Maternal insulin-like growth factor-I infusion alters feto-placental carbohydrate and protein metabolism in pregnant sheep.
Insulin-like growth factor-I (IGF-I) in the maternal circulation may have a role in the regulation of placental function and fetal growth, but its mechanisms of action are not known. We studied the effects of maternal IGF-I infusion (30 micrograms/kg.h for 4 h) in eight chronically catheterized pregnant sheep. IGF-I infusion caused an increase in fetal blood glucose concentrations, but no change in placental or fetal glucose uptake. Maternal plasma insulin concentrations fell. Placental lactate production increased by 56%, with most of this lactate taken up by the fetus. Maternal and fetal blood amino nitrogen concentrations fell, but fetal protein oxidation was unchanged. IGF-I infusion did not change feto-placental oxygenation, placental blood flow, or placental transfer by simple or facilitated diffusion. The metabolic effects of maternal IGF-I infusion in part oppose those of fetal IGF-I. We hypothesize that the balance of maternal and fetal IGF-I concentrations contributes to the regulation of substrate distribution between mother, placenta and fetus, and may thus mediate the nutritional regulation of fetal growth.
Liu
L
L
Research Center for Developmental Medicine and Biology, University of Auckland, New Zealand.
Harding
J E
JE
Evans
P C
PC
Gluckman
P D
PD
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D050260:Carbohydrate Metabolism; D005260:Female; D005312:Fetal Blood; D005333:Fetus / Q000378:metabolism*; D005865:Gestational Age; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology*; D007773:Lactates / Q000378:metabolism; D008431:Maternal-Fetal Exchange / Q000187:drug effects*; D010920:Placenta / Q000098:blood supply; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D012039:Regional Blood Flow
D001786:Blood Glucose; D007328:Insulin; D007773:Lactates; D011506:Proteins; D007334:Insulin-Like Growth Factor I