title: Melatonin effect during different maturation stages of oocyte and subsequent embryo development in mice.
abstract: BACKGROUND
  It is important to protect oocytes and embryos from oxidative stress in the culture medium. Melatonin has been shown to be a direct free radical scavenger.
  
  
  OBJECTIVE
  Effect of melatonin during in vitro oocyte maturation, fertilization and embryo development of mouse oocytes was evaluated.
  
  
  METHODS
  Oocytes from supper-ovulated mouse were divided to two groups: cumulus oocyte complexes (COCs, group I) and denuded COC (d-COCs, group II). The oocytes were cultured in maturation medium with different doses of melatonin (1×10(1)-10(5) nM). The cumulus expansion and nuclear status were evaluated after 24 h of in-vitro maturation. The oocytes were used for in-vitro fertilization. The fertilized oocytes were cultured in medium supplemented with different doses of melatonin.
  
  
  RESULTS
  The expansion (86.79%) and maturation (80.55%) rate of COCs increased in supplemented medium with 10 nM of melatonin vs. control group (73.33%), p=0.006 and p=0.026 respectively), but oocytes without cumulus cells indicated higher maturation rate at higher melatonin doses (10 and 100 M, 84.34% and 79.5% respectively( vs. 69.33% in control group (p=0.002). Fertilization rate was higher in treated medium with 1 μM of melatonin (93.75%, p=0.007). The rate of cleavage and blastocyst formation was promoted in medium supplemented with 10 and 100 nM of melatonin (92.37% and 89.36% vs. 81.25% in control group, p=0.002). We observed a dose dependent response to melatonin treatment in this experiment.
  
  
  CONCLUSIONS
  Exogenous melatonin can promote cumulus cell expansion, in vitro oocyte maturation, and embryo development. However we investigated a dose-dependent response in different stages of maturation and development. It may reflect sensitive rate of oocytes and embryos to culture conditions.
authors.affiliation: Cellular and Molecular Research Center, Faculty of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Mohammad Hadi
authors.initials: MH
authors.lastname: Bahadori
authors.affiliation: Department of Biology, Biology Faculty, Kharazmi (Tarbiat Moallem) University, Tehran, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Ghasemian
authors.affiliation: Department of Biology, Faculty of Sciences, Ashtian Branch, Islamic Azad University, Ashtian, Iran.
authors.forename: Mina
authors.initials: M
authors.lastname: Ramezani
authors.affiliation: Department of Anatomy, Faculty of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Zakieh
authors.initials: Z
authors.lastname: Asgari
keywords: Cumulus-oocyte complex; Development; In vitro oocyte maturation; Invitro fertilization; Melatonin