Diacylglycerol acyltransferase-1 (DGAT1) is one of the DGAT enzymes that catalyzes the final step in the synthesis of triacylglycerol, which is a major component of the lipid droplets in embryos. Intracellular lipids accumulated in embryos produced in vitro have been associated with reduced cryotolerance and quality. The objective of the present study was to investigate the influence of DGAT1 inhibition on embryo development, quality, and post-vitrification survival, in addition to expression profiles of selected lipid metabolism-regulating and oxidative stress genes. Bovine cumulus-oocyte complexes were matured and fertilized in vitro and were cultured in synthetic oviduct fluid (SOF) supplemented with 5% fetal calf serum (FCS) alone (Control) or with 1, 5, 10 or 50 μM DGAT1 inhibitor (A922500®; D1, D5, D10, and D50, respectively) or 0.1% dimethyl sulfoxide (CDMSO: vehicle for DGAT1 inhibitor dilution) from 54 h post-insemination until Day 8 post insemination. No differences were found in blastocyst yield on days 7 and 8 in Control, CDMSO, D10, and D50 groups. Embryos cultured with 10 or 50 μM DGAT1 inhibitor had greater mitochondrial activity (P < 0.01), and increased number of cells (P < 0.05), while the cytoplasmic lipid content was reduced (P < 0.01), the latter associated with altered expression profiles of selected genes regulating lipid metabolism or genes related with oxidative stress (transcript abundance increased for SLC2A1 and SLC2A5 and decreased for DGAT1 and GPX1). Importantly, the survival rate of blastocysts produced with 10 μM DGAT1 was higher than that of Control, CDMSO and D50 groups at 72 h after vitrification and warming (73.8 vs 57.1, 55.9 and 56.1%, respectively, P < 0.001). In conclusion, inhibition of DGAT1 synthesis in bovine embryos produced in vitro abrogates the negative effect of FCS by decreasing their lipid content, increasing mitochondria activity and improving embryo cryotolerance, as well as favoring the expression of lipid metabolism regulating and oxidative stress-related transcripts.

中文翻译：

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抑制二酰基甘油酰基转移酶-1 减少体外产生的牛囊胚中的脂质生物合成

Diacylglycerol acyltransferase-1 (DGAT1) 是 DGAT 酶之一，可催化三酰基甘油合成的最后一步，三酰基甘油是胚胎中脂滴的主要成分。体外产生的胚胎中积累的细胞内脂质与降低的耐低温性和质量有关。本研究的目的是研究 DGAT1 抑制对胚胎发育、质量和玻璃化后存活的影响，以及选定的脂质代谢调节基因和氧化应激基因的表达谱。牛卵丘-卵母细胞复合物在体外成熟和受精，并在合成输卵管液 (SOF) 中培养，该液体补充有 5% 胎牛血清 (FCS) 单独（对照）或 1、5、10 或 50 μM DGAT1 抑制剂 (A922500® ; 分别为 D1、D5、D10 和 D50) 或 0。1% 二甲基亚砜（CDMSO：用于 DGAT1 抑制剂稀释的载体）从授精后 54 小时到授精后第 8 天。在 Control、CDMSO、D10 和 D50 组中，第 7 天和第 8 天的囊胚产量没有发现差异。用 10 或 50 μM DGAT1 抑制剂培养的胚胎具有更高的线粒体活性（P < 0.01），细胞数量增加（P < 0.05），而细胞质脂质含量减少（P < 0.01），后者与表达谱改变有关调节脂质代谢的选定基因或与氧化应激相关的基因（SLC2A1 和 SLC2A5 的转录本丰度增加，而 DGAT1 和 GPX1 的转录本丰度减少）。重要的是，在玻璃化和加热后 72 小时，用 10 μM DGAT1 产生的囊胚的存活率高于 Control、CDMSO 和 D50 组（73.8 vs 57.1、55.9 和 56。1%，分别为 P < 0.001）。总之，在体外产生的牛胚胎中抑制 DGAT1 合成通过降低其脂质含量、增加线粒体活性和改善胚胎耐低温性以及有利于脂质代谢调节和氧化应激相关转录物的表达来消除 FCS 的负面影响。