Reproductive Medicine Unit, Gynecology, Obstetrics, Reproduction and Neonatology Department, Unidade Local de Saúde de Coimbra, Praceta, R. Prof. Mota Pinto, Coimbra, 3004-561, Portugal.
Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, Celas, Coimbra, 3000-548, Portugal.
J Assist Reprod Genet. 2024 Aug;41(8):1997-2009. doi: 10.1007/s10815-024-03151-4. Epub 2024 Jun 1.
There are no clinical treatments to prevent/revert age-related alterations associated with oocyte competence decline in the context of advanced maternal age. Those alterations have been attributed to oxidative stress and mitochondrial dysfunction. Our study aimed to test the hypothesis that in vitro maturation (IVM) medium supplementation with antioxidants (resveratrol or phloretin) may revert age-related oocyte competence decline.
Bovine immature oocytes were matured in vitro for 23 h (young) and 30 h (aged). Postovulatory aged oocytes (control group) and embryos obtained after fertilization were examined and compared with oocytes supplemented with either 2 μM of resveratrol or 6 μM phloretin (treatment groups) during IVM.
Aged oocytes had a significantly lower mitochondrial mass and proportion of mitochondrial clustered pattern, lower ooplasmic volume, higher ROS, lower sirtuin-1 protein level, and a lower blastocyst rate in comparison to young oocytes, indicating that postovulatory oocytes have a lower quality and developmental competence, thus validating our experimental model. Supplementation of IVM medium with antioxidants prevented the generation of ROS and restored the active mitochondrial mass and pattern characteristic of younger oocytes. Moreover, sirtuin-1 protein levels were also restored but only following incubation with resveratrol. Despite these findings, the blastocyst rate of treatment groups was not significantly different from the control group, indicating that resveratrol and phloretin could not restore the oocyte competence of postovulatory aged oocytes.
Resveratrol and phloretin can both revert the age-related oxidative stress and mitochondrial dysfunction during postovulatory aging but were insufficient to enhance embryo developmental rates under our experimental conditions.
在高龄产妇的背景下，没有临床治疗方法可以预防/逆转与卵母细胞能力下降相关的与年龄相关的改变。这些改变归因于氧化应激和线粒体功能障碍。我们的研究旨在测试以下假设：在体外成熟（IVM）培养基中添加抗氧化剂（白藜芦醇或根皮苷）可能会逆转与年龄相关的卵母细胞能力下降。
牛未成熟卵母细胞在体外成熟 23 小时（年轻）和 30 小时（年老）。对排卵后年老的卵母细胞（对照组）和受精后获得的胚胎进行检查，并与在 IVM 期间用 2 μM 白藜芦醇或 6 μM 根皮苷（处理组）补充的卵母细胞进行比较。
与年轻卵母细胞相比，年老卵母细胞的线粒体质量和聚集模式比例显著降低，卵质体积降低，ROS 升高，SIRT1 蛋白水平降低，囊胚率降低，表明排卵后的卵母细胞质量和发育能力较低，从而验证了我们的实验模型。在 IVM 培养基中添加抗氧化剂可防止 ROS 的产生，并恢复年轻卵母细胞的活跃线粒体质量和模式。此外，SIRT1 蛋白水平也得到了恢复，但仅在用白藜芦醇孵育后才得到恢复。尽管有这些发现，但处理组的囊胚率与对照组没有显著差异，这表明白藜芦醇和根皮苷不能恢复排卵后年老卵母细胞的卵母细胞能力。
白藜芦醇和根皮苷均可逆转排卵后衰老过程中与年龄相关的氧化应激和线粒体功能障碍，但在我们的实验条件下，不足以提高胚胎发育率。
