AUTHOR=Qin Jianpeng , Guo Shichao , Yang Jinyu , Qazi Izhar Hyder , Pan Bo , Lv Tianyi , Zang Shengqin , Fang Yi , Zhou Guangbin 

TITLE=Melatonin Promotes in vitro Development of Vitrified-Warmed Mouse GV Oocytes, Potentially by Modulating Phosphorylation of Drp1

JOURNAL=Frontiers in Veterinary Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2021.752001

DOI=10.3389/fvets.2021.752001

ISSN=2297-1769

ABSTRACT=<p>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 <italic>in vitro</italic> 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 (<italic>P</italic> &lt; <italic>0.05</italic>). Furthermore, the rates of <italic>in vitro</italic> maturation, cleavage and blastocyst formation after parthenogenetic activation were decreased (<italic>P</italic> &lt; <italic>0.05</italic>). (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 (<italic>Sirt1, Pgc-1</italic>α<italic>, Tfam</italic>) were all decreased (<italic>P</italic> &lt; <italic>0.05</italic>), and (3) Reactive oxygen species (ROS) level, early apoptosis level, Cytochrome C release and mRNA levels of pro-apoptotic related genes (<italic>Bax, Caspase9, Caspase3</italic>) in MII oocytes were all increased (<italic>P</italic> &lt; <italic>0.05</italic>). The results of this study further revealed that negative impacts of GV oocyte cryopreservation were mitigated by supplementation of warming and <italic>in vitro</italic> maturation media with 10<sup>−7</sup>mol /L melatonin or 2 x 10<sup>−5</sup>mol/L Mdivi-1 (Drp1 inhibitor). Therefore, we concluded that 10<sup>−7</sup>mol/L melatonin improved mitochondrial function, reduced oxidative stress and inhibited apoptosis by regulating phosphorylation of Drp1, thereby enhancing <italic>in vitro</italic> development of vitrified-warmed mouse GV oocytes.</p>