Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/31/2007
Publication Date: 7/3/2007
Citation: Vonnahme, K.A., Zhu, M.J., Borowicz, P.B., Geary, T.W., Hess, B.W., Reynolds, L.P., Caton, J.S., Means, W.J., Ford, S.P. 2007. Effect of early gestational undernutrition on angiogenic factor expression and vascularity in the bovine placentome. Journal of Animal Science doi 10:2527/jas.2006-805. Interpretive Summary: Maternal nutrient delivery during pregnancy has been shown to program the growth and development of the fetus, both during pregnancy and later into adult life. Data from this and other studies demonstrates that nutrition also programs the development of the placenta. Development of the placental vascular bed is imperative to support the growth and development of the fetus. While nutrient restriction from d 30 to d 125 increased placental mRNA expression of placental growth factor (PlGF) and its receptor (Flt), this increase did not alter the vascular architecture of the bovine placenta in the present study, placental function must have been altered as fetal weight was reduced. It appears that realimentation after 90 days of nutrient restriction in the cow is the stimulus for not only altering placental vascularity and development, but its function as well.
Technical Abstract: The effect of early gestation maternal undernutrition followed by realimentation on placentomal vascular growth and angiogenic factor expression was determined in multiparous beef cows bred to the same bull. Cows gestating only female fetuses (n=30) were fed in equal numbers to either meet NRC requirements (Control) or fed below NRC requirements to lose body weight from day 30 to 125 of gestation (nutrient restricted; NR). On day 125 of gestation, 10 Control and 10 NR cows were necropsied. The remaining NR cows (n = 5) were then fed to achieve a body condition score equal to their control contemporaries (n = 5) by day 220 of gestation. All cows were fed the control diet from day 220 until day 250 of gestation when the remaining Control and NR cows were necropsied. At necropsy, several placentomes were perfusion fixed via the caruncular and cotyledonary arteries to determine capillary vascular density. Cotyledonary and caruncular tissues were snap frozen in liquid nitrogen, and mRNA levels of vascular endothelial growth factor (VEGF) and its two specific receptors Flt and KDR, as well as placental growth factor (PlGF) were determined. Nutrient restriction from day 30 to 125 increased placental mRNA expression of PlGF and Flt; however, there was no alteration in vascularity. By day 250 of gestation, caruncles from NR cows had increased capillary surface density and decreased cotyledonary capillary area density, capillary number density and capillary surface density. Although NR had little effect on placental vascularity by day 125, placental function was reduced as reflected by the reduction in fetal weight. Upon realimentation, alterations in vascularity became apparent, along with an increased placental function, as fetal weights did not differ at day 250 of gestation.