Effect of insulin‐like growth factor‐I during the early postnatal period in intrauterine growth‐restricted rats

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Insulin‐like growth factor‐I (IGF‐I) is essential for perinatal growth and development; low serum IGF‐I has been observed during intrauterine growth restriction (IUGR). We investigated the effects of recombinant human (rh) IGF‐I in IUGR rats during the early postnatal period.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Intrauterine growth restriction was induced by bilateral uterine artery ligation in pregnant rats. IUGR pups were divided into two groups injected daily with rhIGF‐I (2 mg/kg; IUGR/IGF‐I, n = 16) or saline (IUGR/physiologic saline solution (PSS), n = 16) from postnatal day (PND) 7 to 13. Maternal sham‐operated pups injected with saline were used as controls (control, n = 16). Serum IGF‐I and IGF binding proteins (IGFBP) 3 and 5 were measured on PND25. The expression of <jats:italic>Igf‐i</jats:italic>, IGF‐I receptor (<jats:italic>Igf‐ir</jats:italic>), <jats:italic>Igfbp3</jats:italic>, and <jats:italic>5</jats:italic> mRNA in the liver and brain was measured using real‐time polymerase chain reaction on PND25. Immunohistochemical staining of the liver for IGF expression was performed.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Mean bodyweight on PND3 and PND25 in the IUGR pups (IUGR/IGF‐I and IUGR/PSS) was significantly lower than that of the control pups. Serum IGF‐I and hepatic <jats:italic>Igf‐ir</jats:italic> mRNA in the IUGR pups were significantly lower than those in the control pups. In the IUGR/IGF‐I group, hepatic <jats:italic>Igfbp3</jats:italic> mRNA and liver immunohistochemical staining were increased. In the IUGR/PSS and control pups, there were no significant differences between these two groups in serum IGFBP3 and IGFBP5, hepatic <jats:italic>Igf‐i</jats:italic> and <jats:italic>Igfbp‐5</jats:italic> mRNA, or brain <jats:italic>Igf</jats:italic> mRNA.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>No benefits on body and brain weight gain but an effective increase in hepatic IGFBP‐3 was observed after treatment with 2 mg/kg rhIGF‐I during the early postnatal period.</jats:p></jats:sec>