Effect of Anti-Müllerian Hormone on Oocytes In Vitro Maturation in Sheep

Improvement in the in vitro maturation (IVM) of oocyte quality is a gateway to enhancing the efficiency of in vitro embryo production. The anti-Müllerian hormone (AMH) is a crucial hormone secreted by granulosa cells that effectively suppresses primordial follicle recruitment and regulates follicular growth and development. This study was designed to investigate the role of AMH on the IVM of sheep oocytes. In this current study, oocytes in vitro were cultured in media supplemented with AMH. We comprehensively analyzed the impact of AMH on various developmental parameters of sheep oocytes, such as cellular activity, cortical granules (CGs) migration, cytoskeleton and mitochondrial function of oocytes. Furthermore, Smart-seq2 single-cell RNA sequencing (scRNA-seq) was employed to elucidate the oocytes' development. The results showed that treatment with 100 ng/mL improved the maturation rate of the oocytes, the normal distribution rate of cortical granules and mitochondrial function, while reducing the rate of spindle abnormalities in oocytes. A total of 741 differentially expressed genes (DEGs) were observed between the FSH_12 h and AMH_12 h groups, and 746 DEGs were observed between the FSH_24 h and A+F groups. KEGG pathway analysis revealed that the FSH_12 h and AMH_12 h groups significant enrichment in DEGs were associated with p53, MAPK, PI3K-Akt and TGF-beta signaling pathways, and the FSH_12 h and AMH_24 h groups significant enrichment in DEGs were associated with cAMP, AMPK, Hedgehog and estrogen signaling pathways. These findings suggest that AMH may regulates oocytes IVM via several candidate signaling pathways. Our results provide preliminary clues for exploring the regulatory mechanism of sheep oocyte maturation and optimizing relevant culture systems.