Zhu Tianqi, Guan Shengyu, Lv Dongying, Zhao Mengmeng, Yan Laiqing, Shi Li, Ji Pengyun, Zhang Lu, Liu Guoshi
Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, Key Laboratory of Animal Genetics Improvement, Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing, China.
Front Cell Dev Biol. 2021 Apr 1;9:648209. doi: 10.3389/fcell.2021.648209. eCollection 2021.
Lipid is a crucial energy resource for mammalian oocyte. Melatonin could benefit the maturation of porcine oocyte , but the related mechanism is not elucidated yet. In the current study, methods to monitor lipid metabolism in single live oocytes were firstly established using probes (Lipi-Blue and Lipi-Green). It was observed that both lipid biogenesis and lipolysis occurred in maturing oocyte, but the general level of lipids dropped. Then maturing oocytes stained with probes were treated with melatonin or lipid metabolic-related inhibitors (triacsin C, rotenone, or etomoxir). The results showed that the lipid metabolism and maturation of porcine oocytes were all disrupted and that melatonin rescued the oocytes treated with triacsin C or rotenone, but not those treated with etomoxir. Further investigation demonstrated that cumulus cells are able to transfer lipids to oocytes via gap junctions. It was also observed that melatonin receptors exist in cumulus cells and are required for oocytes to maintain lipid metabolism. Meanwhile, the global gene expressing in cumulus cells was also modulated by melatonin, especially the genes related to antioxidants (, , , , , and ), lipid metabolism (, , , , etc.), and mitochondrial respiration (, , , and the genes of ATP synthase). Altogether the current research demonstrates that melatonin modulates lipid metabolism in maturing oocytes through its receptors in cumulus cells and benefits the developmental competence of oocytes.
脂质是哺乳动物卵母细胞至关重要的能量来源。褪黑素有助于猪卵母细胞的成熟，但其相关机制尚未阐明。在本研究中，首先使用探针（Lipi - Blue和Lipi - Green）建立了监测单个活卵母细胞脂质代谢的方法。观察到在成熟卵母细胞中脂质生物合成和脂解均发生，但脂质的总体水平下降。然后用褪黑素或脂质代谢相关抑制剂（三辛脂酰辅酶A、鱼藤酮或依托莫昔）处理用探针染色的成熟卵母细胞。结果表明，猪卵母细胞的脂质代谢和成熟均受到破坏，褪黑素挽救了用三辛脂酰辅酶A或鱼藤酮处理的卵母细胞，但不能挽救用依托莫昔处理的卵母细胞。进一步研究表明，卵丘细胞能够通过缝隙连接将脂质转移到卵母细胞。还观察到卵丘细胞中存在褪黑素受体，卵母细胞维持脂质代谢需要这些受体。同时，卵丘细胞中的全局基因表达也受到褪黑素的调节，特别是与抗氧化剂（、、、、、和）、脂质代谢（、、、、等）以及线粒体呼吸（、、、和ATP合酶基因）相关的基因。总之，当前研究表明，褪黑素通过其在卵丘细胞中的受体调节成熟卵母细胞中的脂质代谢，并有利于卵母细胞的发育能力。
