Recipient Organization
TEXAS A&M UNIVERSITY
750 AGRONOMY RD STE 2701
COLLEGE STATION,TX 77843-0001
Performing Department
Animal Science
Non Technical Summary
Low birth weight is strongly correlated with risk of death or ill-thrift at birth in all mammalian livestock species, including sheep. This death loss decreases the efficiency of meat production for human consumption and contributes to food insecurity throughout the world. Therefore, understanding simple, cost effective means to promote fetal growth through improved placental development and function have the potential to improve the efficiency and sustainability of meat production from sheep and other ruminant livestock species by reducing perinatal death losses, which may exceed 20%. In preliminary studies we have identified two potential nutraceutical products that have the potential to stimulate placental development and function. Our project aims to determine if either or both of our nutraceutical products (citrulline or putrescine) improves fetal growth and development in lambs. We will then carry out additional in-depth studies to determine the mechanism(s) by which these products improved fetal growth, if that is an observed result. If either of these products is shown to improve fetal growth of lambs we would expect that these findings would be translated to production agriculture through the incorporation of these nutraceuticals into feedstuffs formulated for and fed to gestating ewes.
Animal Health Component
25%
Research Effort Categories
Basic
75%
Applied
25%
Developmental
0%
Goals / Objectives
The long-term goals of the proposed project are to: (1) identify and examine the nutritionally-influenced cellular and molecular pathways regulating interactions between the conceptus and its uterine environment to ensure optimal fetal development; and (2) use this fundamental knowledge to improve reproductive efficiency and profitability of animal production enterprises. Although it is established that maternal nutrition impacts fetal growth, the physiological pathways that underlie these processes in the uterus and placenta, and how they interact, are not broadly understood. Knowledge in this area is important because in the face of changing climates, understanding the physiological relationship between maternal nutrition and subsequent uterine environment, placental function, and fetal development will be necessary to enhance production efficiency to meet the demands for food animal protein to feed a growing population.Our working hypothesis is that increased transport and/or metabolism of polyamines, and their amino acid precursors, by the placenta, promotes placental angiogenesis and growth allowing for increases in blood flow and nutrient transport as a means to prevent IUGR. To begin testing the hypothesis and elucidate the physiological mechanisms underlying placental growth and function, two specific aims are proposed, using complementary in vitro and in vivo experiments in the sheep.Specific Aim 1: Determine the mechanism(s) by which polyamines and their precursors regulate placental angiogenesis The objective of specific aim 1 is to utilize a novel 3D invasion assay that mimics angiogenesis to test the hypothesis that putrescine and spermine can independently promote angiogenesis in ovine fetoplacental artery endothelial cells (oFPAEC) through unique signaling pathways.Specific Aim 2: Elucidate angiogenic and placental histoarchitectural responses to nutraceutical stimulation of placental development and functionThe objective of specific aim 2 will be to test two independent, but related hypotheses, each supported by a strong body of published and preliminary data.Hypothesis 1: Maternal putrescine supplementation to NR ewes will promote placental growth and angiogenesis leading to increased nutrient transport and fetal growth.Hypothesis 2: Maternal citrulline supplementation to NR ewes will increase fetal growth by increasing arginine availability and activation of the polyamine and nitric oxide signaling pathways.
Project Methods
To test the two specific aims of the project we will conduct the following experiments. The objective of specific aim 1 is to determine the mechanism(s) by which polyamines and their precursors regulate placental angiogenesis. This objective will be conducted using a novel 3D invasion assay using an ovine fetal umbilical cell line. These in vitro molecular biology studies will determine which select nutrients and their metabolic products promote placental angiogenesis. For those that promote angiogenesis we will then determine the cellular signaling pathways that regulate this process. Finally we will determine the gene networks that are upregulated within the endothelial cells by these nutrients to promote placental angiogenesis. The objective of specific aim 2 is to elucidate angiogenic and placental histoarchitectural responses to nutraceutical stimulation of placental development and function. This objective will be conducted using an intricately designed in vivo animal experiment using sheep as the animal model. To control for factors known to influence rates of fetal growth we will perform these experiments on pregnant sheep made by embryo transfer of a single high quality embryo into the surrogate dam. This will eliminate the influence of fetal number on the experimental outcomes. All embryos will be generated by a single sire to reduce genetic variation. Finally, all pregnancies will be generated within a one week period to reduce the influence of environmental conditions on the experimental outcomes. Pregnant ewes will be blocked by maternal weight and assigned to one of two dietary intake levels (50% or 100% of National Research Council guidelines) and one of three nutraceutical supplements, (alanine as an isonitrogenous control, citrulline, or putrescine). The overall result is a 2 x 3 factorial design. All dietary and nutraceutical treatments will be applied beginning on Day 28 of pregnancy when the placenta is in its early stages of formation. A single placentome will be surgically removed on day 50 of pregnancy to determine early changes in placental development in response to diet and/or nutraceutical supplement. On day 124 all fetal and placental tissues will be collected at necropsy. At this time we will assess placental nutrient transport capacity and mechanisms, placental histoarchitectural development, and placental gene and protein expression based on findings from specific aim 1. All data will be appropriately analyzed using appropriate statistical software such as SAS or PRISM. A P value of <0.05 will be accepted as a significant effect of treatment. At the conclusion of this work results will be submitted for publication in peer reviewed journals for dissemination of findings to the scientific community. In addition, data will be presented at appropriate scientific meetings to inform the scientific community of our research findings.