Assessment of Mitochondrial Function and Developmental Potential of Mouse Oocytes after Mitoquinone Supplementation during Vitrification

Vitrification negatively affects the mitochondrial membrane potential (..m) in oocytes while also leading to increased reactive oxygen species (ROS), ATP depletion and induction of apoptosis in oocytes. Mitoquinone (MitoQ) is an antioxidant that protects mitochondrial membrane integrity from ROS. This study examined the effect of adding MitoQ to vitrification medium on mitochondrial function and embryo development in vitrified oocytes. Metaphase II (MII) stage oocytes were collected from NMRI mouse ovaries and preincubated for 20 min in a medium containing 0.02 mu M of MitoQ. Next, oocytes were vitrified in medium supplemented with 0.02 mu M of MitoQ (treatment group). The control group was processed in the same way but without exposure to MitoQ. After warming, oocyte survival rate, Delta psi m, cytoplasmic ROS and glutathione (GSH) levels and gene expression levels (Bcl2, BAX, and caspase3) were measured. In addition, the vitrified oocytes were fertilized in-vitro to assess developmental competence. The results showed that MitoQ improved survival and Delta psi m in treated vitrified oocytes. Treated oocytes showed lower ROS levels and higher GSH levels than did the control group. Furthermore, mRNA expression of the Bax/Bcl2 ratio and caspase3 were significantly lower in treated oocytes. These findings indicate that medium supplementation with 0.02 mu M of MitoQ during vitrification can improve oocyte survival and developmental competency in mouse oocytes.