Cortez Jenin V, Hardwicke Kylie, Méndez-Calderón Carlos E, Grupen Christopher G
Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Camden, NSW 2570, Australia.
Catalina Equine Reproduction Centre, North Richmond, NSW 2754, Australia.
Animals (Basel). 2025 Jul 3;15(13):1961. doi: 10.3390/ani15131961.
The asynchrony of cytoplasmic and nuclear maturation in cumulus-oocyte complexes (COCs) due to prematurely declining concentrations of cyclic adenosine monophosphate (cAMP) has been shown to result in reduced oocyte developmental competence. The objective of this study was to evaluate the effect of pre-IVM treatment with cAMP modulators for different durations on the developmental potential of equine oocytes used for cloned embryo production. Collected COCs were transferred to cryovials filled with transport medium at 20-22 °C. Within the cryovials, the COCs were either untreated (Control) for 18 h or treated with 50 µM forskolin and 100 µM 3-isobutyl-1-methylxanthine for the first 4 h (Pre-IVM 4 h) or the entire 18 h (Pre-IVM 18 h). Oocytes were then transferred to maturation medium and incubated for a further 22-24 h at 38.5 °C in 5% CO in air. Somatic cell nuclear transfer embryos were then produced using the meiotically mature oocytes and donor cells from six different fibroblast cell lines. The rates of maturation and embryo development did not differ significantly between the groups, though blastocyst formation tended to be inferior in the Pre-IVM 4 h group compared with the Control group ( = 0.06). Of 67 blastocysts produced, 23 were transferred to recipient mares on Day 4 or 5 post-ovulation. Regarding the pregnancy outcomes, no significant differences were found between the groups, and four viable foals were born, each derived from a different donor cell line. The findings expand on those from previous evaluations of this biphasic IVM system, and indicate that the cAMP-modulating treatments exert limited effects under the pre-IVM conditions used here.
卵丘-卵母细胞复合体（COCs）中由于环磷酸腺苷（cAMP）浓度过早下降导致的细胞质和细胞核成熟不同步，已被证明会导致卵母细胞发育能力降低。本研究的目的是评估用cAMP调节剂进行不同时长的体外成熟前（Pre-IVM）处理对用于克隆胚胎生产的马卵母细胞发育潜力的影响。收集的COCs在20-22°C下转移到装有运输培养基的冻存管中。在冻存管内，COCs要么未经处理（对照组）18小时，要么在前4小时（Pre-IVM 4小时）或整个18小时（Pre-IVM 18小时）用50μM福斯高林和100μM 3-异丁基-1-甲基黄嘌呤处理。然后将卵母细胞转移到成熟培养基中，在38.5°C、5%二氧化碳的空气中再孵育22-24小时。然后使用减数分裂成熟的卵母细胞和来自六种不同成纤维细胞系的供体细胞生产体细胞核移植胚胎。各组之间的成熟率和胚胎发育率没有显著差异，尽管与对照组相比，Pre-IVM 4小时组的囊胚形成率往往较低（P = 0.06）。在产生的67个囊胚中，23个在排卵后第4天或第5天转移到受体母马体内。关于妊娠结局，各组之间未发现显著差异，共出生了4匹活驹，每匹来自不同的供体细胞系。这些发现扩展了先前对这种双相体外成熟系统评估的结果，并表明在此处使用的体外成熟前条件下，cAMP调节处理的效果有限。
