Modulating Developmental Competence in Ovine Oocytes: Role of Sodium Hydrosulfide as an Exogenous Hydrogen Sulfide...

The developmental competence of oocytes is crucial for successful fertilization and embryonic development; however, optimizing this capacity remains challenging. Hydrogen sulfide (H₂S), a gasotransmitter recognized for its cytoprotective and antioxidant properties, has the potential to enhance oocyte quality. This study investigated the effects of sodium hydrosulfide (NaHS), an exogenous H₂S donor, on the developmental competence of ovine oocytes in both conventional (C-IVM) and biphasic in vitro maturation (Pre-IVM) systems. Immature ovine oocytes were cultured in C-IVM medium supplemented with increasing NaHS concentrations (0-10 mM) to determine the optimal concentration based on redox state, mitochondrial status, and developmental outcomes. Subsequently, the effects of NaHS during the Pre-IVM phase of the biphasic system were evaluated, focusing on meiotic arrest, cytoplasmic maturation, and developmental competence. The results revealed that 2.5 mM NaHS during C-IVM significantly improved oocyte quality by reducing reactive oxygen species (ROS) levels, increasing glutathione (GSH) content, and enhancing blastocyst rates. Furthermore, a 6-h exposure to 2.5 mM NaHS during Pre-IVM did not alter germinal vesicle (GV) rates and cyclic AMP levels but significantly decreased ROS levels and increased mitochondrial mass index at both 6 and 24 h. In the biphasic system, 2.5 mM NaHS notably elevated blastocyst rates. These findings suggest that NaHS could serve as a promising supplement to improve IVM efficiency and embryonic development, providing valuable insights for assisted reproductive technologies.