Alterations of Intraembryonic Metabolites in Preimplantation Mouse Embryos Exposed to Elevated Concentrations of Glucose: A Metabolic Explanation for the Developmental Retardation Seen in Preimplantation Embryos from Diabetic Animals1

Abstract

Preimplantation mouse embryos exposed to hyperglycemia, whether in vivo or in vitro, experience delayed development from the 2-cell to blastocyst stage. By comparing metabolites from embryos exposed to high vs. normal glucose conditions, a metabolic explanation for the delayed growth pattern was sought. Fertilized 1-cell embryos obtained from superovulated B5 x CBA F1 mice were cultured for 96 h in medium containing 2.8 mM glucose (C) or in medium with added glucose to give 10 mM, 30 mM, or 52 mM glucose (HG). After incubation, each embryo was quick-frozen and freeze-dried. Metabolites were assayed by the ultramicrofluorometric technique and enzymatic cycling to obtain measurable levels in single embryos. Embryos cultured in HG exhibited 7-fold higher intracellular glucose levels than those cultured in C (C: 2.25 +/- 0.6 vs. HG: 16.61 +/- 2.4 mmol/kg wet weight; p < 0.001; C, n = 9; HG, n = 16). This accumulation of glucose was dose-related and stage-dependent. Citrate (C: 1.07 +/- 0.14 vs. HG: 1.98 +/- 0.12; p < 0.001), sorbitol (C: 0.41 +/- 0.06 vs. HG: 0.57 +/- 0.03; p < 0.01), malate (C: 0.81 +/- 0.13 vs. HG: 1.72 +/- 0.17; p < 0.001), and fructose (C: 2.1 +/- 0.3 vs. HG: 5.3 +/- 0.6; p < 0.001) were all significantly higher in HG. Also, these metabolites were highest in the most delayed embryos. Glycogen and 6-phosphogluconate levels were not significantly different. In conclusion, intraembryonic levels of glucose, and polyol pathway and Krebs cycle metabolites are elevated and correspond to the degree of developmental delay. These findings suggest that a metabolic abnormality may be responsible for retarded development experienced by embryos exposed to high glucose.

Role of glucose in cloned mouse embryo development

“…ATP was measured in each embryo individually as described for embryos (9). Similarly, intraembryonic glycogen levels were measured in single embryos, as reported elsewhere (31). Adenyl kinase and glycogen synthase assays have been described previously (36).…”

Glukose, Glukosetransporter und Insulin

“…Aus der Arbeitsgruppe um Tom Fleming (Southampton) liegen tierexperimentelle Ergebnisse vor [28],die einen Zusammenhang zwischen der maternalen Ernährung während der kurzen Zeitspanne der Präimplantationsphase bei der Ratte und der späteren Ausbildung von Bluthochdruck bei den Nachkommen zeigen (s. weiter unten). Diese Untersuchungen ergänzen Befunde,die in sog.diabetischen Tiermodellen (Ratte: [14,42]; Maus: [10]) und in In-vitro-Untersuchungen [11,34,35] gewonnen worden waren,in denen Präim-plantationsembryonen mit hohen der assistierten Reproduktion (ART) in der Medizin,biotechnologische Verfahren in der Veterinärmedizin und die Stammzelltechnologie wissenschaftlich fundierte Ergebnisse über die kurz-und langfristigen Implikationen der Glukose-und Insulin-/IGF-Exposition während der Präim-plantationsperiode bzw.von Blastozystenzellen.…”

Oxidant release is dramatically increased by elevated glucose concentrations in neutrophils from pregnant women

“…Cellular events associated with congenital malformations of offspring occur early in pregnancy. Maternal diabetes in rats and mice has shown impaired embryonic growth at the pre-implantation stage [12] While other diabetesrelated factors such as triglycerides and branched amino acid chains may influence the outcome of pregnancy [13], it has been suggested that the primary teratogen in diabetic pregnancy is hyperglycemia [14][15][16][17]. A number of teratological pathways in embryonic tissue have been identified, including variations in metabolism of inositol, arachidonic acid and reactive oxygen species (ROS) [18][19][20].…”