Effects of eccentric treadmill running on mouse soleus: degeneration/regeneration studied with Myf-5 and MyoD probes.
OBJECTIVE
The aim of this report is to show that eccentric exercise under well-controlled conditions is an alternative model, to chemical and mechanical analyses, and analyse the process of degeneration/regeneration in mouse soleus.


METHODS
For this, mice were submitted to a single bout of eccentric exercise on a treadmill down a 14 degrees decline for 150 min and the soleus muscle was analysed at different times following exercise by histology and in situ hybridization in comparison with cardiotoxin-injured muscles.


RESULTS
We analyse the regenerative process by detection of the accumulation of transcripts coding for the two myogenic regulatory factors, Myf-5 and MyoD, which are good markers of the activated satellite cells. From 24 h post-exercise (P-E), clusters of mononucleated Myf-5/MyoD-positive cells were detected. Their number increased up to 96 h P-E when young MyoD-positive myotubes with central nuclei began to appear. From 96 to 168 h P-E the number of myotubes increased, about 10-fold, the new myotubes representing 58% of the muscle cells (168 h P-E).


CONCLUSIONS
These results show that this protocol of eccentric exercise is able to induce a drastic degeneration/regeneration process in the soleus muscle. This offers the opportunity to perform biochemical and molecular analyses of a process of regeneration without muscle environment defects. The advantages of this model are discussed in the context of fundamental and therapeutical perspectives.
Armand
A-S
AS
Biologie du Développement et de la Différenciation Neuromusculaire, LNRS UMR 7060 CNRS, Université René Descartes, Paris Cedex, France.
Launay
T
T
Gaspera
B Della
BD
Charbonnier
F
F
Gallien
C L
CL
Chanoine
C
C
D000818:Animals; D004179:Cobra Cardiotoxin Proteins; D004268:DNA-Binding Proteins; D004195:Disease Models, Animal; D005260:Female; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000473:pathology / Q000502:physiology; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D017570:MyoD Protein / Q000378:metabolism; D051787:Myogenic Regulatory Factor 5; D009336:Necrosis; D005082:Physical Exertion / Q000502:physiology*; D012038:Regeneration; D015534:Trans-Activators
D004179:Cobra Cardiotoxin Proteins; D004268:DNA-Binding Proteins; D009124:Muscle Proteins; C497418:Myf5 protein, mouse; D017570:MyoD Protein; D051787:Myogenic Regulatory Factor 5; D015534:Trans-Activators