Protective Effect of Evening Primrose Seed Oil on Viability and Expression of BMP15 and GDF9 Genes in Cultured Oocytes

Background and purpose: Oocyte culture conditions are critical determinants of the success of in vitro fertilization; therefore, the use of compounds that help preserve oocyte quality in the extracellular environment is essential. Evening primrose seed oil (EPO) is a rich source of potent antioxidants, and its role in modulating cytotoxic reactions has been well documented. The aim of the present study was to investigate the impact of EPO on the quality of oocytes cultured in vitro. Materials and methods: In this experimental study, 35 female Naval Medical Research Institute (NMRI) mice, aged 5 to 6 weeks, were randomly assigned to five groups. To induce ovulation, the mice were injected with gonadotropin hormones, and 48 hours later, they were euthanized via cervical dislocation. Oocytes were extracted from the ovaries and categorized into the following groups: a control group (no treatment), an MO-treated group, an EPO-treated group, a group treated with a 50:50 (v/v) mixture of EPO and MO, and a group treated with a 25:75 (v/v) mixture of EPO and MO. Oocyte viability was assessed by counting under an inverted microscope. The expression levels of growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) genes were evaluated using quantitative real-time PCR (qRT-PCR). One-way analysis of variance (ANOVA) followed by Tukey’s post-hoc test was used for statistical analysis. Results: Under EPO treatment, the oocyte viability rate reached 92.3%, representing the highest value observed among all groups. In the EPO-treated group, BMP15 gene expression increased by 1.88 ± 0.06-fold, while GDF9 gene expression increased by 1.36 ± 0.08-fold compared to the control group. In contrast, in the MO-treated group, BMP15 gene expression decreased to 0.52 ± 0.04-fold, and GDF9 gene expression decreased to 0.60 ± 0.02-fold, relative to the control group. Conclusion: Based on the results, evening primrose oil (EPO) may enhance oocyte viability and quality in the culture medium by preserving the expression of GDF9 and BMP15 genes.