Oocyte metabolism predicts the development of cat embryos to blastocyst in vitro

Abstract

Current methods for detecting complete oocyte maturation and developmental competence are inadequate. The objectives of this study were to (1) examine the relationship between cat oocyte energy metabolism and development in vitro after fertilization and (2) determine if cumulus cell metabolism could be used to predict development of individual oocytes after fertilization in vitro. The hanging drop method was used to assess metabolism of three different types of cat oocytes: immature (IMO), in vitro matured (IVM), and in vivo matured (IVOM). Stage of oocyte nuclear maturation or developmental competence was assessed after metabolic analysis. Glycolysis and oxidation of glucose, glutamine, palmitate, and lactate increased with the resumption of oocyte meiotic maturation (P<0.05). Pyruvate was the preferred substrate, but uptake was not linked to maturation. IVM oocytes had impaired glucose and palmitate metabolism compared to IVOM oocytes (P<0.05). Oocyte glycolytic activity and oocyte glucose oxidation correlated well with embryo development after insemination in vitro (P<0.05). Furthermore, oocytes that had similar glucose metabolism and that were grouped together for culture on this basis had higher (P<0.05) overall rates of development than oocytes grouped randomly. There was no correlation (P>0.05) between cumulus cell metabolism and individual oocyte development after in vitro fertilization. The data reveal that energy metabolism is linked to oocyte maturation in the cat and that glucose metabolic activity can indicate those oocytes most likely to fertilize and develop in vitro. Measuring cumulus cell metabolism does not accurately predict individual oocyte development after insemination in vitro.

Metabolic markers of developmental competence for in vitro-matured mouse oocytes

“…Higher rates of glycolysis by bovine oocytes denuded at the end of a 24-h maturation period were associated with increased developmental potential (Krisher & Bavister 1999). Blastocyst development in cats was also associated with higher rates of glycolysis by denuded oocytes; however, no correlation was determined between glycolytic activity or glucose oxidation by cumulus cells and subsequent oocyte development (Spindler et al 2000). In the present study, COCs that were able to fertilize consumed more glucose and produced more lactate than the oocytes that failed to fertilize.…”

The pivotal role of glucose metabolism in determining oocyte developmental competence

“…However, numerous groups have demonstrated that despite the low glycolytic activity in the oocyte, there appears to be an important positive relationship between this relatively low glycolytic activity and developmental competence of oocytes (Krisher & Bavister 1999, Spindler et al 2000, Durkin et al 2001, Herrick et al 2006. For example, oocytes derived from pre-pubertal cattle and sheep (which have lower developmental competence) have delayed increases in glycolytic activity during maturation compared to oocytes derived from adult animals (higher developmental competence), with the rate of glucose metabolism in adult oocytes constantly increasing over a 24-h period, compared to increases in activity at the end of maturation in prepubertal derived oocytes (O'Brien et al 1996, Steeves & Gardner 1999.…”

Improved felid embryo development by group culture is maintained with heterospecific companions

“…Recently, we have demonstrated that the quality of cat embryos can be predicted from the metabolic pattern of the source oocytes [53] as in cattle [54]. Metabolic selection of individual companion embryos is labor intensive and may not be available at the site of gamete rescue.…”

“…Metabolic selection of individual companion embryos is labor intensive and may not be available at the site of gamete rescue. As oocyte metabolism is linked to overall developmental potential [53,54], including time to first cleavage [55], we suggest that selection of high quality cat embryos can also be performed by assessing time to first cleavage as in cattle [56] and humans [57].…”