535. THE EFFECT OF ALTERING GLUCOSE LEVELS DURING COLLECTION AND MATURATION OF MOUSE OOCYTES ON SUBSEQUENT DEVELOPMENTAL COMPETENCE

Abstract

The preconception environment is known to influence oocyte developmental competence. In particular, hyperglycaemic conditions during cumulus-oocyte complex (COC) maturation result in decreased oocyte quality. This is, in part, due to perturbations in O-linked glycosylation in the cumulus cells. In embryos, even a brief exposure to glucose during early cleavage can have significant impact on O-linked glycosylation and further development. The aim of this study was to determine the effect of altering glucose concentrations during the collection and maturation phases of COCs on oocyte developmental competence. COCs were collected and matured for 17h at 37°C in 6% CO₂ with 0 or 10mM glucose in a 2 x 2 factorial design. A fifth group used standard concentrations of 0.5mM and 5.55mM glucose in the collection and maturation media respectively. Following maturation, oocytes were inseminated and cultured to the blastocyst stage. The average time for collection was 1 h. COCs exposed to 0mM glucose during collection and 10mM glucose during maturation had the greatest cumulus expansion despite no change in the proportion of COCs completing nuclear maturation. However, this same treatment group resulted in significantly lower blastocyst production than the control group (8.4% vs. 25.0%, P<0.05). These results show that glucose concentration in collection medium has a significant influence on maturation indices and oocyte developmental competence, as determined by blastocyst development rates. Our data further supports the concept that the conditions used for the collection of oocytes can have profound effects on subsequent development. We intend to investigate if these effects are related to perturbations in cumulus cell O-linked glycosylation.