Maternal Nutrient Restriction Upregulates Growth Signaling Pathways in the Cotyledonary Artery of Cow Placentomes

This study evaluated the role of MAPK/ERK1/2 and/or PI3-K/Akt signaling pathways in modulating bovine placentomal vascularity in response to maternal nutrient restriction. Beef cows were randomly assigned to control fed (Control, n = 15, 100% of requirements) or nutrient restricted (NR, n = 15, 50% requirements) diets from day 30 to day 125 of gestation. Ten cows from each dietary group were necropsied on day 125 (∼45% gestation), and the remaining cows in each diet group were then fed control diets and necropsied on day 250 (∼90% gestation). At day 125 of gestation, NR cows exhibited increased (P = 0.06) COT vascularity, improved (P < 0.05) placentome efficiency (fetal weight/placentomal weight), and increased (P < 0.05) phosphorylated Akt and ERK1/2 in COT arteries compared to Control cows. By day 250, however, treatment differences in COT vascularity and phosphorylated Akt and ERK1/2 in COT arteries were lost. On both gestational days, no treatment difference was observed in the levels of phosphorylated Akt or ERK1/2 in CAR arteries. CAR vascularity was similar across treatment on day 125, but tended to be greater (P < 0.10) in NR than Control cows on day 250. These data suggest that conceptuses react to an early gestational nutrient restriction by up-regulating COT growth signaling pathways associated with angiogenesis, and that these compensations do not persist to term.