2004 Fiscal Year Final Research Report Summary
Relationship between myostatin and muscle enlargement during exercise and growth
| Project/Area Number |
15500456
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Sports science
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| Research Institution | Health Sciences University of Hokkaido |
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Principal Investigator |
YAMAGUCHI Akihiko Health Sciences University of Hokkaido, School of Dentistry, Associate Professor, 歯学部, 助教授 (50244869)
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| Project Period (FY) |
2003 – 2004
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| Keywords | growth / muscle enlargement / myostatin / exercise / hypophysectomy / insulin-like growth factor-I |
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| Research Abstract |
We examined myostatin mRNA expression in skeletal muscle of hypophysectomized and underfed rats during postnatal growth (experiment 1). Five-week old rats were divided into 4 groups : freely fed (NC), moderately underfed (MU), severely underfed (SU) and hypophysectomized (HX). The weights of soleus, plantaris and masseter muscles in NC were highest followed by those in MU. The lowest weights were in SU and HX. There were no differences in soleus muscle MHC isoforms between groups. Type I MHC in plantaris muscle in HX was increased significantly at the expense of type IIx. The neonatal MHC isoform in masseter muscle in HX was increased significantly at the expense of types IIx and IIb. Plantaris and masseter muscle myostatin mRNA levels in HX were significantly lower than those in SU, and levels in MU and SU were significantly higher than those in NC. We examined myostatin mRNA expression in plantaris muscle following hypophysectomy and compensatory overload (experiment 2). Nine-week old rats were divided into 4 groups: normal control (NC), normal overloaded (NOL), hypophysectomized control (HxC) and hypophysectomized overloaded (HxOL). The weights of plantaris muscle in NOL were significantly higher than those of NC 21 days after compensatory overload. The weights in HxOL were significantly higher than those of HxC. By hypophysectomy, the weights of plantaris muscle in HxC were significantly lower than those of NC. Myostatin mRNA levels of plantaris muscle in HxOL 3 and 21 days after compensatory overload were significantly lower than those in HxC. There were no differences in myostatin mRNA levels between NC and NOL. We conclude that suppressed muscle growth due to hypophysectomy and underfeeding as well as muscle enlargement due to compensatory overload were associated with the expression of myostatin.
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