Mitochondria Synthesize Melatonin to Ameliorate Its Function and Improve Mice Oocyte’s Quality under in Vitro Conditions.

The physiology of oocyte in vitro maturation remains elusive. Generally, the oocytes have a very low maturation rate under in vitro conditions.

In the current study, we found that melatonin promotes the maturation of oocytes in which mitochondria play a pivotal role. It was identified that;

1. mitochondria are the major sites for melatonin synthesis in oocytes and they synthesize large amounts of melatonin during their maturation;
2. melatonin improves mitochondrial function by increased mtDNA copy, mitochondrial membrane potential (ΔΨm) and mitochondrial distribution and ATP production in oocytes;
3. the meiotic spindle assembly is enhanced;
4. melatonin reduces ROS production and inhibits 8-oxodG formation, thereby protecting potential DNA mutation from oxidative damage.

As a result, melatonin improves the quality of oocytes, significantly accelerates the developmental ability of IVF embryo. The results provide novel knowledge on the physiology of oocyte’s maturation, especially under in vitro conditions.