Preliminary research on the effect of linolenic acid on human oocyte maturation

Abstract

Objective: To investigate the effects of exogenous α-linolenic acid (ALA) on in vitro maturation (IVM) and developmental competence of human oocytes. Methods: Experiment 1 examined the effects of ALA at different concentrations (0 [control], 10, 50, 100, and 200 μmol/L) in the IVM medium on oocyte maturation. Treatment with 50 μmol/L ALA significantly accelerated oocyte maturation (P < 0.05) and resulted in significantly higher mitochondrial DNA (mtDNA) copy number compared to the control. Hence, 50 μmol/L ALA was selected for combination with follicular fluid (FF) to investigate oocyte developmental potential. mtDNA of the matured oocyte was analyzed by real-Time polymerase chain reaction. Experiment 2 investigated the effects of FF with optimal ALA concentration (Group A: ALA + FF + IVM medium) or without ALA (Group B: FF + IVM medium) on oocyte maturation, fertilization, 2 pronuclear cleavage, and embryo and blastocyst development. Malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were measured for maturation medium from Group A, Group B, and Group C (control group, IVM medium only). Results: Treatment with 50 μmol/L ALA obviously accelerated oocyte maturation (P < 0.05) and resulted in significantly higher mtDNA copy number (P < 0.05) in the matured oocytes compared to the control (0 μmol/L ALA). Supplementation of 50 μmol/L ALA and FF (Group A) obviously increased the total maturation rate than FF-Treated group (Group B) which has higher (P < 0.05) total maturation rate than that of Group C. However, no significant differences were observed in fertilization, embryo availability, and blastocyst production among Group A, B, and C. Treatment with 50 μmol/L ALA decreased the level of MDA (P < 0.05), but had no effect on the activity of SOD in the IVM medium. Conclusions: Our results suggested that the treatment with 50 μmol/L ALA during IVM improves maturation in human oocytes. It is also likely to improve embryo availability and blastocyst formation. This might be associated with the alteration of mtDNA replication (increased mtDNA copy number) and the reduction of oxidative stress (reduced MDA level).