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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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Effects of maternal puberty and eCG treatment on CGs distribution of mouse oocytes following in vitro maturation.A to C are confocal images. Image A is an oocyte with complete migration of CGs, whereas images B and C are oocytes with incomplete CGs migration. Oocytes were observed under a laser confocal microscope following immunostaining with Hoechst 33342 for DNA and with FITC-LCA for CGs. Scale bar is 20 µm. D is a graph showing percentages of oocytes with incomplete CGs migration in prepubertal (Prepb) or adult mice primed with (eCG+) or without eCG (eCG−). Each treatment was repeated 4–5 times and each replicate contained 25–35 oocytes. a–c: Values without a common letter above their bars differ (P<0.05).
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pone-0058018-g001: Effects of maternal puberty and eCG treatment on CGs distribution of mouse oocytes following in vitro maturation.A to C are confocal images. Image A is an oocyte with complete migration of CGs, whereas images B and C are oocytes with incomplete CGs migration. Oocytes were observed under a laser confocal microscope following immunostaining with Hoechst 33342 for DNA and with FITC-LCA for CGs. Scale bar is 20 µm. D is a graph showing percentages of oocytes with incomplete CGs migration in prepubertal (Prepb) or adult mice primed with (eCG+) or without eCG (eCG−). Each treatment was repeated 4–5 times and each replicate contained 25–35 oocytes. a–c: Values without a common letter above their bars differ (P<0.05).

Mentions: In vitro matured oocytes were observed for CGs distribution at the end of maturation culture. Two types of CGs distribution were observed: (a) complete migration with all the CGs located in the egg cortex forming a monolayer beneath the plasma membrane (Fig. 1A) and (b) incomplete migration with some CGs having migrated into the cortex but still many left in the inner ooplasm (Fig. 1B and C). In unprimed mice, the percentage of oocytes with incomplete CGs migration was significantly higher in prepubertal than in adult mice (Fig. 1D). Treatment with eCG significantly decreased the number of oocytes with incomplete CGs migration in both prepubertal and adult mice and eliminated the age difference.


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)

Effects of maternal puberty and eCG treatment on CGs distribution of mouse oocytes following in vitro maturation.A to C are confocal images. Image A is an oocyte with complete migration of CGs, whereas images B and C are oocytes with incomplete CGs migration. Oocytes were observed under a laser confocal microscope following immunostaining with Hoechst 33342 for DNA and with FITC-LCA for CGs. Scale bar is 20 µm. D is a graph showing percentages of oocytes with incomplete CGs migration in prepubertal (Prepb) or adult mice primed with (eCG+) or without eCG (eCG−). Each treatment was repeated 4–5 times and each replicate contained 25–35 oocytes. a–c: Values without a common letter above their bars differ (P<0.05).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0058018-g001: Effects of maternal puberty and eCG treatment on CGs distribution of mouse oocytes following in vitro maturation.A to C are confocal images. Image A is an oocyte with complete migration of CGs, whereas images B and C are oocytes with incomplete CGs migration. Oocytes were observed under a laser confocal microscope following immunostaining with Hoechst 33342 for DNA and with FITC-LCA for CGs. Scale bar is 20 µm. D is a graph showing percentages of oocytes with incomplete CGs migration in prepubertal (Prepb) or adult mice primed with (eCG+) or without eCG (eCG−). Each treatment was repeated 4–5 times and each replicate contained 25–35 oocytes. a–c: Values without a common letter above their bars differ (P<0.05).
Mentions: In vitro matured oocytes were observed for CGs distribution at the end of maturation culture. Two types of CGs distribution were observed: (a) complete migration with all the CGs located in the egg cortex forming a monolayer beneath the plasma membrane (Fig. 1A) and (b) incomplete migration with some CGs having migrated into the cortex but still many left in the inner ooplasm (Fig. 1B and C). In unprimed mice, the percentage of oocytes with incomplete CGs migration was significantly higher in prepubertal than in adult mice (Fig. 1D). Treatment with eCG significantly decreased the number of oocytes with incomplete CGs migration in both prepubertal and adult mice and eliminated the age difference.

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