Maternal insulin-like growth factor-II promotes placental functional development via the type 2 IGF receptor in the guinea pig.

Abstract

In guinea pigs, maternal insulin-like growth factor (IGF) infusion in early-pregnancy enhances placental transport near-term, increasing fetal growth and survival. The effects of IGF-II, but not IGF-I, appear due to enhanced placental labyrinthine (exchange) development. To determine if the type-2 IGF receptor (IGF2R) mediates these distinct actions of exogenous IGF-II in the mother, we compared the impact of IGF-II with an IGF-II analogue, Leu(27)-IGF-II, which only binds the IGF2R. IGF-II, Leu(27)-IGF-II (1mg/kg per day.sc) or vehicle were infused from days 20-38 of pregnancy (term = 67 days) and placental structure and uptake and transfer of [(3)H]-methyl-D-glucose (MG) and [(14)C]-amino-isobutyric acid (AIB) and fetal growth and plasma metabolites, were measured on day 62. Both IGF-II and Leu(27)-IGF-II increased the volume of placental labyrinth, trophoblast and maternal blood space within the labyrinth and total surface area of trophoblast for exchange, compared to vehicle. Leu(27)-IGF-II also reduced the barrier to diffusion (trophoblast thickness) compared to vehicle and IGF-II. Both IGF-II and Leu(27)-IGF-II increased fetal plasma amino acid concentrations and placental transfer of MG to the fetus compared to vehicle, with Leu(27)-IGF-II also increasing AIB transport compared with vehicle and IGF-II. In addition, Leu(27)-IGF-II increased fetal weight compared to vehicle. In conclusion, maternal treatment with IGF-II or Leu(27)-IGF-II in early gestation, induce similar placental and fetal outcomes near term. This suggests that maternal IGF-II in early gestation acts in part via the IGF2R to persistently enhance placental functional development and nutrient delivery and promote fetal growth.

• Authors: A N Sferruzzi-Perri, J A Owens, P Standen, C T Roberts
• Journal: Placenta (Placenta) Vol. 29 Issue 4 Pg. 347-55 (Apr 2008) ISSN: 0143-4004 [Print] Netherlands
• PMID: 18339421 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Amino Acids
• Aminoisobutyric Acids
• Receptor, IGF Type 2
• 3-O-Methylglucose
• Insulin-Like Growth Factor II

Topics

• 3-O-Methylglucose (blood, metabolism)
• Adipose Tissue (drug effects, metabolism)
• Amino Acids (blood)
• Aminoisobutyric Acids (blood, metabolism)
• Animals
• Biological Transport (drug effects)
• Blood Vessels (anatomy & histology, drug effects)
• Body Composition (drug effects)
• Body Weight (drug effects)
• Female
• Fetal Weight (drug effects)
• Fetus (blood supply, drug effects, metabolism)
• Guinea Pigs
• Insulin-Like Growth Factor II (analogs & derivatives, pharmacology)
• Litter Size (drug effects)
• Maternal-Fetal Exchange (drug effects)
• Organ Size (drug effects)
• Placenta (anatomy & histology, drug effects, metabolism)
• Placentation
• Pregnancy
• Receptor, IGF Type 2 (physiology)
• Trophoblasts (drug effects)