Abstract
Simple SummaryOocyte in vitro maturation has massive potential for the generation of great numbers of embryos for research and for the application of assisted reproductive technologies, such as in vitro embryo production. However, the developmental ability of in vitro matured oocytes is lower than those matured in vivo. Here, incubating the oocytes with cAMP modulating agents for two hours before in vitro maturation decreased oocyte DNA damage and increased the number of embryos generated after in vitro fertilization. The present findings could help to develop new methods to improve the quality and developmental potential of in vitro matured oocytes.To date, the underlying mechanisms by which cAMP modulators act during in vitro maturation to improve oocyte developmental competence are poorly understood. Here, we sought to fill this knowledge gap by evaluating the use of phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) and adenylyl cyclase activator forskolin during a culture period of 2 h before in vitro maturation (pre-IVM) on the nuclear and cytoplasmic maturation features in essential organelles, cumulus cells activity, and in vitro developmental potential of sheep oocytes. Results showed that pre-IVM treatment significantly decreased (p < 0.05) the DNA damage of mature oocytes (pre-IVM = 2.08% ± 3.51% vs. control = 20.58% ± 3.51%) and increased (p ≤ 0.05) expanded blastocyst rates compared to the control (from the total of oocytes: pre-IVM = 23.89% ± 1.47% vs. control = 18.22% ± 1.47%, and from the cleaved embryos: pre-IVM = 45.16% ± 1.73% vs. control = 32.88% ± 1.73%). Considering that oocytes are highly vulnerable to the accumulation of DNA damage because of exposure to in vitro culture conditions, our results suggest that the modulation of intra-oocyte cAMP levels with forskolin and IBMX before IVM might afford oocytes a more effective DNA repair mechanism to overcome damage obstacles and ultimately improve developmental competence. This previously unappreciated action of cAMP modulators could help to develop improved methods for assisted reproduction technologies in animal and clinical research.
Highlights
IntroductionOocytes acquire their developmental competence, i.e., the ability to be fertilized and complete pre-implantation embryo development, through the modulation and coordination of 4.0/)
Oocyte DNA Fragmentation Levels Are Affected by cyclic adenosine monophosphate (cAMP) Modulators
Considering that cAMP modulators aim to synchronize nuclear and cytoplasmic maturation events [32], we focused on the underlying cellular mechanisms through which forskolin and IBMX could influence oocyte quality and developmental competence in sheep
Summary
Oocytes acquire their developmental competence, i.e., the ability to be fertilized and complete pre-implantation embryo development, through the modulation and coordination of 4.0/). Both nuclear and cytoplasmic events [3]. The cGMP produced diffuses into the oocyte through gap junctions and inhibits the activity of phosphodiesterase 3A (PDE3A) [7], an oocyte-specific phosphodiesterase that degrades cyclic adenosine monophosphate (cAMP) [8]. This intricate pathway maintains high basal cAMP levels, thereby sustaining meiotic arrest [9]. A series of complex programmed events, including the redistribution of cytoplasmic organelles, transcription of mRNAs, and the modification of proteins, occur in oocytes to complete cytoplasm maturation [11]
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