Requirement for glucose in ligand-stimulated meiotic maturation of cumulus cell-enclosed mouse oocytes

Abstract

In this study, the effect of different energy sources used in Eagle's minimum essential medium on the meiotic maturation of mouse oocytes in culture was examined. The effects of glucose (5.5 mmol 1(-1)), pyruvate (0.23 mmol 1(-1)) and glutamine (2 mmol 1(-1)) in different combinations were tested on the maturation of denuded oocytes in the presence or absence of 300 mumol dibutyryl cAMP 1(-1) during 17-18 h of culture. In the absence of cyclic nucleotide, only oocytes from those groups containing pyruvate resumed maturation at a high frequency (99-100% germinal vesicle breakdown); all other combinations resulted in < or = 54% germinal vesicle breakdown. When dibutyryl cAMP was introduced, all pyruvate-containing groups exhibited maturation frequencies of about 50%, whereas maturation in all other groups was negligible (< or = 10% GVB). Pyruvate was also important for the maintenance of viability in denuded oocytes (> or = 86% viability in pyruvate-containing medium; < or = 35% viability in pyruvate-free groups). When cumulus cell-enclosed oocytes were cultured in medium without inhibitor, all combinations of energy substrates supported high frequencies of maturation (> or = 89% germinal vesicle breakdown) and viability (> or = 91%). The addition of dibutyryl cAMP resulted in inhibition of meiotic maturation (5-33% germinal vesicle breakdown) in all cultures except the pyruvate-alone group (97% germinal vesicle breakdown). Viability in cumulus cell-enclosed oocytes was greatest when two or more energy substrates were present in the medium. Follicle-stimulating hormone (FSH) produced a stimulation of meiotic maturation in all cultures of meiotically arrested cumulus cell-enclosed oocytes, but maximal induction of germinal vesicle breakdown was dependent upon D-glucose. Concanavalin A (ConA)-induced meiotic maturation was also dependent upon D-glucose. Uptake and metabolism of D-glucose by the cumulus cells is important in mediating the stimulatory effects of these ligands on oocyte maturation because (1) both FSH and ConA stimulated uptake of D-glucose and 2-deoxyglucose but not 3-O-methylglucose; (2) phloretin prevented the stimulatory action of FSH and ConA on germinal vesicle breakdown at a concentration that suppressed ligand-induced uptake of D-glucose; (3) 2-deoxyglucose, a hexose that suppresses glycolysis, prevented the induction of meiotic maturation by FSH and ConA and (4) D-mannose, a glycolysable sugar, was as effective as D-glucose in supporting the ligand effects.(ABSTRACT TRUNCATED AT 400 WORDS)

Metabolism throughout follicle and oocyte development in mammals

“…Furthermore, it is well established that glucose is required to support FSH-dependent cumulus expansion and oocyte maturation (Fagbohun and Downs, 1992), while denuded mouse oocytes require pyruvate or oxaloacetate to sustain spontaneous nuclear maturation (Biggers et al, 1967;Downs and Hudson, 2000). The oocyte energetic requirements for resumption of meiosis appear to be met by an increase in oxidative metabolism around the time of GVBD; pyruvate being used as the main substrate, and supplemented by glutamine and glycine which can feed into the TCA cycle (Zuelke and Brackett, 1993;Rieger and Loskutoff, 1994;Downs et al, 2002;Harris et al, 2007).…”

Differing roles of pyruvate dehydrogenase kinases during mouse oocyte maturation

“…Throughout the period of oocyte growth, pyruvate and oxygen consumption is markedly increased (Harris et al, 2009). Fully-grown oocytes have limited capacity to utilize glucose (Biggers et al, 1967;Saito et al, 1994;Zuelke and Brackett, 1992); instead, glucose first needs to be transferred to granulosa cells and then metabolized into pyruvate to support oocyte maturation (Eppig, 1976;Fagbohun and Downs, 1992). Oocyte-specific deletion of mouse PDHA1, the gene encoding the PDHE1α subunit of the pyruvate dehydrogenase (PDH) complex, results in compromised energetic status and meiotic defects in mouse oocytes (Johnson et al, 2007), further highlighting the importance of pyruvate metabolism during oocyte development.…”

Physiological Changes in Oocyte-Cumulus Cell Complexes from Diabetic Mice that Potentially Influence Meiotic Regulation1

“…Glucose is required for hormone-induced maturation [16], but under the appropriate culture conditions, elevated levels of glucose have been shown to suppress maturation [14,17,18]. Although cumulus cells are very active glycolytically [19][20][21], this pathway does not appear to be vital for meiotic induction [22]; however, it may play a role in spontaneous maturation [18].…”