Free fatty acid treatment of mouse preimplantation embryos demonstrates contrasting effects of palmitic acid and oleic acid on autophagy

Abstract

Treatment of mouse preimplantation embryos with elevated palmitic acid (PA) reduces blastocyst development, while co-treatment with PA and oleic acid (OA) together rescues blastocyst development to control frequencies. To understand the mechanistic effects of PA and OA treatment on early mouse embryos, we investigated the effects of PA and OA, alone and in combination, on autophagy during preimplantation development in vitro. We hypothesized that PA would alter autophagic processes and that OA co-treatment would restore control levels of autophagy. Two-cell stage mouse embryos were placed into culture medium supplemented with 100 μM PA, 250 μM OA, 100 μM PA and 250 μM OA, or KSOMaa medium alone (control) for 18 - 48 h. The results demonstrated that OA co-treatment slowed developmental progression after 30 h of co-treatment but restored control blastocyst frequencies by 48 h. PA treatment elevated LC3-II puncta and p62 levels per cell while OA co-treatment returned to control levels of autophagy by 48 h. Autophagic mechanisms are altered by non-esterified fatty acid (NEFA) treatments during mouse preimplantation development in vitro, where PA elevates autophagosome formation and reduces autophagosome degradation levels, while co-treatment with OA reversed these PA-effects. Autophagosome-lysosome co-localization only differed between PA and OA alone treatment groups. These findings advance our understanding of the effects of free fatty acid exposure on preimplantation development, and they uncover principles that may underlie the associations between elevated fatty acid levels and overall declines in reproductive fertility.

Associations of fertility parameters with fatty acids and DNA methylation in Mexican women undergoing in vitro fertilization

“…Also, impaired FA metabolism coincides with high fat diet-associated ovarian dysfunction 18 . Exposure of cultured early embryos to speci c FA revealed that palmitic acid (PA) slowed developmental progression and induced autophagy, while OA reversed those responses 19 .…”