Propionic Acid Supports the Development of Oocytes Derived from Bovine Early Antral Follicles

The present study investigated the effects of propionic acid (PA) supplementation during the in vitro growth of oocytes derived from bovine early antral follicles (EAFs) on oocyte quality and granulosa cell (GC) characteristics. Oocyte-GC complexes (OGCs) were collected from bovine ovaries and cultured for 14 days in medium supplemented with or without 0.01 mM PA. Oocytes and GCs obtained from large antral follicles were used as in vivo controls. Oocytes cultured with PA exhibited higher nuclear maturation and fertilization rates than those cultured without PA. PA supplementation increased lipid content and ATP levels in both oocytes and GCs and enhanced glucose consumption in OGCs. However, compared with in vivo-grown oocytes, in vitro-grown oocytes showed lower ATP levels, lipid content, mitochondrial membrane potential, and fertilization ability. RNA-seq followed by K-medoids clustering analysis revealed that PA-induced genes in GCs showing expression patterns similar to those in vivo were mainly associated with oxidative phosphorylation, whereas genes showing expression patterns distinct from the in vivo profile were associated with the PI3K-Akt signaling pathway. In conclusion, PA improves the quality of in vitro-grown oocytes and is associated with enhanced energy status in both oocytes and GCs. However, some PA-induced gene expression patterns in GCs differed from those observed in vivo.