Modulation of IGF mRNA abundance during muscle denervation atrophy

Susan M. Czerwinski, Jan Novakofski, Peter J. Bechtel

Research output: Contribution to journalArticle

Abstract

Changes in skeletal muscle activity cause dramatic alterations in muscle mass. Increased load on a muscle (synergistic overload) results in muscle hypertrophy. During hypertrophy, skeletal muscle concentrations of insulin-like growth factors (IGF-I and IGF-II) mRNAs increase. To clarify the role of IGFs in regulating muscle mass, this study examined whether IGF-I and -II mRNA levels were altered during decreased muscle activity (denervation). Gastrocne-mius weights decreased 4.2%, 7.7%, 18.1%, 27.7%, 35.1%, 45.0%, and 60.3% at 2, 3, 5, 7, 10, 12, and 17 d following denervation, respectively. Muscle DNA content remained constant throughout the first 12 d after surgery, but increased above control levels at day 17. During the first week after surgery, gastrocnemius IGF-II mRNA remained constant. However, IGF-II mRNA abundance was 2.5-fold greater than controls by 10 d of denervation, 3-fold by 12 d, and 6.8-fold by 17 d. On the other hand, IGF-I mRNA levels were not affected by denervation. In conclusion, although increased muscle activity results in a change of IGF-I mRNA expression, decreased muscle activity has no effect on IGF-I mRNA expression. In contrast, IGF-II mRNA levels increase with long-term denervation as well as with increased muscle activity. This study suggests that muscle activity may not be the only factor affecting IGF-I and -II expression.

Original languageEnglish (US)
Pages (from-to)1005-1008
Number of pages4
JournalMedicine and Science in Sports and Exercise
Volume25
Issue number9
DOIs
StatePublished - Sep 1993

Keywords

  • Dna
  • Female rats
  • Gastrocnemius
  • Igf

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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