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


He C, Wang J, Zhang Z, Yang M, Li Y5, Tian X, Ma T, Tao J, Zhu K, Song Y, Ji P, Liu G




Int J Mol Sci. 2016 Jun 14;17(6).

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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.

Complex functions of melatonin from the mitochondria in order to improve the quality of the oocyte. (Source: modified according to He C et al., 2016)




Oocytes themselves synthesize melatonin: melatonin levels in the ovarian homogenate and serum 4 and 8 hours following hCG stimulation (A) as well as in the media of the oocyte culture after 4 and 8 hours of culture. Melatonin improves the quality of the ovum: blastocyst cell number (C) as well as GSH (antioxidant) and ROS (free radicals) concentration (D) as a function of melatonin concentration. *p < 0,05; **p < 0,001 (Source: modified according to He C et al., 2016)








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