Insulin-like growth factors and the developing and mature rat small intestine: Receptors and biological actions

G. P. Young, T. M. Taranto, H. A. Jonas, A. J. Cox, A. Hogg, G. A. Werther

Research output: Contribution to journalArticle

95 Citations (Scopus)

Abstract

To determine if insulin-like growth factor-I (IGF-I) or multiplication stimulating activity (MSA, rat IGF-II) might directly influence small intestinal epithelium, we studied the distribution of IGF binding sites during development of the rat intestine. Cell membranes from suckling rat mucosa bound 2-6 times as muchl25I-IGF-I and 3-5 times as much125I-MSA as did adult membranes. Isolated villus cells from suckling and adult rats specifically bound both IGFs. IGF-I binding tended to remain high during suckling, whereas MSA binding fell progressively from the early suckling period. Competitive displacement studies with insulin, IGF-I and MSA demonstrated the presence of type-I and type-II IGF receptors. In vitro autoradiography ofl25I-IGF-I binding sites in adult and suckling rat jejunum showed highest binding in the submucosa with extensions up into the lamina propria. Immunocytochemical localization of type-II receptors showed highest density in villus epithelium and vessel walls. Administration of MSA by oral and IGF-I by oral and parenteral routes (1 µg/day for 6 days) to suckling rats stimulated jejunal brush border enzymes, but not intestinal growth. Developmental changes in receptor density and effects on brush border enzymes suggest a specific role for IGFs in post-natal development of the rat intestine.
Original languageEnglish
Pages (from-to)240-252
Number of pages13
JournalDigestion
Volume46
Issue numbersupp 2
DOIs
Publication statusPublished - 1990
Externally publishedYes

Keywords

  • Brush border enzymes
  • Insulin-like growth factors
  • Intestinal mucosa
  • Milk
  • Receptors
  • Suckling

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