Effect of training and growth hormone suppression on insulin-like growth factor I mRNA in young rats

S. Zanconato, D. Y. Moromisato, M. Y. Moromisato, J. Woods, J. A. Brasel, D. Leroith, C. T. Roberts, D. M. Cooper

Research output: Contribution to journalArticlepeer-review

72 Scopus citations


The growth hormone (GH)-insulin-like growth factor I (IGF-I) axis plays a role in the adaptation to exercise training, but IGF-I gene expression in response to exercise training and GH suppression has not been studied. Twenty female rats underwent a 4-wk treadmill training program begun in the prepubertal period (day 14 of life). In 10 of the training rats, GH production was suppressed by anti-GH-releasing hormone antibodies (GH suppressed). IGF-I mRNA and protein levels were measured in liver and hindlimb skeletal muscle. GH suppression reduced IGF-I mRNA expression in the liver to a much greater extent than in the muscle. In the GH control rats, training induced significant increases in hepatic exon 1-derived IGF-I mRNA (mean increase 30%; P < 0.05) and muscle exon 2-derived mRNA (mean increase 35%; P < 0.05). In the GH-suppressed rats, only muscle exon 1-derived transcripts were significantly increased by training (55%; P < 0.05) and this was associated with a significant increase in muscle IGF-I protein levels (P < 0.05). We speculate that the anabolic response to training may involve both GH-dependent increases in IGF-I mRNA in the liver and GH-independent increases in the muscle.

Original languageEnglish (US)
Pages (from-to)2204-2209
Number of pages6
JournalJournal of Applied Physiology
Issue number5
StatePublished - 1994
Externally publishedYes


  • hindlimb muscle
  • insulin-like growth factor I protein level
  • liver

ASJC Scopus subject areas

  • General Medicine


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