Effect of a low ethanol concentration during in vitro maturation of bovine oocytes and subsequent embryo development

• Published in: Theriogenology Vol. 208; pp. 158 - 164
• Main Authors: Sato, Takuya, Hamazaki, Mao, Inoue, Yuki, Aoki, Sogo, Koshiishi, Yuichi, Shirasuna, Koumei, Iwata, Hisataka
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.09.2023; Elsevier BV
• Subjects: Adenosine Triphosphate; amino acid metabolism; animal reproduction; Animals; carbon metabolism; Cattle; Cumulus Cells; DNA, Mitochondrial; embryogenesis; Embryonic Development; Ethanol; Ethanol - pharmacology; fatty acids; Female; Gene expression; gene expression regulation; gluconeogenesis; Glucose; Glucose - pharmacology; glycolysis; H3K9 methylation; histones; In Vitro Oocyte Maturation Techniques; In Vitro Oocyte Maturation Techniques - veterinary; lipid content; Lipids; membrane potential; Mitochondria; mitochondrial DNA; mitochondrial membrane; Oocyte maturation; Oocytes; RNA; sphingolipids; Mitochondria; Ethanol; Gene expression; H3K9 methylation; Oocyte maturation
• ISSN: 0093-691X; 1879-3231; 1879-3231
• DOI: 10.1016/j.theriogenology.2023.06.007

The present study investigated the effects of low ethanol exposure on bovine oocytes. Cumulus-oocyte complexes (COCs) were aspirated for the antral follicles of slaughterhouse-derived ovaries. These COCs were incubated in maturation medium containing 0, 0.1, and 0.2% ethanol for 21 h and subjected to fertilization and in vitro development, and then the rates of nuclear maturation, mitochondrial DNA copy number (Mt-cn) and protein (TOMM40), ATP content and lipid content in oocyte, fertilization, and blastulation were examined. Furthermore, COCs were incubated with 0 or 0.1% ethanol and then mitochondrial membrane potential (MMP) and the glucose consumption of COCs was determined. In addition, gene expression in oocytes was examined by RNA sequencing. Ethanol (0.1 and 0.2%) increased Mt-cn and Mt-protein levels whereas 0.2% ethanol increased the blastulation rate and ATP content in oocytes and decreased lipid content in oocytes. Ethanol (0.1%) increased MMP in oocytes and decreased glucose consumption of COCs. Eight stage embryos derived from 0.1% ethanol treated oocytes had higher levels of trimethyl-H3K9 compared with that of nontreated counterpart. RNA sequencing revealed that differentially expressed genes were associated with glycolysis/gluconeogenesis, carbon metabolism, sphingolipid metabolism, amino acid metabolism, and fatty acid degradation pathways. In conclusion, even 0.1% concentrations of ethanol during in vitro maturation considerably affects oocyte metabolism and histone configuration of embryos. •Even low concentration of ethanol affects metabolism and developmental ability of oocytes.•RNA sequencing revealed genes affected by low ethanol exposure.•Mitochondria are major target of ethanol exposure.