Pre-incubation with levocarnitine alleviates vitrification and thawing damage in mouse oocytes.

BACKGROUND: Vitrification of mammalian oocytes is an important means of preserving female reproductive capacity. However, existing technical solutions cannot guarantee recovery rate, fertilization, and developmental potential of vitrified oocytes. Recognized consequences include energy consumption during vitrification and thawing processes, and damage to organelles caused by the formation of ice crystals. In this study, we explore whether incubating with levocarnitine (LC) before vitrification can improve its warming outcomes. RESULTS: Supplementing 2 mg/mL LC can significantly improved recovery rate of warmed oocytes (p < 0.01) and shortened morphological recovery time (p < 0.001). Gene difference analysis showed that supplementing LC altered gene expression related to energy metabolism, autophagy, and cytoskeleton. Further experimental testing showed that supplementing LC increased adenosine triphosphate (ATP) levels (p < 0.05), decreased reactive oxygen species (ROS) levels (p < 0.001), and maintained the stability of the spindle chromosome structure. On this basis, both lipid oxidation (p < 0.01) and autophagy levels (p < 0.0001) in oocytes decreased, and the quality of embryos developed from warmed oocytes was improved (p < 0.05). CONCLUSION: Supplementation of LC to mouse oocytes before vitrification can improve their warming outcomes, which is related to the changes in lipid droplet distribution in oocytes caused by LC by improving lipid metabolism.