Graduate School of Medicine and Veterinary Medicine, University of Miyazaki, Miyazaki 889-2192, Japan.
Department of Veterinary Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan.
J Reprod Dev. 2022 Aug 1;68(4):271-277. doi: 10.1262/jrd.2021-145. Epub 2022 Jun 15.
High summer temperatures have deleterious effects on oocyte developmental competence. The antioxidant and autophagy-related properties of 5-aminolevulinic acid (5-ALA) gives the compound a broad range of biological activities. This study aimed to evaluate the effects of: 1) a high temperature-humidity index (THI) on the developmental competence of bovine oocytes, and 2) 5-ALA administration in combination with sodium ferrous citrate (SFC) during in vitro maturation (IVM) on bovine oocyte developmental competence evaluated at high THI. Bovine ovaries were collected from a local slaughterhouse at moderate environmental temperature (MT; THI of 56.2) and high environmental temperature (HT; THI of 76.7) periods; cumulus-oocyte complexes (COCs) were aspirated from medium-sized follicles, matured in vitro for 22 h, fertilized, and cultured for 10 days. For COCs collected during the HT period, 0 (control), 0.01, 0.1, 0.5, or 1 µM 5-ALA was added to the maturation medium in combination with SFC at a molar ratio of 1:0.125. The results showed that HT adversely affected blastocyst and hatching rates compared with MT. Adding 5-ALA/SFC (1 µM/0.125 µM) to the maturation medium of oocytes collected during the HT period improved cumulus cell expansion and blastocyst rates compared with the no-addition control. In conclusion, this study showed that high THI can disrupt bovine oocyte developmental competence. Adding 5-ALA to SFC ameliorates this negative effect of heat stress and improves subsequent embryo development.
高温对卵母细胞的发育能力有不良影响。5-氨基酮戊酸（5-ALA）具有抗氧化和自噬相关特性，使其具有广泛的生物学活性。本研究旨在评估以下两种情况的影响：1）高温高湿指数（THI）对牛卵母细胞发育能力的影响，2）5-ALA 与柠檬酸亚铁钠（SFC）联合使用对牛卵母细胞在高 THI 下进行体外成熟（IVM）时的发育能力的影响。本研究在中等环境温度（MT；THI 为 56.2）和高环境温度（HT；THI 为 76.7）时期从当地屠宰场采集牛卵巢；从中等大小的卵泡中抽吸卵丘-卵母细胞复合物（COCs），在体外成熟 22 小时，受精，并培养 10 天。对于在 HT 期采集的 COCs，在成熟培养基中添加 0（对照）、0.01、0.1、0.5 或 1 μM 5-ALA，并与摩尔比为 1:0.125 的 SFC 联合添加。结果表明，与 MT 相比，HT 对囊胚和孵化率有不利影响。与无添加对照组相比，在 HT 期采集的卵母细胞成熟培养基中添加 5-ALA/SFC（1 μM/0.125 μM）可提高卵丘细胞扩张率和囊胚率。综上所述，本研究表明，高 THI 可破坏牛卵母细胞的发育能力。向 SFC 添加 5-ALA 可减轻热应激的负面影响，提高随后的胚胎发育。
