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Optimized protocols of meiotic arrest maintenance improved in vitro maturation of ovine oocytes
Nan He1, Yong-Qi Wang1, Lin Jiang1
1College of Animal Science and Technology, Shandong Agricultural University, Tai'an City 271018, P. R. China.
Context:
The developmental potential (DP) of in vitro-matured (IVM) oocytes is considerably lower than that of in vivo-matured oocytes, primarily owing to the premature resumption of meiosis without adequate cytoplasmic maturation during IVM. Evidence indicates that meiotic arrest maintenance (MAM) during IVM significantly enhances oocyte DP. However, studies on ovine oocytes remain scarce.
Aims:
To optimize MAM protocols for improving maturation of ovine oocytes.
Methods:
Ovine oocytes collected from abattoir-derived ovaries were subjected to MAM culture for 24 h, followed by assessment of MAM efficiency and oocyte DP.
Key Results:
When used individually, roscovitine (RSC), db-cAMP, and U0126 showed suboptimal MAM efficiency. However, their combined application at substantially reduced concentrations yielded markedly improved outcomes. A combination of 12.5 μM RSC, 1000 μM db-cAMP, and 10 μM U0126 achieved high MAM efficiency, and when MAM lasted for 18 h, it resulted in significantly higher oocyte DP than in control oocytes matured without MAM. Furthermore, oxidative stress was detected during MAM, and the addition of antioxidants during the 24 h MAM period enhanced oocyte DP beyond that of non-MAM controls.
Conclusions:
High MAM efficiency and improved oocyte DP were achieved using a combination of RSC, db-cAMP, and U0126 at reduced concentrations, indicating that meiotic arrest in ovine oocytes is regulated through multiple signaling pathways. Antioxidant supplementation is essential for successful extended MAM.
Implications:
Findings are critical for refining MAM and IVM protocols and for advancing understanding of mechanisms governing oocyte meiotic arrest and maturation.
Insights
Optimizing meiotic arrest maintenance (MAM) in ovine oocytes using a combination of roscovitine, db-cAMP, and U0126 significantly improved developmental potential. Antioxidants are crucial for extended MAM protocols in sheep oocytes.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Oocyte Maturation
Background:
- In vitro-matured (IVM) oocytes have lower developmental potential (DP) than in vivo-matured oocytes due to premature meiosis resumption.
- Meiotic arrest maintenance (MAM) during IVM enhances oocyte DP, but studies in ovine oocytes are limited.
Purpose of the Study:
- To optimize MAM protocols for improving ovine oocyte maturation and developmental potential.
- Investigate the role of signaling pathways and oxidative stress in ovine oocyte meiotic arrest.
Main Methods:
- Ovine oocytes were cultured with MAM for 24 hours.
- Assessed MAM efficiency and oocyte DP using combinations of roscovitine (RSC), db-cAMP, and U0126 at reduced concentrations.
- Evaluated the impact of antioxidant supplementation during MAM.
Main Results:
- Combined application of RSC, db-cAMP, and U0126 at 12.5 μM, 1000 μM, and 10 μM respectively, achieved high MAM efficiency.
- An 18-hour MAM period resulted in significantly higher oocyte DP compared to controls.
- Antioxidant addition during MAM enhanced oocyte DP, mitigating oxidative stress.
Conclusions:
- A combination of RSC, db-cAMP, and U0126 at reduced concentrations effectively improves ovine oocyte DP.
- Ovine oocyte meiotic arrest involves multiple signaling pathways, and extended MAM requires antioxidant support.
- Findings are crucial for refining IVM protocols and understanding oocyte maturation mechanisms.
