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Developmental potential of prepubertal mouse oocytes is compromised due mainly to their impaired synthesis of glutathione.

Jiao GZ, Cao XY, Cui W, Lian HY, Miao YL, Wu XF, Han D, Tan JH - PLoS ONE (2013)

Bottom Line: Although oocytes from prepubertal animals are found less competent than oocytes from adults, the underlying mechanisms are poorly understood.Whereas reactive oxygen species (ROS) levels increased, Ca(2+) storage decreased significantly in prepubertal oocytes.Maternal eCG priming improved all the parameters and eliminated the age difference.

View Article: PubMed Central - PubMed

Affiliation: College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai-an City, People's Republic of China.

ABSTRACT
Although oocytes from prepubertal animals are found less competent than oocytes from adults, the underlying mechanisms are poorly understood. Using the mouse oocyte model, this paper has tested the hypothesis that the developmental potential of prepubertal oocytes is compromised due mainly to their impaired potential for glutathione synthesis. Oocytes from prepubertal and adult mice, primed with or without eCG, were matured in vitro and assessed for glutathione synthesis potential, oxidative stress, Ca(2+) reserves, fertilization and in vitro development potential. In unprimed mice, abilities for glutathione synthesis, activation, male pronuclear formation, blastocyst formation, cortical granule migration and polyspermic block were all compromised significantly in prepubertal compared to adult oocytes. Cysteamine and cystine supplementation to maturation medium significantly promoted oocyte glutathione synthesis and blastocyst development but difference due to maternal age remained. Whereas reactive oxygen species (ROS) levels increased, Ca(2+) storage decreased significantly in prepubertal oocytes. Levels of both catalytic and modifier subunits of the γ-glutamylcysteine ligase were significantly lower in prepubertal than in adult oocytes. Maternal eCG priming improved all the parameters and eliminated the age difference. Together, the results have confirmed our hypothesis by showing that prepubertal oocytes have a decreased ability to synthesize glutathione leading to an impaired potential to reduce ROS and to form male pronuclei and blastocysts. The resulting oxidative stress decreases the intracellular Ca(2+) store resulting in impaired activation at fertilization, and damages the microfilament network, which affects cortical granule redistribution leading to polyspermy.

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Relative levels of catalytic subunit (GCLc) and modifier subunit (GCLm) of the γ-glutamylcysteine ligase in mouse GV-stage oocytes recovered from unstimulated (eCG−) or eCG-primed (eCG+) prepubertal (Prepb) or adult mice.Results from Western blotting. Each treatment was repeated 3 times and each replicate contained about 500 oocytes. a–c: Values without a common letter above their bars differ (P<0.05) within panels.
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pone-0058018-g006: Relative levels of catalytic subunit (GCLc) and modifier subunit (GCLm) of the γ-glutamylcysteine ligase in mouse GV-stage oocytes recovered from unstimulated (eCG−) or eCG-primed (eCG+) prepubertal (Prepb) or adult mice.Results from Western blotting. Each treatment was repeated 3 times and each replicate contained about 500 oocytes. a–c: Values without a common letter above their bars differ (P<0.05) within panels.

Mentions: Oocytes at the GV stage were processed for Western blot analysis to measure protein contents of the GCL subunits. In unstimulated mice, contents of both GCLc and GCLm were significantly lower in prepubertal than in adult oocytes; but their contents increased significantly and the age difference became insignificant after eCG priming (Fig. 6).


Developmental potential of prepubertal mouse oocytes is compromised due mainly to their impaired synthesis of glutathione.

Jiao GZ, Cao XY, Cui W, Lian HY, Miao YL, Wu XF, Han D, Tan JH - PLoS ONE (2013)

Relative levels of catalytic subunit (GCLc) and modifier subunit (GCLm) of the γ-glutamylcysteine ligase in mouse GV-stage oocytes recovered from unstimulated (eCG−) or eCG-primed (eCG+) prepubertal (Prepb) or adult mice.Results from Western blotting. Each treatment was repeated 3 times and each replicate contained about 500 oocytes. a–c: Values without a common letter above their bars differ (P<0.05) within panels.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585726&req=5

pone-0058018-g006: Relative levels of catalytic subunit (GCLc) and modifier subunit (GCLm) of the γ-glutamylcysteine ligase in mouse GV-stage oocytes recovered from unstimulated (eCG−) or eCG-primed (eCG+) prepubertal (Prepb) or adult mice.Results from Western blotting. Each treatment was repeated 3 times and each replicate contained about 500 oocytes. a–c: Values without a common letter above their bars differ (P<0.05) within panels.
Mentions: Oocytes at the GV stage were processed for Western blot analysis to measure protein contents of the GCL subunits. In unstimulated mice, contents of both GCLc and GCLm were significantly lower in prepubertal than in adult oocytes; but their contents increased significantly and the age difference became insignificant after eCG priming (Fig. 6).

Bottom Line: Although oocytes from prepubertal animals are found less competent than oocytes from adults, the underlying mechanisms are poorly understood.Whereas reactive oxygen species (ROS) levels increased, Ca(2+) storage decreased significantly in prepubertal oocytes.Maternal eCG priming improved all the parameters and eliminated the age difference.

View Article: PubMed Central - PubMed

Affiliation: College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai-an City, People's Republic of China.

ABSTRACT
Although oocytes from prepubertal animals are found less competent than oocytes from adults, the underlying mechanisms are poorly understood. Using the mouse oocyte model, this paper has tested the hypothesis that the developmental potential of prepubertal oocytes is compromised due mainly to their impaired potential for glutathione synthesis. Oocytes from prepubertal and adult mice, primed with or without eCG, were matured in vitro and assessed for glutathione synthesis potential, oxidative stress, Ca(2+) reserves, fertilization and in vitro development potential. In unprimed mice, abilities for glutathione synthesis, activation, male pronuclear formation, blastocyst formation, cortical granule migration and polyspermic block were all compromised significantly in prepubertal compared to adult oocytes. Cysteamine and cystine supplementation to maturation medium significantly promoted oocyte glutathione synthesis and blastocyst development but difference due to maternal age remained. Whereas reactive oxygen species (ROS) levels increased, Ca(2+) storage decreased significantly in prepubertal oocytes. Levels of both catalytic and modifier subunits of the γ-glutamylcysteine ligase were significantly lower in prepubertal than in adult oocytes. Maternal eCG priming improved all the parameters and eliminated the age difference. Together, the results have confirmed our hypothesis by showing that prepubertal oocytes have a decreased ability to synthesize glutathione leading to an impaired potential to reduce ROS and to form male pronuclei and blastocysts. The resulting oxidative stress decreases the intracellular Ca(2+) store resulting in impaired activation at fertilization, and damages the microfilament network, which affects cortical granule redistribution leading to polyspermy.

Show MeSH
Related in: MedlinePlus