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Age-related differences in apoptosis with disuse atrophy in soleus muscle.

Authors: Leeuwenburgh, C  Gurley, CM  Strotman, BA  Dupont-Versteegden, EE 
Citation: Leeuwenburgh C, etal., Am J Physiol Regul Integr Comp Physiol. 2005 May;288(5):R1288-96. Epub 2005 Jan 13.
Pubmed: (View Article at PubMed) PMID:15650125
DOI: Full-text: DOI:10.1152/ajpregu.00576.2004

Muscle atrophy is associated with a loss of muscle fiber nuclei, most likely through apoptosis. We investigated age-related differences in the extent of apoptosis in soleus muscle of young (6 mo) and old (32 mo) male Fischer 344 x Brown Norway rats subjected to acute disuse atrophy induced by 14 days of hindlimb suspension (HS). HS-induced atrophy (reduction in muscle weight and cross-sectional area) was associated with loss of myofiber nuclei in soleus muscle of young, but not old, rats. This resulted in a significant decrease in the myonuclear domain (cross-sectional area per nucleus) in young and old rats, with changes being more pronounced in old animals. Levels of apoptosis (TdT-mediated dUTP nick end labeling and DNA fragmentation) were higher in soleus muscles of old control rats than young animals. Levels were significantly increased with HS in young and old rats, with the greatest changes in old animals. Caspase-3 activity in soleus muscle tended to be increased with age, but changes were not statistically significant (P=0.052). However, with HS, caspase-3 activity significantly increased in young, but not old, rats. Immunohistochemistry showed that the proapoptotic endonuclease G (EndoG, a mitochondrion-specific nuclease) was localized in the subsarcolemmal mitochondria in control muscles, and translocation to the nucleus occurred in old, but not young, control animals. There was no difference between EndoG total protein content in young and old control rats, but EndoG increased almost fivefold in soleus muscle of old, but not young, rats after HS. These results show that deregulation of myonuclear number occurs in old skeletal muscle and that the pathways involved in apoptosis are distinct in young and old muscles. Apoptosis in skeletal muscle is partly mediated by the subsarcolemmal mitochondria through EndoG translocation to the nucleus in response to HS.

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RGD Object Information
RGD ID: 9685359
Created: 2015-01-05
Species: All species
Last Modified: 2015-01-05
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.