Rabaglino Maria Belen, Sánchez José María, Mc Donald Michael, Crowe Mark A, O'Callaghan Elena, Lonergan Pat
School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Ctr. de la Coruña km 5.9, 28040, Madrid, Spain.
Theriogenology. 2023 Apr 1;200:25-32. doi: 10.1016/j.theriogenology.2023.01.020. Epub 2023 Jan 28.
Elevated circulating progesterone (P4) concentrations in the first week after conception have been associated with accelerated post-hatching conceptus elongation. However, the consequences, if any, on the development of the fetus are unknown. The objective of this study was to determine the relationship between early circulating P4 and fetal and placental morphometric characteristics at 42 days of gestation. A previously validated model of asynchronous embryo transfer (ET), known to alter uterine exposure to P4, was used in 107 heifers divided in two replicates (replicate 1: n = 51, replicate 2: n = 56). Heifers were randomly assigned to one of the two following groups: those receiving a Day 7 embryo on Day 7 of the cycle (synchronous; ET_D7, n = 49) and those transferred a Day 7 embryo on Day 9 of the cycle (asynchronous; ET_D9, n = 58). The synchronization protocol was started two days earlier for heifers in the ET_D9 group such that ET was done on the same day for both groups. P4 concentrations were determined from Day 3 after estrus to the day of ET. Pregnant heifers were slaughtered at Day 42 of gestation for fetal and placental morphometric measurements. The effects of the group, replicate, fetal sex, and interactions between these variables on fetal and placental characteristics were determined by ANOVA, while Pearson correlation was employed to assess the linear relationship between P4 concentrations two days before and on the day of ET on the fetal parameters. The uteri of heifers in the ET_D9 group were exposed to higher concentrations (P < 0.0001) of P4 from four days before ET, than heifers in the ET_D7 group. Both group and fetal sex variables impacted on fetal crown-rump length (CRL) (group: P < 0.0001, sex: P = 0.001) and fetal weight (group: P = 0.006, sex: P = 0.003). Fetal sex influenced the amniotic sac area (P = 0.003) and amniotic sac weight (P = 0.004); while the group affected the number of cotyledons (P = 0.0009), and the fetal heart weight (P = 0.018). All these parameters were larger in the ET_D9 group compared with ET_D7, and in males compared with females. There was a positive correlation between P4 concentrations two days before ET and fetal weight and CRL, for each sex or considering all fetuses (R ∼0.4, p < 0.05). In conclusion, bovine embryos transferred into a uterus primed with higher P4 concentrations underwent enhanced development reflected in higher weight and size at the beginning of the fetal period.
受孕后第一周循环孕酮（P4）浓度升高与孵化后胚胎伸长加速有关。然而，其对胎儿发育的影响（如果有）尚不清楚。本研究的目的是确定妊娠42天时早期循环P4与胎儿及胎盘形态测量特征之间的关系。在107头小母牛中采用了一种先前验证过的异步胚胎移植（ET）模型（已知该模型会改变子宫对P4的暴露情况），分为两个重复组（重复组1：n = 51，重复组2：n = 56）。小母牛被随机分配到以下两组之一：在周期第7天接受第7天胚胎的（同步组；ET_D7，n = 49）和在周期第9天移植第7天胚胎的（异步组；ET_D9，n = 58）。ET_D9组小母牛的同步方案提前两天开始，以便两组在同一天进行胚胎移植。从发情后第3天到胚胎移植当天测定P4浓度。妊娠42天时宰杀怀孕小母牛以进行胎儿和胎盘形态测量。通过方差分析确定组、重复组、胎儿性别以及这些变量之间相互作用对胎儿和胎盘特征的影响，同时采用Pearson相关性分析来评估胚胎移植前两天和当天的P4浓度与胎儿参数之间的线性关系。与ET_D7组小母牛相比，ET_D9组小母牛在胚胎移植前4天子宫暴露于更高浓度的P4（P < 0.0001）。组和胎儿性别变量均影响胎儿顶臀长（CRL）（组：P < 0.0001，性别：P = 0.001）和胎儿体重（组：P = 0.006，性别：P = 0.003）。胎儿性别影响羊膜囊面积（P = 0.003）和羊膜囊重量（P = 0.004）；而组影响子叶数量（P = 0.0009）和胎儿心脏重量（P = 0.018）。与ET_D7组相比，ET_D9组所有这些参数更大，且雄性胎儿的这些参数大于雌性胎儿。对于每种性别或考虑所有胎儿，胚胎移植前两天的P4浓度与胎儿体重和CRL之间存在正相关（R ∼0.4，p < 0.05）。总之，移植到预先暴露于较高P4浓度子宫内的牛胚胎发育增强，在胎儿期开始时表现为体重和尺寸更大。
