title: Combined inhibitory effects of pyruvate and low temperature on postovulatory aging of mouse oocytes.
abstract: This study tested the hypothesis that oocyte aging could be prevented for a longer time by reducing the culture temperature while supplementing the culture medium with more pyruvate. Newly ovulated mouse oocytes were cultured at various temperatures for various times in HCZB medium (Kimura and Yanagimachi, Biol Reprod 1995; 52:709-720) containing various concentrations of pyruvate before examining for aging parameters and developmental potential. The increase in susceptibility to activating stimuli was efficiently prevented when oocytes were cultured in HCZB with 10.27 mM pyruvate at 37°C for 6 h, 25°C for 24 h, 15°C for 96 h, and 5°C for 48 h. Satisfactory blastocyst development of both parthenotes and fertilized zygotes was achieved after oocyte culture in HCZB containing 10.27 mM pyruvate at 37°C for 6 h, 25°C for 24 h, 15°C for 36 h, and 5°C for 24 h. Transfer of two-cell embryos or blastocysts showed no difference between newly ovulated control oocytes and oocytes cultured at 15°C for 36 h in either term pregnancy, live young per pregnant recipient, live young/transferred embryos, or birth weight of young. Oocytes with impaired developmental potential after culture at 15°C for 96 h and at 5°C for 48 h showed unrecoverable decreases in the content of glutathione, the glutathione/oxidized glutathione ratio, the BCL2 content, and in the numbers of oocytes with normal spindles and cortical granule distribution, suggesting induction of oxidative stress, which caused oocyte apoptosis and cytoskeleton alterations by downregulating BCL2. Because oocytes cultured at 15°C for 36 h were activated or fertilized after a 6-h recovery culture, aging of ovulated mouse oocytes has been successfully prevented for 42 h without impairing their developmental potential.
authors.affiliation: College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai-an City, People's Republic of China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Ping
authors.initials: P
authors.lastname: Zhou
authors.forename: Tian-Yang
authors.initials: TY
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Cui
authors.forename: Ming-Jiu
authors.initials: MJ
authors.lastname: Luo
authors.forename: Jing-He
authors.initials: JH
authors.lastname: Tan
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology; D018929:Cell Culture Techniques / Q000379:methods; D016922:Cellular Senescence / Q000187:drug effects*; D003080:Cold Temperature; D003470:Culture Media; D046149:Embryo Culture Techniques / Q000379:methods / Q000662:veterinary; D004624:Embryo Transfer / Q000662:veterinary; D047108:Embryonic Development / Q000502:physiology; D000431:Ethanol / Q000494:pharmacology; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D005978:Glutathione / Q000032:analysis; D051379:Mice; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology* / Q000648:ultrastructure; D011247:Pregnancy; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D019289:Pyruvic Acid / Q000008:administration & dosage*; D013997:Time Factors
chemical_list: D003470:Culture Media; D019253:Proto-Oncogene Proteins c-bcl-2; C052617:Bcl2 protein, mouse; D000431:Ethanol; D019289:Pyruvic Acid; D005978:Glutathione