Development of glucose utilization studied in single oocytes and preimplantation embryos from mice.
Superovulated mouse oocytes and embryos were isolated and incubated with nontracer concentrations of 2-deoxyglucose, an analog of glucose, which is transported into the cells by glucose transporter and phosphorylated by hexokinase to 2-deoxyglucose 6-phosphate; it is not rapidly metabolized further, and accumulates in the cytosol. Using our non-radiometric and enzymatic microassay method, we determined 2-deoxyglucose and 2-deoxyglucose 6-phosphate amounts in individual oocytes and preimplantation embryos after the incubation. Hexokinase activity increased continuously and exponentially during development from follicular oocytes to blastocysts. Endogenous glucose and glucose 6-phosphate decreased precipitously from follicular oocytes to unfertilized and ovulated oocytes. Fertilization induced rapid increases in glucose and glucose 6-phosphate concentrations, which increased exponentially thereafter during embryonic development. 2-Deoxyglucose incorporation and 2-deoxyglucose 6-phosphate formation were undetectable in unfertilized oocytes. However, when cumulus-oocyte complexes were incubated with 2-deoxyglucose, 2-deoxyglucose was incorporated into cumulus cells surrounding follicular oocytes and transported via the gap junctions into the follicular oocytes. Fertilization triggered facilitative 2-deoxyglucose transport in one-cell embryos, and the capacities of 2-deoxyglucose incorporation and 2-deoxyglucose 6-phosphate formation developed along with the maturation of preimplantation embryos.
Saito
T
T
Department of Obstetrics and Gynecology, Yamagata University School of Medicine, Japan.
Hiroi
M
M
Kato
T
T
D000818:Animals; D001692:Biological Transport; D001755:Blastocyst / Q000378:metabolism*; D003847:Deoxyglucose / Q000378:metabolism*; D005260:Female; D019298:Glucose-6-Phosphate / Q000031:analogs & derivatives*; D005958:Glucosephosphates / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D009865:Oocytes / Q000378:metabolism*; D013480:Superovulation
D005958:Glucosephosphates; C015785:2-deoxyglucose-6-phosphate; D019298:Glucose-6-Phosphate; D003847:Deoxyglucose; D006593:Hexokinase