Effect of glucose and pyruvate on nuclear and cytoplasmic maturation of porcine oocytes in a chemically defined medium.
The objective was to examine potential roles of glucose and pyruvate in nuclear and cytoplasmic maturation of porcine oocytes. Oocyte-cumulus complexes (OCC), derived from 3 to 6mm follicles, were cultured in a chemically defined medium (pyruvate-free mNCSU37-PVA), with or without 5.55 mM glucose, during in vitro maturation (IVM); in the absence of glucose, germinal vesicle breakdown (GVBD) and nuclear maturation were prevented (P<0.05). Subsequently, OCC were cultured for IVM in glucose-containing mNCSU37-PVA supplemented with 6-amononicotinamide (6-AN) and diphenyleneiodonium (DPI), inhibitors of the pentose phosphate pathway (PPP); both compounds (>or=10 microM 6-AN and >or=10 nM DPI) inhibited resumption of meiosis (P<0.05). Supplementation of glucose-free maturation medium with increasing concentrations of pyruvate induced resumption of meiosis and increased the incidence of oocytes reaching metaphase-II in a concentration-dependent manner (P<0.05). More mature oocytes were obtained in the presence of pyruvate+glucose (P<0.05). After culture to allow maturation, glutathione content was higher in oocytes cultured in the presence of pyruvate alone than in those cultured in glucose alone; inclusion of 6-AN abolished responses to pyruvate (P<0.05). In conclusion, both glucose and pyruvate played a critical role in the release of porcine oocytes from arrest at the GV-I stage, probably through the PPP, whereas supplementation with pyruvate improved cytoplasmic maturation, as determined by oocyte glutathione content.
Funahashi
H
H
Department of Animal Science, Okayama University, 1-1-1 Tsushima-Naka, Okayama 700-8530, Japan. hirofun@cc.okayama-u.ac.jp
Koike
T
T
Sakai
R
R
D000818:Animals; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D046508:Culture Techniques; D047108:Embryonic Development / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D008540:Meiosis / Q000187:drug effects; D009865:Oocytes / Q000187:drug effects* / Q000254:growth & development*; D019289:Pyruvic Acid / Q000494:pharmacology*; D013552:Swine / Q000502:physiology*
D003470:Culture Media; D019289:Pyruvic Acid; D005978:Glutathione; D005947:Glucose