USDA-ARS, Forage-Animal Production Research Unit, Lexington, KY.
Department of Animal and Veterinary Science, Clemson University, Clemson, SC.
J Anim Sci. 2019 Apr 3;97(4):1891-1902. doi: 10.1093/jas/skz069.
Previous research has shown that livestock exposed to ergot alkaloids results in decreased vasoactivity of gastrointestinal and peripheral vasculature. Little is known regarding the effect ergot alkaloid exposure during gestation may have on vasculature supporting the fetus. The objective of this study was to evaluate contractile responses of uterine and umbilical arteries collected from ewes consuming ergot alkaloids during gestation. On day 35 of gestation, 36 Suffolk ewes (78.24 ± 9.5 kg) were assigned to endophyte-infected (E+) or endophyte-free (E-) tall fescue seed treatments that were fed either throughout or switched on day 86 of gestation, creating four seed treatments E+E+, E+E-, E-E+, and E-E-. Ewes were fed E+ tall fescue seed to provide 1.77 mg of total ergovaline ⋅ hd-1 ⋅ d-1 with E- ewes receiving the same quantity of E- seed. Gestation was terminated on day 133, and sections of uterine artery and umbilical cord were surgically collected. Only collections from 28 ewes (n = 7/treatment) were of sufficient viability to proceed with the contractility experiments. Arteries were cleaned, sliced into 2-mm cross sections, and suspended in multi-myograph chambers containing 5 mL of continuously oxygenated Krebs-Henseleit buffer. Vessels were exposed to increasing concentrations (5 × 10-8 to 1 × 10-4 M) of norepinephrine, serotonin, ergotamine, and ergovaline (5 × 10-9 to 1 × 10-5M; extract of tall fescue seed) in 15-min intervals. Increasing concentrations of norepinephrine generated a contractile response by the uterine artery (P < 0.05), but no response in the umbilical artery. Increasing concentrations of serotonin resulted in negligible responses in uterine preparations, whereas umbilical artery preparations were responsive (P < 0.05) to serotonin. Ewes receiving E+E+ and E-E+ treatments had decreased vasoactivity in umbilical arteries to serotonin with a dextral shift in concentrations where the response curve initiated (P < 0.05). Interestingly, uterine arteries were not responsive to exposure to ergotamine or ergovaline, whereas umbilical arteries were responsive (P < 0.05). Umbilical arteries collected from ewes receiving E-E- and E+E- were more vasoactive to ergot alkaloids (P < 0.05) than other treatments. These findings indicate that maternal blood supply to the placenta appears protected from negative effects of ergot alkaloids; however, umbilical vasculature is not, and this could adversely influence fetal growth.
先前的研究表明，接触麦角生物碱会导致胃肠道和外周血管的血管活性降低。关于在妊娠期间接触麦角生物碱可能对支持胎儿的血管产生的影响，知之甚少。本研究的目的是评估在妊娠期间摄入麦角生物碱的绵羊子宫和脐带动脉的收缩反应。在妊娠第 35 天，将 36 只萨福克母羊（78.24 ± 9.5 kg）分配到感染内生真菌（E+）或无内生真菌（E-）的高羊茅种子处理组中，这些种子在妊娠第 86 天之前或之后被喂食，形成四种种子处理组 E+E+、E+E-、E-E+和 E-E-。给 E+的母羊喂食高羊茅种子，以提供 1.77 mg 总麦角新碱 ⋅ hd-1 ⋅ d-1，而 E-的母羊则接受相同数量的 E-种子。妊娠于第 133 天终止，手术采集子宫动脉和脐带的部分。只有 28 只母羊（n = 7/处理）的收集物具有足够的活力，可以进行收缩性实验。动脉被清洗，切成 2-mm 横截面，然后悬挂在含有 5 mL 连续充氧 Krebs-Henseleit 缓冲液的多肌描记器室中。血管暴露于浓度递增的去甲肾上腺素（5 × 10-8 至 1 × 10-4 M）、血清素、麦角胺和麦角新碱（5 × 10-9 至 1 × 10-5 M；高羊茅种子提取物）中，每隔 15 分钟增加一次。子宫动脉对去甲肾上腺素浓度的增加产生收缩反应（P < 0.05），但脐带动脉没有反应。血清素浓度的增加导致子宫制剂的反应可忽略不计，而脐带动脉制剂对血清素的反应敏感（P < 0.05）。接受 E+E+和 E-E+处理的母羊对血清素的脐动脉血管活性降低，反应曲线起始的浓度出现右旋移位（P < 0.05）。有趣的是，子宫动脉对麦角胺或麦角新碱没有反应，而脐带动脉有反应（P < 0.05）。接受 E-E-和 E+E-处理的母羊的脐带动脉对麦角生物碱的血管活性更高（P < 0.05）比其他处理。这些发现表明，母体血液向胎盘的供应似乎免受麦角生物碱的负面影响；然而，脐带血管不受影响，这可能会对胎儿生长产生不利影响。
