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Modulation of myostatin expression during modified muscle use
M Wehling1, B Cai, J G Tidball
1Department of Physiological Science, University of California, Los Angeles, Los Angeles, California 90095-1527, USA.
Summary
Myostatin negatively regulates muscle mass. In differentiated muscle, unloading increases myostatin, but this increase alone doesn't cause muscle loss. Targeted loading prevents atrophy despite elevated myostatin.
Area of Science:
- Muscle physiology
- Molecular biology
- Skeletal muscle research
Background:
- Myostatin is a known negative regulator of muscle mass during development and growth.
- The role of myostatin in fully differentiated skeletal muscle under altered loading conditions requires further investigation.
Purpose of the Study:
- To investigate the role of myostatin in differentiated skeletal muscle experiencing unloading and reloading.
- To determine if myostatin expression changes inversely with muscle mass in response to modified loading.
Main Methods:
- Induction of muscle atrophy in rat hind limb muscles via unloading for 10 days.
- Measurement of plantaris muscle mass, myostatin mRNA, and myostatin protein levels.
- Immunohistochemical analysis to assess myostatin concentration at myotendinous junctions.
- Evaluation of muscle mass and myostatin levels during reloading and during unloading with intermittent daily loading.
Main Results:
- Unloading induced significant muscle atrophy (16% decrease in plantaris mass) accompanied by increased myostatin mRNA (110%) and protein (37%).
- Myostatin concentration increased at myotendinous junctions during unloading.
- Muscle mass and myostatin levels returned to control values after reloading.
- Daily intermittent loading prevented significant muscle mass loss, though myostatin mRNA levels remained elevated (55% increase).
Conclusions:
- Myostatin expression is inversely related to muscle mass changes in differentiated skeletal muscle under modified loading.
- Increased myostatin expression alone is insufficient to cause muscle mass loss.
- Muscle unloading leads to increased myostatin, but this increase does not necessarily equate to muscle atrophy if loading is maintained intermittently.
Keywords:
Non-programmatic