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Chronic exercise accelerates the degeneration–regeneration cycle and downregulates insulin‐like growth factor‐1 in muscle of mdx mice
Author(s) -
Okano T.,
Yoshida K.,
Nakamura A.,
Sasazawa F.,
Oide T.,
Takeda S.,
Ikeda S.
Publication year - 2005
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.20351
Subject(s) - regeneration (biology) , degeneration (medical) , insulin like growth factor , medicine , growth factor , endocrinology , mdx mouse , skeletal muscle , biology , microbiology and biotechnology , pathology , receptor , dystrophin
The aim of this study was to examine the effects of chronic running exercise on degenerative–regenerative processes in the hindlimb muscles of dystrophin‐deficient mdx mice. The number of large‐sized degenerative–regenerative groups (DRGs) was markedly decreased, whereas that of small‐sized DRGs was unchanged by exercise. Expression of insulin‐like growth factor‐1 ( Igf1 ), as well as a myogenic factor MyoD ( Myod1 ), was downregulated in mdx muscles by exercise. The downregulation of Igf1 may well correlate with the decrease in the population of early regenerating fibers, which existed predominantly in DRGs, because IGF‐1 was mainly localized in these fibers. Our data indicate that chronic exercise may accelerate the active cycle of degeneration–regeneration in mdx skeletal muscles. This means that mdx skeletal muscles can temporarily cope with work‐induced injury by enhancing muscle regeneration and repair, but we speculate that an early decline of IGF‐1 will accelerate age‐dependent muscle wasting and weakness in the later stage of life in mdx mice. Muscle Nerve, 2005