Previous studies have shown that melatonin can mitigate cryopreservation-induced mitochondrial dysfunction in oocytes; however, the underlying molecular mechanism remains unclear. The objective of the present study was to investigate whether melatonin can improve the mitochondrial function during in vitro maturation of vitrified-warmed mouse germinal vesicle (GV) oocytes by modulating phosphorylation of dynamin related protein 1 (Drp1). Vitrification/warming procedures resulted in the following: (1) After cryopreservation of mouse GV oocytes, the phosphorylation level of Drp1 at Ser616 (p-Drp1 Ser616) in metaphase II (MII) oocytes was increased (P < 0.05). Furthermore, the rates of in vitro maturation, cleavage and blastocyst formation after parthenogenetic activation were decreased (P < 0.05). (2) In MII oocytes, the expression levels of translocase of the mitochondrial outer membrane 20 (TOMM20), mitochondrial membrane potential (MMP), adenosine triphosphate (ATP) content, and mRNA levels of mitochondrial biogenesis-related genes (Sirt1, Pgc-1α, Tfam) were all decreased (P < 0.05), and (3) Reactive oxygen species (ROS) level, early apoptosis level, Cytochrome C release and mRNA levels of pro-apoptotic related genes (Bax, Caspase9, Caspase3) in MII oocytes were all increased (P < 0.05). The results of this study further revealed that negative impacts of GV oocyte cryopreservation were mitigated by supplementation of warming and in vitro maturation media with 10⁻⁷mol /L melatonin or 2 x 10⁻⁵mol/L Mdivi-1 (Drp1 inhibitor). Therefore, we concluded that 10⁻⁷mol/L melatonin improved mitochondrial function, reduced oxidative stress and inhibited apoptosis by regulating phosphorylation of Drp1, thereby enhancing in vitro development of vitrified-warmed mouse GV oocytes.

以前的研究表明，褪黑激素可以减轻冷冻保存引起的卵母细胞线粒体功能障碍；然而，潜在的分子机制仍不清楚。本研究的目的是研究褪黑激素是否可以改善线粒体功能体外通过调节动力蛋白 1 (Drp1) 的磷酸化使玻璃化加热的小鼠生发囊 (GV) 卵母细胞成熟。玻璃化/加温程序导致以下结果：（1）小鼠 GV 卵母细胞冷冻保存后，中期 II（MII）卵母细胞中 Ser616（p-Drp1 Ser616）的 Drp1 磷酸化水平增加（磷 < 0.05）。此外，体外 孤雌生殖激活后的成熟、卵裂和囊胚形成减少。磷 < 0.05）。(2) MII卵母细胞线粒体外膜20(TOMM20)转位酶(TOMM20)、线粒体膜电位(MMP)、三磷酸腺苷(ATP)含量和线粒体生物合成相关基因mRNA水平的表达水平。Sirt1, Pgc-1α, Tfam) 都减少了 (磷 < 0.05)，和 (3) 活性氧 (ROS) 水平、早期凋亡水平、细胞色素 C 释放和促凋亡相关基因的 mRNA 水平（Bax、Caspase9、Caspase3) 在 MII 中的卵母细胞都增加了 (磷 < 0.05）。本研究的结果进一步揭示了 GV 卵母细胞冷冻保存的负面影响可以通过补充升温和体外含有 10 ^-7 mol/L 褪黑激素或 2 x 10 ^-5 mol/L Mdivi-1（Drp1 抑制剂）的成熟培养基。因此，我们得出结论，10 ^-7 mol/L 褪黑激素通过调节 Drp1 的磷酸化来改善线粒体功能，减少氧化应激并抑制细胞凋亡，从而增强体外 玻璃化加热小鼠 GV 卵母细胞的发育。