Prostaglandin E2 affects in vitro maturation of bovine oocytes
Dorota Boruszewska, Ilona Kowalczyk‐Zieba, Katarzyna Suwik, Joanna Staszkiewicz‐Chodor, Joanna Jaworska, Krzysztof Łukaszuk, Izabela Wocławek-Potocka
Abstract
Abstract The role of prostaglandin E 2 (PGE 2 ) in the successful resumption of oocyte meiosis and cumulus expansion has been well-documented. However, there remains very little information available on the influence of PGE 2 on other processes that occur during oocyte maturation. In this study, we supplemented a maturation medium with PGE 2 and monitored oocyte quality markers, glucose metabolism, mitochondrial status, oxidative stress, and apoptosis in the cumulus-oocyte complexes (COCs), using a well-established in vitro model of embryo production in cattle. We found that this increased availability of PGE 2 during maturation led to an increase in the expression of genes associated with oocyte competence and improved the quality of blastocysts produced. Prostaglandin E 2 also appeared to stimulate glucose uptake and lactate production in the COCs, both influencing the expression of enzymes involved in glycolysis and the hexosamine biosynthetic pathway. We found that PGE 2 reduced intracellular reactive oxygen species levels, and simultaneously increased glutathione concentration and stimulated antioxidant gene expression in the oocyte. These results indicate that PGE 2 has an important role in the protection of oocytes against oxidative stress. Mitochondrial membrane potential was also improved in PGE 2 -treated oocytes, and there was a reduction in the occurrence of apoptosis in the COCs. Promotion of an anti-apoptotic balance in transcription of genes involved in apoptosis was present in both oocytes and the cumulus cells. In summary, PGE 2 could represent a novel autocrine/paracrine player in the mechanisms that can facilitate successful oocyte maturation and oocyte survival in the cow.