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Updated: Jul 3, 2026
Vitrification of In Vitro Matured Oocytes Collected from Adult and Prepubertal Ovaries in Sheep
Published on: July 10, 2021
Caffeine treatment prevents age-related changes in ovine oocytes and increases cell numbers in blastocysts produced
Joon-Hee Lee1, Keith H S Campbell
1Animal Development and Biotechnology Group, Division of Animal Physiology, School of Biosciences, The University of Nottingham, Sutton Bonington, Loughborough, Leicestershire, United Kingdom.
Abstract:
Maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK) are key regulators of both meiotic and mitotic cycles. Oocytes arrested at metaphase of the second meiotic division (MII) contain high levels of both kinases; however, these activities decline with age. Caffeine (an inhibitor of Myt1/Wee1 activity) can increase MPF and MAPK activities in ovine oocytes; however, the effects of caffeine treatment on the activation, nuclear configuration and developmental potential of ovine SC nuclear transfer (SCNT) embryos were unknown. We examined the effects of aging and caffeine treatment on MPF and MAPK activities, activation, development, and nuclear remodeling of SCNT embryos. Both kinases reached maximum activities at 24-h postonset of maturation (hpm) and then decreased with time. The decline in MPF activity occurred rapidly, whereas MAPK activity declined more slowly. Caffeine treatment (10.0 mM) of aging oocytes prevented the decline in activities associated with both kinases and prevented the acquisition of activation competence by a single activation stimulus. However, treatment of aged oocytes with caffeine could not increase kinase activities or reverse the acquisition of activation competence. Enucleation did not affect kinase activities, but caffeine treatment significantly increased both. Caffeine treatment did not affect the decline in MPF or MAPK activities following activation or significantly affect development of parthenogenetically activated oocytes. When SCNT reconstructed embryos were treated with caffeine following fusion, no increase in the frequency of development to blastocyst was observed; however, a significant increase in the occurrence of nuclear envelope break-down (NEBD) and an increase in total cell numbers occurred.
Insights
Caffeine prevents age-related decline in maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK) in ovine oocytes, but does not restore activation competence or improve SCNT embryo development to blastocyst.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Cell Signaling
Background:
- Maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK) are crucial for cell cycle regulation.
- Oocyte aging leads to decreased MPF and MAPK activity, impacting developmental potential.
- Caffeine is known to inhibit Myt1/Wee1 activity and can influence kinase levels in oocytes.
Purpose of the Study:
- To investigate the effects of aging and caffeine treatment on MPF and MAPK activities in ovine oocytes.
- To examine the impact of caffeine on the activation, nuclear configuration, and developmental potential of ovine somatic cell nuclear transfer (SCNT) embryos.
- To determine if caffeine can reverse age-related declines in oocyte competence.
Main Methods:
- Oocytes were matured, and MPF and MAPK activities were measured at various time points.
- Ovine oocytes were treated with caffeine (10.0 mM) during maturation.
- SCNT embryos were reconstructed and cultured, with some treated with caffeine post-fusion.
- Nuclear remodeling events, including nuclear envelope breakdown (NEBD), were assessed.
Main Results:
- MPF and MAPK activities peaked at 24 hours post-maturation and subsequently declined, with MPF decreasing faster than MAPK.
- Caffeine treatment prevented the age-related decline in MPF and MAPK activities and prevented the acquisition of activation competence.
- Caffeine treatment did not restore activation competence in aged oocytes or improve the developmental rate of SCNT embryos to blastocyst.
- Caffeine treatment of SCNT embryos post-fusion increased NEBD and total cell numbers but did not enhance blastocyst formation.
Conclusions:
- Caffeine can maintain MPF and MAPK activity in aging ovine oocytes but does not reverse the loss of activation competence.
- While caffeine influences nuclear remodeling events like NEBD in SCNT embryos, it does not improve their developmental potential to the blastocyst stage.
