猪卵母细胞的体外成熟效率相对较低,这限制了体外猪胚胎的产生。由于褪黑激素参与哺乳动物的生殖生理,在这项研究中,我们已经探讨了内源性褪黑素是否有助于猪卵母细胞的体外成熟。我们发现,在文献中第一次,线粒体是猪卵母细胞中褪黑激素生物合成的主要位点。这种线粒体起源的褪黑激素减少了ROS的产生并增加了线粒体呼吸电子传递链的活性,线粒体生物发生,线粒体膜电位,和ATP生产。因此,褪黑激素可改善卵母细胞的质量及其体外成熟。相比之下,siRNA敲低AANAT(siAANAT)引起的褪黑激素水平降低与线粒体的异常分布有关,降低猪卵母细胞的ATP水平并抑制其体外成熟。这些异常可以通过补充褪黑激素来挽救。此外,我们发现siAANAT将线粒体氧化磷酸化转换为糖酵解,Warburg效应。这种代谢改变也可以通过补充褪黑激素来纠正。褪黑激素的所有这些活性似乎都是由其膜受体介导的,因为非选择性褪黑激素受体拮抗剂Luzindole可以减弱褪黑激素的作用。一起来看,猪卵母细胞线粒体能合成褪黑素,提高卵母细胞成熟质量。这些结果提供了从新的方面研究卵母细胞在体外条件下成熟的见解。
The in vitro maturation efficiency of porcine oocytes is relatively low, and this limits the production of in vitro porcine embryos. Since melatonin is involved in mammalian reproductive physiology, in this study, we have explored whether endogenously produced melatonin can help in porcine oocyte in vitro maturation. We have found, for the first time in the literature, that mitochondria are the major sites for melatonin biosynthesis in porcine oocytes. This mitochondrially originated melatonin reduces ROS production and increases the activity of the mitochondrial respiratory electron transport chain, mitochondrial biogenesis, mitochondrial membrane potential, and ATP production. Therefore, melatonin improves the quality of oocytes and their in vitro maturation. In contrast, the reduced melatonin level caused by siRNA to knockdown AANAT (siAANAT) is associated with the abnormal distribution of mitochondria, decreasing the ATP level of porcine oocytes and inhibiting their in vitro maturation. These abnormalities can be rescued by melatonin supplementation. In addition, we found that siAANAT switches the mitochondrial oxidative phosphorylation to glycolysis, a Warburg effect. This metabolic alteration can also be corrected by melatonin supplementation. All these activities of melatonin appear to be mediated by its membrane receptors since the non-selective melatonin receptor antagonist Luzindole can blunt the effects of melatonin. Taken together, the mitochondria of porcine oocytes can synthesize melatonin and improve the quality of oocyte maturation. These results provide an insight from a novel aspect to study oocyte maturation under in vitro conditions.