The effect of L-carnitine on Oocyte Mitochondrial Activity after Cryopreservation

Mitochondria are cellular organelles required for energy production, vital to reproduction, especially oocyte maturation and fertilization. It has been seen that oocyte cryopreservation (OC) can cause mitochondria damage, aggregation of lipid droplets near mitochondria and endoplasmic reticulum, and cryoinjury. In recent studies use of antioxidants such as L- carnitine can increase the number of active mitochondria and decrease intracellular ROS levels. The present study aimed to determine the beneficial effect of L –carnitine on oocyte mitochondrial activity after vitrification.

In the present experimental study, 6-8 weeks of female NMRI mice were taken from the Royan Institute of Iran and stimulated with 7.5 IU Pregnant Mare Serum Gonadotrophin (PMSG) and 10 IU of human chorionic gonadotropin (HCG) after 48 hours was injected. After stimulation, oocytes were collected, and MII oocytes were selected. A two-step vitrification procedure was done, and 0.6mg/ml of L –carnitine was added to both ES and VS mediums. After two weeks, oocyte thawing was performed, intracellular GSH level was also measured mitochondrial membrane potential was measured. Captured images were analyzed by J software (Version 1.40; and obtained data were analyzed using SPSS Ver.20.

Average difference in intracytoplasmic GSH level in the study group was significantly higher than the control group (P<0.001). So, L –carnitine could successfully increase the oocyte intracytoplasmic GSH level. Also, it has been seen that the LC supplement could successfully grow oocyte mitochondrial function and subsequent mitochondrial membrane potentials(P<0.001).

Adding LC to the cryopreservation media could increase mitochondrial activity, GSH level, and mitochondrial membrane potentials. Adding LC to the cryopreservation could enjoy the beneficial effect of L –carnitine on oocyte mitochondrial activity after vitrification and minimize mitochondrial damage and boost oocyte quality which can lead to successful fertilization and embryo growth.