Department of Theriogenology and Biotechnology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
Int J Mol Sci. 2018 May 26;19(6):1581. doi: 10.3390/ijms19061581.
Melatonin is a multifunctional molecule with numerous biological activities. The fact that melatonin modulates the functions of porcine granulosa cells via the MT2 receptor suggests the possibility of MT2 receptor-mediation for melatonin to promote cumulus expansion of porcine cumulus-oocyte complexes (COCs). Therefore, we investigated the presence of MT2 in porcine COCs, and the effects of melatonin with or without selective MT2 antagonists (luzindole and 4-P-PDOT) on this process; COCs underwent in vitro maturation culturing with six different conditions (control, melatonin, luzindole, 4-P-PDOT, melatonin + luzindole or melatonin + 4-P-PDOT). Cumulus expansion, oocyte nuclear maturation, and subsequent embryo development after parthenogenetic activation (PA) were evaluated. In experiment 1, MT2 was expressed in both oocytes and cumulus cells. In experiment 2, melatonin significantly increased the proportion of complete cumulus expansion (degree 4), which was inhibited by simultaneous addition of either luzindole or 4-P-PDOT. A similar pattern was observed in the expression of genes related to cumulus expansion, apoptosis, and . In experiment 3, no significant difference was observed in immature, degenerate, and MII oocyte rates among the groups. In experiment 4, melatonin significantly increased blastocyst formation rates and total blastocyst cell numbers after PA, but these effects were abolished when either luzindole or 4-P-PDOT was added concomitantly. In conclusion, our results indicate that the MT2 receptor mediated the stimulatory effects of melatonin on porcine cumulus expansion and subsequent embryo development.
褪黑素是一种具有多种生物活性的多功能分子。褪黑素通过 MT2 受体调节猪颗粒细胞的功能这一事实表明，MT2 受体介导的褪黑素可能促进猪卵丘-卵母细胞复合体（COC）的卵丘扩展。因此，我们研究了 MT2 在猪 COC 中的存在，以及褪黑素及其选择性 MT2 拮抗剂（luzindole 和 4-P-PDOT）对这一过程的影响；COC 在体外成熟培养中经历了六种不同的条件（对照、褪黑素、luzindole、4-P-PDOT、褪黑素+ luzindole 或褪黑素+ 4-P-PDOT）。评估卵丘扩展、卵母细胞核成熟以及随后的孤雌激活（PA）胚胎发育。在实验 1 中，MT2 在卵母细胞和卵丘细胞中均有表达。在实验 2 中，褪黑素显著增加了完全卵丘扩展的比例（第 4 级），同时添加 luzindole 或 4-P-PDOT 会抑制这种扩展。在与卵丘扩展、凋亡和相关的基因表达中观察到类似的模式。在实验 3 中，各组之间未观察到未成熟、退化和 MII 卵母细胞率的显著差异。在实验 4 中，褪黑素显著增加了 PA 后的囊胚形成率和总囊胚细胞数，但当同时添加 luzindole 或 4-P-PDOT 时，这些效应被消除。总之，我们的结果表明，MT2 受体介导了褪黑素对猪卵丘扩展和随后胚胎发育的刺激作用。
