Aging-related changes in in vitro-matured bovine oocytes: oxidative stress, mitochondrial activity and ATP content after nuclear maturation.
The objective of this research was to clarify the aging-related changes in in vitro-matured bovine oocytes. Firstly, we examined the fertilization and embryonic development of bovine oocytes after 22 and 30-34 h of in vitro maturation (IVM). The oocytes after 30-34 h of IVM (penetrated by sperm at around 40 h after starting IVM) showed a lower developmental rate to blastocysts (P<0.01), although normal fertilization rates were similar regardless of IVM duration. In the next experiment, reactive oxygen species (ROS), mitochondrial activity and ATP content in oocytes after 20, 30 and 40 h of IVM were examined. The lowest level of ROS was found in the group subjected to 30 h of IVM. The mitochondrial activity and ATP content in the group subjected to 40 h of IVM were higher than in the group subjected to 20 h of IVM (P<0.01), and those in the group subjected to 30 h of IVM showed intermediate values. Thereafter, the mitochondrial activities at 3 days after in vitro fertilization in embryos derived from the oocytes subjected to 22 and 34 h of IVM were evaluated. In the group subjected to 34 h of IVM, high-polarized mitochondria were frequently observed at the periphery of blastomeres. The present results suggest that high mitochondrial activity observed in oocytes after prolonged IVM culture and localization of high-polarized mitochondria at the periphery of blastomeres during early embryonic development may be associated with the low developmental competence in aged bovine oocytes.
Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
Keisuke
K
Koyama
Sung-Sik
SS
Kang
Weiping
W
Huang
Yojiro
Y
Yanagawa
Yoshiyuki
Y
Takahashi
Masashi
M
Nagano
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000367:Age Factors; D000818:Animals; D002417:Cattle / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods / Q000662:veterinary*; D059471:In Vitro Oocyte Maturation Techniques / Q000662:veterinary; D008297:Male; D008856:Microscopy, Fluorescence / Q000662:veterinary; D008928:Mitochondria / Q000378:metabolism / Q000502:physiology*; D009865:Oocytes / Q000166:cytology / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D018384:Oxidative Stress / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism
D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate