title: Recovery of mitochondrial function and endogenous antioxidant systems in vitrified bovine oocytes during extended in vitro culture.
abstract: This study was designed to examine the recovery of mitochondrial function and endogenous antioxidant systems in vitrified oocytes during extended incubations. After 16 hr of in vitro maturation, bovine meiosis-II oocytes were vitrified, and then surviving oocytes were cultured an additional 8 hr. ATP content, ATP synthase activity, expression of ATP synthase F0 subunit 6 (ATP6) and 8 (ATP8) genes, and reactive oxygen species (ROS) levels were investigated in the vitrified oocytes during this additional period (4 or 8 hr). The results showed that: (1) the ATP content and ATP synthase activities in vitrified oocytes at 8 hr post-warming (754.6 fmol, 25.9 nmol NADH/min/mg) were significantly higher than in oocytes immediately warmed (568.3 fmol, 8.7 nmol NADH/min/mg), but still lower than in control oocytes (901.5 fmol, 30.7 nmol NADH/min/mg); (2) the relative expression of ATP6 and ATP8 was initially down-regulated in oocytes when they were first warmed, increased by 4 hr post-warming, and were again down-regulated by 8 hr post-warming; (3) ROS levels in oocytes at 0, 4, and 8 hr post-warming were significantly higher than in control oocytes; and (4) after parthenogenetic activation, the blastocyst rate of oocytes at 8 hr post-warming (26.7%) was significantly higher than that of oocytes immediately warmed (16.9%). These results indicated that mitochondrial function and endogenous antioxidant systems recovered significantly better in vitrified-thawed bovine oocytes with 8 hr of additional incubation, but they did not achieve the activity levels found in fresh oocytes.
authors.affiliation: Embryo Biotechnology and Reproduction Laboratory, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, PR China.
authors.forename: Xue-Ming
authors.initials: XM
authors.lastname: Zhao
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Du
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.forename: Hai-Sheng
authors.initials: HS
authors.lastname: Hao
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Tong
authors.initials: T
authors.lastname: Qin
authors.forename: Hua-Bin
authors.initials: HB
authors.lastname: Zhu
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D000975:Antioxidants / Q000378:metabolism / Q000502:physiology*; D001755:Blastocyst / Q000378:metabolism / Q000502:physiology; D002417:Cattle; D018929:Cell Culture Techniques / Q000379:methods*; D005260:Female; D008928:Mitochondria / Q000502:physiology*; D025261:Mitochondrial Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D058989:Vitrification
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate; D025261:Mitochondrial Proton-Translocating ATPases