Department of Animal Sciences, University of Florida, Gainesville 32611.
Department of Animal Sciences, University of Florida, Gainesville 32611.
J Dairy Sci. 2019 Nov;102(11):10506-10513. doi: 10.3168/jds.2019-16839. Epub 2019 Sep 11.
Aflatoxin is a potent carcinogen often found in animal feedstuffs. Although it reportedly impairs development of the preimplantation pig embryo, it is not known whether it adversely affects development of the preimplantation bovine embryo. We conducted 3 experiments to investigate this possibility and determine whether deleterious effects of aflatoxin were caused by increased production of reactive oxygen species (ROS). Experiments were conducted with embryos produced in vitro and cultured after fertilization with various concentrations of aflatoxin. For experiment 1, embryos were treated with 0 (control), 40, 400, or 4,000 µg/L of aflatoxin B (AFB). Treatment at all concentrations of AFB tended to reduce cleavage rate, with the 2 highest concentrations having significant effects. As compared with the control, 40 µg/L AFB reduced the percentage of oocytes becoming blastocysts and the percentage of cleaved embryos becoming blastocysts (19.7 vs. 8.1% and 30.3 vs. 14.3%, respectively). Complete inhibition of blastocyst formation occurred at concentrations of 400 and 4,000 µg/L of AFB. Experiments 2 and 3 involved a 2 × 2 factorial design with effects of AFB (0 and 40 µg/L), the antioxidant Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid, a water-soluble analog of vitamin E; 0 and 5 µM), and their interaction on production of ROS in putative zygotes (experiment 2) and development to the blastocyst stage (experiment 3). Production of ROS was increased by AFB, and this effect was reversed by Trolox. However, Trolox did not prevent the reduction in development to the blastocyst stage caused by AFB. Thus, the anti-developmental effects of AFB are not caused solely by increased ROS production. Rather, other underlying mechanisms exist for the adverse effects of aflatoxin on embryonic development. Overall, results indicate the potential for feeding aflatoxin-contaminated feed to cause embryonic loss in cattle.
黄曲霉毒素是一种常见于动物饲料中的强致癌物质。尽管有报道称其会损害猪胚胎的着床前发育，但目前尚不清楚它是否会对牛胚胎的着床前发育产生不利影响。我们进行了 3 项实验来研究这种可能性，并确定黄曲霉毒素的有害影响是否是由活性氧（ROS）的产生增加引起的。实验是在体外受精后用不同浓度的黄曲霉毒素培养胚胎进行的。在实验 1 中，胚胎分别用 0（对照）、40、400 或 4000μg/L 的黄曲霉毒素 B（AFB）处理。所有浓度的 AFB 处理均趋向于降低卵裂率，其中最高的 2 个浓度具有显著影响。与对照组相比，40μg/L AFB 降低了卵母细胞发育成囊胚的百分比和卵裂胚胎发育成囊胚的百分比（分别为 19.7%对 8.1%和 30.3%对 14.3%）。400 和 4000μg/L 的 AFB 完全抑制了囊胚的形成。实验 2 和 3 采用 2×2 析因设计，研究了 AFB（0 和 40μg/L）、抗氧化剂 Trolox（6-羟基-2,5,7,8-四甲基色满-2-羧酸，维生素 E 的水溶性类似物；0 和 5μM）及其相互作用对假定受精卵（实验 2）和发育到囊胚阶段（实验 3）产生 ROS 的影响。AFB 增加了 ROS 的产生，而 Trolox 则逆转了这一效应。然而，Trolox 并不能阻止 AFB 引起的囊胚发育减少。因此，AFB 的抗发育作用不仅仅是由于 ROS 产生增加引起的。相反，黄曲霉毒素对胚胎发育的不良影响存在其他潜在机制。总的来说，结果表明，给牛喂食黄曲霉毒素污染的饲料可能会导致胚胎丢失。
