Growth of artificially fed infant rats: Effect of supplementation with insulin-like growth factor I

Anthony F Philipps, Gary G. Anderson, Bohuslav Dvor̂ák, Catherine S. Williams, Mats Lake, Albert V. Lebouton, Otakar Koldovský

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


Insulin-like growth factor I (IGF-I), a potent mitogenic peptide, is present in considerable quantities in most mammalian milks, but its importance for the neonate is unknown. To test the hypothesis that milk- borne IGF-I is an important factor in the regulation of neonatal growth, as well as that of the gastrointestinal tract, rat pups were fed a rat milk substitute (RMS) devoid of growth factors via gastrostomy. These animals were compared with those given RMS supplemented with recombinant human IGF-I added at a concentration of 500 ng/ml. Animals given RMS + IGF-I gained more weight than controls, although skeletal growth as represented by elongation of the tail was no different. Animals fed RMS + IGF-I had increased brain and liver wet weights as well as increased liver and small intestine protein contents. Serum IGF-I concentrations in the IGF-I-supplemented group were more than twofold above RMS controls and were similar to dam-fed rat pups. Semiquantification of serum IGF-binding proteins (IGFBP) in these animals documented that in IGF-I-supplemented pups the amount of 38- to 40-kDa molecular mass IGFBP species was also greater than in RMS controls. The rate of migration of enterocytes from crypts in duodenum and proximal jejunum was greater in IGF-I-supplemented animals than in rats fed RMS alone. These studies suggest that milk-borne IGF-I is important in modulation of somatic and gastrointestinal tract growth in the neonatal rat.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number5 41-5
StatePublished - 1997
Externally publishedYes


  • Neonatal

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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