Retinol lowers the oxidative stress in vitrified ovine preantral follicle

The study evaluated the effect of supplementation of retinol in the vitrification solution on the lipid peroxidation and mRNA expression of SOD1 and SOD2 in vitrified cultured follicles. Preantral follicles (200-300 μm) were isolated from the sheep ovaries and distributed separately to the vitrification medium with and without 5μM of retinol (Control fresh group was without vitrification and supplementation of retinol). After a week, the follicles were thawed and subjected to in vitro culture (IVC) for 6 and 12 days. The level of malondialdehyde (MDA), as well as the mRNA expression of superoxide dismutase (SOD1 and SOD2) were assessed at day 6 and day12 of culture period. On day 6 of IVC, MDA concentration was significantly (P<0.05) higher in vitrified group, in comparison to vitrified group with 5μM of retinol and control fresh groups. However, no significant differences in MDA concentration were found among the groups at day 12 of IVC. The mRNA expression level of SOD1 at day 6 differed among the groups and was significantly (P<0.05) higher in vitrified and vitrified with retinol groups compared to the control. The expression pattern of SOD2 was significantly increased in vitrified with retinol group compared to the other groups at day 6 of IVC but expression level decreased (P<0.05) at day 12 in both vitrified groups when compared to the fresh control group. Lowering the vitrification-induced lipid peroxidation of preantral follicles by retinol supplemented vitrification medium may be mediated by increasing SOD expression during IVC.