Marei Waleed F A, De Bie Jessie, Mohey-Elsaeed Omnia, Wydooghe Eline, Bols Peter E J, Leroy Jo L M R
Gamete Research Centre, Department of Veterinary Sciences, University of Antwerp, Wilrijk, Belgium.
Department of Theriogenology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt.
Biol Reprod. 2017 Jun 1;96(6):1181-1196. doi: 10.1093/biolre/iox046.
Elevated concentrations of free fatty acids (FFAs), predominantly palmitic, stearic, and oleic acids (PSO), exert detrimental effects on oocyte developmental competence. This study examined the effects of omega-3 alpha-linolenic acid (ALA) during in vitro oocyte maturation (IVM) in the presence of PSO on subsequent embryo development and quality, and the cellular mechanisms that might be involved. Bovine cumulus-oocyte complexes (COCs) were supplemented during IVM with ALA (50 μM), PSO (425 μM), or PSO+ALA. Compared with FFA-free controls (P < 0.05), PSO increased embryo fragmentation and decreased good quality embryos on day 2 postfertilization. Day 7 blastocyst rate was also reduced. Day 8 blastocysts had lower cell counts and higher apoptosis but normal metabolic profile. In the PSO group, cumulus cell (CC) expansion was inhibited with an increased CC apoptosis while COC metabolism was not affected. Mitochondrial inner membrane potential (MMP; JC-1 staining) was reduced in the CCs and oocytes. Heat shock protein 70 (HSP70) but not glucose-regulated protein 78 kDa (GRP78, known as BiP; an endoplasmic reticulum stress marker) was upregulated in the CCs. Higher reactive oxygen species levels (DCHFDA staining) were detected in the oocytes. In contrast, adding ALA in the presence of PSO normalized embryo fragmentation, cleavage, blastocyst rates, and blastocyst quality compared to controls (P > 0.05). Combined treatment with ALA also reduced CC apoptosis, partially recovered CC expansion, abrogated the reduction in MMP in the CCs but not in the oocytes, and reduced BiP and HSP70 expression in CCs, compared with PSO only (P < 0.05). In conclusion, ALA supplementation protected oocyte developmental capacity under lipotoxic conditions mainly by protecting cumulus cell viability.
游离脂肪酸（FFA）浓度升高，主要是棕榈酸、硬脂酸和油酸（PSO），会对卵母细胞的发育能力产生有害影响。本研究检测了在PSO存在的情况下，ω-3α-亚麻酸（ALA）在体外卵母细胞成熟（IVM）过程中对后续胚胎发育和质量的影响，以及可能涉及的细胞机制。在IVM期间，向牛卵丘-卵母细胞复合体（COC）中添加ALA（50μM）、PSO（425μM）或PSO + ALA。与无FFA的对照组相比（P < 0.05），PSO增加了受精后第2天的胚胎碎片率，并降低了优质胚胎的比例。第7天的囊胚率也降低了。第8天的囊胚细胞数量较少，凋亡率较高，但代谢谱正常。在PSO组中，卵丘细胞（CC）的扩展受到抑制，CC凋亡增加，而COC代谢未受影响。CC和卵母细胞中的线粒体内膜电位（MMP；JC-1染色）降低。CC中热休克蛋白70（HSP70）上调，但葡萄糖调节蛋白78 kDa（GRP78，也称为BiP；一种内质网应激标志物）未上调。在卵母细胞中检测到较高的活性氧水平（DCHFDA染色）。相比之下，与对照组相比（P > 0.05），在PSO存在的情况下添加ALA可使胚胎碎片率、卵裂率、囊胚率和囊胚质量正常化。与仅使用PSO相比（P < 0.05），ALA联合处理还降低了CC凋亡，部分恢复了CC扩展，消除了CC中MMP的降低，但未消除卵母细胞中的降低，并降低了CC中BiP和HSP70的表达。总之，补充ALA主要通过保护卵丘细胞活力来保护脂毒性条件下的卵母细胞发育能力。
