MATERNAL GROWTH-HORMONE TREATMENT INCREASES PLACENTAL DIFFUSION CAPACITY BUT NOT FETAL OR PLACENTAL GROWTH IN SHEEP

We tested the hypothesis that chronic maternal GH administration would increase fetal substrate supply, increase maternal and fetal insulin- like growth factor I (IGF-I) concentrations, and therefore enhance gro wth in the late gestation fetal sheep. Eleven ewes received bovine GH 0.1 mg/kg twice daily for 10 days, whereas 10 control ewes received sa line. GH treatment increased placental capacity for simple diffusion ( P < 0.01), with a trend toward an increase in placental capacity for f acilitated diffusion (P = 0.07). GH treatment also lowered maternal an d fetal blood urea concentrations, and there was a trend toward increa sed fetal protein oxidation (P = 0.07). Maternal but not fetal IGF-I a nd insulin concentrations increased. Fetal and placental growth were n ot altered by GH treatment. Maternal and fetal metabolic status was si gnificantly affected by maternal food intake. We conclude that materna l GH treatment increases placental transport capacity, but that anabol ic effects in the mother may limit fetal substrate supply and therefor e prevent an increase in fetal growth.