Department of Animal Sciences, Center for Nutrition and Pregnancy, North Dakota State University, Fargo, ND 58108, USA.
Animal. 2013 Sep;7(9):1500-7. doi: 10.1017/S1751731113001006. Epub 2013 Jun 13.
Dietary melatonin supplementation during mid- to late-gestation increased umbilical artery blood flow and caused disproportionate fetal growth. This melatonin-induced increase in umbilical artery blood flow may alter nutrient availability to the fetus, which may lead to alterations in fetal size. The objectives of the current experiment were to determine amino acid (AA) and glucose concentrations as well as AA and glucose flux across the uteroplacenta using a mid- to late-gestation model of intrauterine growth restriction supplemented with dietary melatonin as a 2 × 2 factorial design. At day 50 of gestation, 32 ewes were supplemented with 5 mg of melatonin (MEL) or no melatonin (CON) and were allocated to receive 100% (adequate; ADQ) or 60% (restricted; RES) of nutrient requirements. On day 130 of gestation, uterine and umbilical blood flows were determined via Doppler ultrasonography during a non-survival surgery. Blood samples were collected under general anesthesia from the maternal saphenous artery, gravid uterine vein, umbilical artery, and umbilical vein for AA analysis and glucose. Total α-AA concentrations in maternal artery and gravid uterine vein were decreased (P < 0.05) in RES v. ADQ fed ewes. Maternal arterial - venous difference in total α-AA was increased (P ⩽ 0.01) in RES v. ADQ fed ewes, while total uterine α-AA flux was not different (P > 0.40) across all treatment groups. Fetal venous - arterial difference in total α-AA as well as uteroplacental flux of total α-AA were decreased (P < 0.05) in CON-RES v. CON-ADQ, and similar (P > 0.20) in MEL-RES v. CON-ADQ. Maternal concentrations and uterine flux of branched-chain AA (BCAA) were not different across all treatment groups; however, fetal uptake of BCAA was decreased (P < 0.05) in CON-RES v. CON-ADQ, and similar (P > 0.20) in MEL-RES v. CON-ADQ. Uterine uptake of glucose was not different (P ⩾ 0.08) across all treatment groups, while uteroplacental uptake of glucose was increased (P ⩽ 0.05) in RES v. ADQ ewes. In conclusion, maternal nutrient restriction increased maternal arterial - venous difference in total α-AA, while total uterine α-AA flux was unaffected by maternal nutrient restriction. Melatonin supplementation did not impact maternal serum concentrations or uterine flux of glucose or AA; however, melatonin did improve fetal BCAA uptake during maternal nutrient restriction.
在妊娠中期至晚期补充膳食褪黑素会增加脐动脉血流量，并导致胎儿生长不成比例。这种褪黑素引起的脐动脉血流量增加可能会改变胎儿的营养供应，从而导致胎儿大小的改变。本实验的目的是确定氨基酸 (AA) 和葡萄糖浓度以及使用妊娠中期至晚期宫内生长受限的模型通过子宫胎盘的 AA 和葡萄糖通量，该模型补充膳食褪黑素作为 2×2 析因设计。在妊娠第 50 天，32 只母羊补充了 5mg 的褪黑素 (MEL) 或没有褪黑素 (CON)，并分配接受 100% (充足; ADQ) 或 60% (限制; RES) 的营养需求。在妊娠第 130 天，通过多普勒超声在非存活手术期间确定子宫和脐动脉血流量。在全身麻醉下从母体隐静脉、妊娠子宫静脉、脐动脉和脐静脉采集血液样本进行 AA 分析和葡萄糖。与 ADQ 喂养的母羊相比，RES 喂养的母羊的母体动脉和妊娠子宫静脉中的总 α-AA 浓度降低 (P<0.05)。与 ADQ 喂养的母羊相比，RES 喂养的母羊的母体动脉-静脉总 α-AA 差异增加 (P ⩽ 0.01)，而所有治疗组的总子宫 α-AA 通量没有差异 (P>0.40)。CON-RES 组的胎儿静脉-动脉总 α-AA 差异以及子宫胎盘总 α-AA 通量均低于 CON-ADQ 组 (P<0.05)，而 MEL-RES 组与 CON-ADQ 组相似 (P>0.20)。CON-RES 组的母羊浓度和子宫胎盘支链氨基酸 (BCAA) 通量均低于 CON-ADQ 组，而 MEL-RES 组与 CON-ADQ 组相似 (P>0.20)。然而，CON-RES 组的胎儿摄取 BCAA 减少 (P<0.05)，而 MEL-RES 组与 CON-ADQ 组相似 (P>0.20)。所有治疗组的子宫葡萄糖摄取没有差异 (P ⩾ 0.08)，而 RES 组的子宫胎盘葡萄糖摄取增加 (P ⩽ 0.05)。总之，母体营养限制增加了母体动脉-静脉总 α-AA 差异，而母体营养限制对总子宫 α-AA 通量没有影响。褪黑素补充剂对母体血清浓度或葡萄糖或 AA 的子宫通量没有影响;然而，褪黑素确实改善了胎儿在母体营养限制期间的 BCAA 摄取。
