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Muscle satellite cells are activated after exercise to exhaustion in T horoughbred horses
Author(s) -
Kawai M.,
Aida H.,
Hiraga A.,
Miyata H.
Publication year - 2013
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.12010
Subject(s) - proliferating cell nuclear antigen , muscle hypertrophy , myogenin , medicine , hepatocyte growth factor , endocrinology , biology , myocyte , myogenesis , immunohistochemistry , receptor
Summary Reasons for performing study Although satellite cells are well known as muscle stem cells capable of adding myonuclei during muscle repair and hypertrophy, the response of satellite cells in horse muscles to a run to exhaustion is still unknown. Objectives To investigate the time course of satellite cell activation in T horoughbred horse muscle after running to exhaustion. We hypothesised that this type of intense exercise would induce satellite cell activation in skeletal muscle similar to a resistance exercise. Methods Nine de‐trained T horoughbred horses (6 geldings and 3 mares) aged 3–6 years were studied. Biopsy samples were taken from the gluteus medius muscle of the horses before and 1 min, 3 h, 1 day, 3 days, 1 week and 2 weeks after a treadmill run to exhaustion. The numbers of satellite cells for each fibre type were determined by using immunofluorescence staining. Total RNA was extracted from these samples, and the expressions of interleukin ( IL )‐6, paired box transcriptional factor ( P ax) 7, myogenic differentiation 1 ( M yo D ), myogenin, proliferating cell nuclear antigen ( PCNA ), insulin‐like growth factor ( IGF )‐ I and hepatocyte growth factor ( HGF ) m RNA were analysed using real‐time reverse transcription‐ PCR . Results The numbers of satellite cells were significantly increased in type I and II a fibres at 1 week and in type II a/x fibre at 2 weeks post exercise. The expression of IL ‐6 m RNA increased significantly by 3 h post exercise. The expression of PCNA m RNA also increased by 1 day after running, indicating that running can initiate satellite cell proliferation. The expression of P ax7, M yo D , myogenin, IGF ‐ I and HGF m RNA peaked at 1 week post exercise. Conclusion Satellite cell activation and proliferation could be enhanced after a run to exhaustion without detectable injury as assessed by the histochemical analysis. Understanding the response of satellite cell activation to running exercise provides fundamental information about the skeletal muscle adaptation in T horoughbred horses.