Control of growth by the somatropic axis: growth hormone and the insulin-like growth factors have related and independent roles

Annu Rev Physiol. 2001;63:141-64. doi: 10.1146/annurev.physiol.63.1.141.


The traditionally accepted theory has been that most of the biological effects of growth hormone (GH) are mediated by circulating (endocrine) insulin-like growth factor-I (IGF-I). This dogma was modified when it was discovered that most tissues express IGF-I that can act via an autocrine/paracrine fashion. In addition, both GH and IGF-I had independent effects on various target tissues. Using tissue-specific gene deletion of IGF-I in the liver, it has been shown that circulating IGF-I is predominantly liver-derived but is not essential for normal postnatal growth. Therefore, it is proposed that non-hepatic tissue-derived IGF-I may be sufficient for growth and development. Thus the original somatomedin hypothesis has undergone further modifications.

Publication types

  • Review

MeSH terms

  • Animals
  • Cell Division / physiology
  • Growth Hormone / genetics*
  • Growth Hormone / metabolism*
  • Insulin-Like Growth Factor I / genetics*
  • Insulin-Like Growth Factor I / metabolism*
  • Mice
  • Mice, Knockout


  • Insulin-Like Growth Factor I
  • Growth Hormone