Nutrient restriction (NR) has the potential to negatively impact birthweight, an indicator of neonatal survival and lifelong health. Those fetuses are termed as small for gestational age (SGA). Interestingly, there is a spectral phenotype of fetal growth rates in response to NR associated with changes in placental development, nutrient and waste transport, and lipid metabolism. A sheep model with a maternal diet, starting at Day 35, of 100% National Research Council (NRC) nutrient requirements (n = 8) or 50% NRC (n = 28) was used to assess alterations in fetuses designated NR SGA (n = 7) or NR NonSGA (n = 7) based on fetal weight at Day 135 of pregnancy. Allantoic fluid concentrations of triglycerides were greater in NR SGA fetuses than 100% NRC and NR NonSGA fetuses at Day 70 (P < 0.05). There was a negative correlation between allantoic fluid concentrations of triglycerides (R² = 0.207) and bile acids (R² = 0.179) on Day 70 and fetal weight at Day 135 for NR ewes (P < 0.05). Bile acids were more abundant in maternal and fetal blood for NR SGA compared to 100% NRC and NR NonSGA ewes (P < 0.05). Maternal blood concentrations of NEFAs increased in late pregnancy in NR NonSGA compared to NR SGA ewes (P < 0.05). Protein expression of fatty acid transporter SLC27A6 localized to placentomal maternal and fetal epithelia and decreased in Day 70 NR SGA compared to 100% NRC and NR NonSGA placentomes (P < 0.05). These results identify novel factors associated with an ability of placentae and fetuses in NR NonSGA ewes to adapt to, and overcome, nutritional hardship during pregnancy.

中文翻译：

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小于胎龄胎儿的母羊母羊、胎盘和胎儿组织中的脂质代谢发生改变

营养限制 (NR) 有可能对出生体重产生负面影响，出生体重是新生儿存活率和终生健康的指标。这些胎儿被称为小于胎龄 (SGA)。有趣的是，胎儿生长速率的光谱表型响应与胎盘发育、营养和废物运输以及脂质代谢的变化相关的 NR。从第 35 天开始，母羊饮食为 100% 国家研究委员会 (NRC) 营养需求 ( n  = 8) 或 50% NRC ( n  = 28)的绵羊模型用于评估指定为 NR SGA ( n  = 7) 或 NR NonSGA ( n = 7) 基于怀孕第 135 天的胎儿体重。在第 70 天，NR SGA 胎儿尿囊液的甘油三酯浓度高于 100% NRC 和 NR NonSGA 胎儿（P  < 0.05）。 NR 母羊第 70 天的尿囊液甘油三酯 ( R ²  = 0.207) 和胆汁酸 ( R ² = 0.179)浓度与第 135 天的胎儿体重呈负相关( P  < 0.05)。与 100% NRC 和 NR NonSGA 母羊相比，NR SGA 母羊和胎儿血液中的胆汁酸含量更高 ( P  < 0.05)。与 NR SGA 母羊相比，NR NonSGA 母羊的母体血液中 NEFAs 浓度在妊娠晚期增加（P < 0.05)。与 100% NRC 和 NR NonSGA 胎盘组相比，脂肪酸转运蛋白 SLC27A6 的蛋白质表达定位于胎盘母体和胎儿上皮细胞，并在第 70 天 NR SGA 中降低（P  < 0.05）。这些结果确定了与 NR NonSGA 母羊胎盘和胎儿适应和克服怀孕期间营养困难的能力相关的新因素。