Aging-related Changes in In Vitro-matured Bovine Oocytes: Oxidative Stress, Mitochondrial Activity and ATP Content After Nuclear Maturation

• Published in: Journal of Reproduction and Development Vol. 60; no. 2; pp. 136 - 142
• Main Authors: HUANG, Weiping, NAGANO, Masashi, YANAGAWA, Yojiro, TAKAHASHI, Yoshiyuki, KOYAMA, Keisuke, KANG, Sung-Sik
• Format: Journal Article
• Language: English
• Published: Japan THE SOCIETY FOR REPRODUCTION AND DEVELOPMENT 2014; The Society for Reproduction and Development
• Subjects: Adenosine Triphosphate - metabolism; Age Factors; Aging; Animals; ATP; Bovine oocytes; Cattle - physiology; Cell Nucleus - metabolism; Embryonic Development; Female; Fertilization in Vitro - methods; Fertilization in Vitro - veterinary; In Vitro Oocyte Maturation Techniques - veterinary; Male; Microscopy, Fluorescence - veterinary; Mitochondria; Mitochondria - metabolism; Mitochondria - physiology; Oocytes - cytology; Oocytes - growth & development; Oocytes - metabolism; Oocytes - physiology; Original; Oxidative Stress - physiology; Reactive Oxygen Species - metabolism; ROS
• ISSN: 0916-8818; 1348-4400
• DOI: 10.1262/jrd.2013-115

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.