Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Anhui Province Key Laboratory of Reproductive Health and Genetics, Biopreservation and Artificial Organs, Anhui Provincial Engineering Research Center, Anhui Medical University, Hefei, PR China.
Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Anhui Province Key Laboratory of Reproductive Health and Genetics, Biopreservation and Artificial Organs, Anhui Provincial Engineering Research Center, Anhui Medical University, Hefei, PR China.
Life Sci. 2019 Oct 15;235:116810. doi: 10.1016/j.lfs.2019.116810. Epub 2019 Aug 28.
Previous reports have demonstrated that melatonin exists in multiple extrapineal sites, and higher amounts of melatonin are present in human follicular fluid than in serum, which indicates that it might play key roles in human oocyte maturation and subsequent embryonic development. Melatonin has been shown to be a potent antioxidant and might be beneficial to human oocytes during in vitro maturation (IVM). However, the underlying mechanisms of melatonin action during IVM have not been thoroughly investigated.
Immunofluorescence staining, western blotting, and ELISA were applied to investigate whether melatoninergic components are expressed in the cultured human ovarian cumulus cells. TMRE staining and Fluo-4 AM staining were performed to detect the mitochondrial membrane potential and intracellular Ca levels of immature human oocytes respectively.
First, cultured human ovary cumulus cells synthesized melatonin in vitro, and it expressed serotonin (the precursor of melatonin) and the two key enzymes, i.e. N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT). Additionally, the results suggest that melatonin maintains the mitochondrial membrane potential and decrease excessive Ca levels in immature human oocytes during IVM.
In conclusion, we provide evidence that the melatoninergic components were expressed in cultured human ovarian cumulus cells, and melatonin might reduce oxidative stress of human oocytes by ameliorating mitochondrial function. In view of the significant clinical value that immature human oocytes have in assisted reproductive technology (ART), our findings highlight a potential treatment strategy of using melatonin to improve mitochondrial function and to enhance the quality of human oocytes during IVM.
先前的报告表明褪黑素存在于多个松果体外部位，并且在人类卵泡液中存在的褪黑素含量高于血清，这表明它可能在人类卵母细胞成熟和随后的胚胎发育中发挥关键作用。褪黑素已被证明是一种有效的抗氧化剂，并且在体外成熟（IVM）期间可能对人类卵母细胞有益。然而，褪黑素在 IVM 期间作用的潜在机制尚未得到彻底研究。
应用免疫荧光染色、western blot 和 ELISA 来研究褪黑素能成分是否在培养的人卵巢颗粒细胞中表达。TMRE 染色和 Fluo-4 AM 染色分别用于检测未成熟人卵母细胞的线粒体膜电位和细胞内 Ca 水平。
首先，培养的人卵巢颗粒细胞在体外合成褪黑素，并且表达血清素（褪黑素的前体）和两种关键酶，即 N-乙酰转移酶（NAT）和羟基吲哚-O-甲基转移酶（HIOMT）。此外，结果表明褪黑素在 IVM 期间维持未成熟人卵母细胞的线粒体膜电位并降低过度的 Ca 水平。
总之，我们提供了证据表明褪黑素能成分在培养的人卵巢颗粒细胞中表达，并且褪黑素可以通过改善线粒体功能来减少人类卵母细胞的氧化应激。鉴于未成熟人卵母细胞在辅助生殖技术（ART）中的重要临床价值，我们的发现强调了一种潜在的治疗策略，即使用褪黑素改善线粒体功能并提高 IVM 期间人类卵母细胞的质量。
