Abstract
Background
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 the mammalian reproductive physiology, in this study, we have explored whether the endogenously produced melatonin can help the porcine oocyte in vitro maturation.
Results
We have found for the first time, that mitochondria are the major sites for melatonin biosynthesis in porcine oocytes. This mitochondrially originated melatonin reduces ROS production increases the activity of mitochondrial respiratory electron transport chain, mitochondrial biogenesis, and 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 abnormal distribution of mitochondria and decreased the ATP level porcine oocytes and inhibits their in vitro maturation. These abnormalities can be rescued by melatonin supplementation. in addition, we found that siAANAT can switches the mitochondrial oxidative phosphorylation to glycolysis, a Warberg 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 melatonin’s effects.
Conclusions
Taken together, the mitochondria of porcine oocyte can synthesize melatonin and improve the quality of oocyte maturation. The mitochondria of porcine oocyte can synthesize melatonin and improve the quality of oocyte maturation.These results provide an insight from novel aspect to study the oocyte maturation in the in vitro condition.