Effect of chronic infusion of placental lactogen on ovine fetal growth in late gestation.
To test the hypothesis that placental lactogen (PL) is a humoral regulator of fetal growth, six singleton sheep fetuses received a continuous intravenous fusion of 1.2 mg/d of purified ovine PL (oPL) for 14 d, beginning on Day 122 of gestation. The plasma concentration of oPL was approximately four-fold higher in infused fetuses than in six control fetuses that received a continuous infusion of saline. The circulating insulin-like growth factor 1 (IGF-I) concentration was also significantly elevated in PL-infused fetuses (43.1 +/- 1.7 vs. 31.9 +/- 4.1 ng/ml; P < 0.05). Animals were slaughtered on Day 136, and the placenta and all major fetal tissues were dissected, weighed, and subsampled for chemical analysis. Fetal weight and crown-rump length were not significantly affected by treatment; however, the aggregate weight of the brain, liver, lungs, and heart tended to be larger (85.3 +/- 2.1 vs. 79.9 +/- 1.5 g/kg fetus; mean +/- SE, P = 0.07) and the thyroid gland was smaller (0.18 +/- 0.1 vs. 0.26 +/- 0.02 g/kg fetus; P < 0.05) in the PL-infused fetuses. The livers of the PL-infused fetuses had also accumulated additional glycogen (13.1 +/- 1.7 vs. 8.4 +/- 0.7 g; P < 0.05). In late gestation, PL within the fetal compartment increases fetal plasma IGF-I concentration and hepatic glycogen deposition and may affect the growth of several vital organs.
Schoknecht
P A
PA
Department of Animal Science, Cornell University, Ithaca, NY 14853-4801, USA.
McGuire
M A
MA
Cohick
W S
WS
Currie
W B
WB
Bell
A W
AW
D000818:Animals; D005314:Embryonic and Fetal Development / Q000187:drug effects*; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005865:Gestational Age; D006003:Glycogen / Q000378:metabolism; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008099:Liver / Q000196:embryology / Q000378:metabolism; D008297:Male; D010928:Placental Lactogen / Q000008:administration & dosage* / Q000097:blood / Q000494:pharmacology; D011247:Pregnancy; D012756:Sheep / Q000196:embryology*
D018971:Insulin-Like Growth Factor Binding Protein 2; D007334:Insulin-Like Growth Factor I; D006003:Glycogen; D010928:Placental Lactogen