Impact of treadmill locomotor training on skeletal muscle IGF1 and myogenic regulatory factors in spinal cord injured rats.
The objective of this study was to determine the impact of treadmill locomotor training on the expression of insulin-like growth factor I (IGF1) and changes in myogenic regulatory factors (MRFs) in rat soleus muscle following spinal cord injury (SCI). Moderate, midthoracic (T(8)) contusion SCIs were produced using a NYU (New York University) impactor. Animals were randomly assigned to treadmill training or untrained groups. Rats in the training group were trained starting at 1 week after SCI, for either 3 bouts of 20 min over 1.5 days or 10 bouts over 5 days. Five days of treadmill training completely prevented the decrease in soleus fiber size resulting from SCI. In addition, treadmill training triggered increases in IGF1, MGF and IGFBP4 mRNA expression, and a concurrent reduction of IGFBP5 mRNA in skeletal muscle. Locomotor training also caused an increase in markers of muscle regeneration, including small muscle fibers expressing embryonic myosin and Pax7 positive nuclei and increased expression of the MRFs, myogenin and MyoD. We concluded that treadmill locomotor training ameliorated muscle atrophy in moderate contusion SCI rats. Training-induced muscle regeneration and fiber hypertrophy following SCI was associated with an increase in IGF1, an increase in Pax7 positive nuclei, and upregulation of MRFs.
Liu
Min
M
Department of Physical Therapy, University of Florida, P.O. Box 100154, Rm 1142 PHHP Bldg, Gainesville, FL 32610, USA.
Stevens-Lapsley
Jennifer E
JE
Jayaraman
Arun
A
Ye
Fan
F
Conover
Christine
C
Walter
Glenn A
GA
Bose
Prodip
P
Thompson
Floyd J
FJ
Borst
Stephen E
SE
Vandenborne
Krista
K
D000818:Animals; D004195:Disease Models, Animal; D005081:Exercise Therapy; D005260:Female; D006984:Hypertrophy; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D009043:Motor Activity; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D009133:Muscular Atrophy / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000378:metabolism*; D051761:Paired Box Transcription Factors / Q000378:metabolism; D010805:Physical Conditioning, Animal; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D012038:Regeneration; D013119:Spinal Cord Injuries / Q000150:complications / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D013997:Time Factors
D018969:Insulin-Like Growth Factor Binding Proteins; D018006:Myogenic Regulatory Factors; C530821:PAX7 protein, rat; D051761:Paired Box Transcription Factors; D012333:RNA, Messenger; C548904:insulin-like growth factor-1, rat; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1