The Role of Glucose Metabolism on Porcine Oocyte Cytoplasmic Maturation and Its Possible Mechanisms

Abstract

In the present study, we investigated the potential role of glucose and pyruvate in the cytoplasmic maturation of porcine oocytes by investigating the effect of glucose and/or pyruvate supplementation, in the presence or absence of 10% porcine follicular fluid (PFF), on meiotic maturation and subsequent embryo development. In the absence of 10% PFF, without exogenous addition of glucose and pyruvate, the medium seemed unable to support maturation. In the presence of 10% PFF, the addition of 5.6 mM glucose and/or 2 mM pyruvate during in vitro maturation of cumulus enclosed oocytes increased MII oocyte and blastocyst rates. In contrast, oocytes denuded of cumulus cells were not able to take full advantage of the glucose in the medium, as only pyruvate was able to increase the MII rate and the subsequent early embryo developmental ability. Treatment of cumulus enclosed oocytes undergoing maturation with 200 μM dehydroepiandrosterone (DHEA), a pentose phosphate pathway inhibitor, or 2 μM iodoacetate (IA), a glycolysis inhibitor, significantly reduced GHS, intra-oocyte ATP, maternal gene expression, and MPF activity levels. DHEA was also able to increase ROS and reduce the levels of NADPH. Moreover, blastocysts of the DHEA- or IA-treated groups presented higher apoptosis rates and markedly lower cell proliferation cell rates than those of the non-treated group. In conclusion, our results suggest that oocytes maturing in the presence of 10% PFF can make full use of energy sources through glucose metabolism only when they are accompanied by cumulus cells, and that pentose phosphate pathway (PPP) and glycolysis promote porcine oocyte cytoplasmic maturation by supplying energy, regulating maternal gene expression, and controlling MPF activity.

Response of Bovine Cumulus–Oocytes Complexes to Energy Pathway Inhibition during In Vitro Maturation

“…Additionally, inhibition of PPP increased reactive oxygen species (ROS) and reduced the level of nicotinamide adenine dinucleotide phosphate (NADPH). Described modifications during IVM affected the quality of the nascent porcine embryos, where higher apoptosis and cell proliferation rates were observed [10]. Similar effects were described regarding mouse oocytes (delayed meiosis resumption, GSH, and ATP reduction) and embryos (lower blastocyst rate) [11].…”

The Mechanisms of Improving IVF Outcomes of Liu‐Wei‐Di‐Huang Pill Acting on DOR Patients

“…It was found that glucose and pyruvate affect the cytoplasmic maturation of porcine oocytes through glycolysis. Pyruvate can improve ROS, GSH, ATP, and early embryonic development of MII oocytes and promote the cytoplasmic maturation of pigs by providing energy and reducing oxidative stress [ 37 , 38 ]. In our study, after the treatment of LWDH pill, lactate was downregulated near into the normal level in patients with DOR, which may have an impact on the quality of oocytes.…”

The Effect of Preincubation Time and Myo-inositol Supplementation on the Quality of Mouse MII Oocytes

“…Cell Tracker Blue CMF2HC (4-chloromethyl-6,8-difluoro-7-hydroxycoumarin) fluorochrome was used to analyze the intracellular GSH levels. To do this, at each experiment, 20 MII oocytes from each group were incubated for 30 min at 37° C in phosphate-buffered saline containing 10 μM of Cell Tracker Blue ( 40 , 41 ). Oocytes were washed three times by BSA-supplemented PBS and were placed in cell culture dishes.…”