Antioxidant-supplemented media modulates ROS by regulating complex I during mouse oocyte maturation

In Vitro Oocyte Maturation (IVM) is a technique used to mature oocytes in laboratory setting. However, IVM can lead to an imbalance of reactive oxygen species (ROS), which can damage the oocytes. To prevent this, antioxidants are added to the culture medium. How these antioxidants affect Complex I, a crucial ROS-producing protein within the mitochondrial membrane, remains uncertain. To address this gap, our study aimed to achieve two key objectives. First, we investigated, for the first time, the Complex I expression during mouse oogenesis. Second, we examined the influence of an antioxidant-containing medium on Complex I and ROS levels. Germinal vesicle (GV)-stage oocytes were incubated in culture media containing acetyl-l-carnitine (ALC), α-lipoic acid (ALA), MitoQ, N-acetyl-l-cysteine (NAC) until the metaphase I (MI) and metaphase II (MII) stages. Complex I and ROS levels increased in MI and MII oocytes. Additionally, ALA and NAC increased Complex I and ROS levels, while MitoQ decreased these levels in MI and MII oocytes. Interestingly, ALC did not affect MI oocytes, but decreased the Complex I and ROS levels in MII oocytes. By elucidating the interplay between antioxidants, Complex I, and ROS during oogenesis, we pave the way for future research to improve female fertility.