had an inneglectable effect on anti-atrophic muscle training. Conclusion: Skeletal muscle atrophy has a heavy correlation with excessive protein degradation and apoptosis. The resistant/retardant effects of exercise on atrophy are correspondingly shown at cellular and molecular levels. Medication and physical therapy have a positive effect on atrophy, but reasons are unclear.