Insulin-like growth factor-I stimulates erythropoiesis when administered enterally

Pamela J. Kling, K. Muy Taing, Bohuslav Dvorak, Suann S. Woodward, Anthony F Philipps

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Background: Insulin-like growth factors I and II (IGF-I and IGF-II) are potent growth factors involved in development. IGF-I stimulates proliferation of erythropoietic progenitors and parenteral IGF-I administration stimulates in vivo erythropoiesis in animals. IGF-I and IGF-II are both present in mammalian milks and when milk-borne, are resistant to neonatal gastrointestinal degradation. Whether milk-borne IGF-I or IGF-II regulates neonatal erythropoiesis in not known. We hypothesized that physiological doses of enteral IGFs stimulate erythropoiesis in suckling rats. Methods: Eight day-old Sprague Dawley rats were artificially fed for 4 days with rat milk substitute (RMS) or RMS supplemented with physiological levels of IGF-I or IGF-II. Rats fed IGF-I and IGF-II were compared to control RMS. Blood and marrow were collected; measures of red cell mass, measures of erythropoietic stimulus, and indices of iron status were measured. Results: Rats fed IGF-I had higher hemoglobin (Hb) levels (100 ± 10 g/l), compared to those fed RMS (94 ± 9) or IGF-II (91 ± 6), p < 0.001. After IGF-I supplementation, red blood cell counts (RBC) (p < 0.04) and hematocrits (p < 0.002) were also higher. Plasma erythropoietin (Epo) levels, reticulocytes, plasma iron and erythrocyte iron incorporation were similar. Conclusion: Intact enteral IGF-I reaches distal erythropoietic tissue resulting in greater red cell mass, but not by increasing plasma Epo levels or by altering cellular iron transport.

Original languageEnglish (US)
Pages (from-to)218-223
Number of pages6
JournalGrowth Factors
Issue number3
StatePublished - Sep 2006


  • Erythropoiesis
  • Erythropoietin
  • Insulin-like growth factors
  • Transferrin receptor
  • Zinc protoporphyrin/heme ratio

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Endocrinology
  • Cell Biology


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