Effects of oleic acid in cultured oocytes and/or embryos on the biosynthesis and abundance of transcripts involved in prostaglandin F2± and E2 synthesis

• Grant number: 23/08146-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): September 01, 2023
• Effective date (End): August 31, 2024
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Claudia Maria Bertan Membrive
• Grantee: Maria Eduarda Rocha Pinto
• Host Institution: Faculdade de Ciências Agrárias e Tecnológicas. Universidade Estadual Paulista (UNESP). Campus de Dracena. Dracena , SP, Brazil

Abstract

Early embryonic mortality, caused between the 14th and 19th days after fertilization, determines 20to 40% losses in female beef cattle. The reduction of such mortality, by favoring thematernal-fetal recognition, becomes of fundamental economic interest in breeding operations.Strategies for this aim to reduce the ability to synthesize PGF2± by the maternal endometrium and/ormaximize the anti-luteolytic stimulus induced by the conceptus, including increasing PGE2 synthesis.In the period between the 14th and 19th days after fertilization, the reduction in PGF2± synthesis combined withto the increase in the production of PGE2 characterize a beneficial condition for the establishment of pregnancy.Oleic acid (C18:1 cis-9; unsaturated omega-9 fatty acid) determines changes in the metabolic pathwayof n-6 polyunsaturated fatty acid in the biosynthesis of eicosanoids, including prostaglandins (PG).Supplementation with oleic acid in cell culture media has been reported to affect the synthesis ofPG, however this effect was not evaluated in the culture of bovine oocytes and embryos produced in vitro.The hypothesis is that oleic acid supplementation in the in vitro oocyte maturation culture medium(IVM) and in vitro embryo culture (IVC) increases PGE2 synthesis and reduces PGF2± synthesisby altering the abundance of transcripts involved in PG synthesis. The aim is to determine the effectsof oleic acid supplementation in IVM or CIV on the synthesis of PGE2 and PGF2± and on the abundanceof transcripts involved in the synthesis of PG (PTGER2, PTGER4, PTGES1, PLA2G10, PTGS2,PTGES2, AKR1B1, AKR1C4). Oocytes will be placed in 4-well plates, containing 25oocytes/well equally distributed in one of the four treatments, where they will be matured in 500µL IVM base medium/well supplemented or not with oleic acid (Sigma O1383) in differentconcentrations (0, 500, 750 or 1000 µM) and the CIV will be continued in 500 µL of base medium toCIV/well for all treatments (Experiment 1) and, 25 oocytes/well evenly distributedin one of the four wells where they will be matured in vitro (IVM) in 500 µL IVM base medium/well and the CIVwill be continued in 500 µL base medium for CIV/well supplemented or not with oleic acid indifferent concentrations - 0, 500, 750 or 1000 µM (Experiment 2). 8 repetitions will be performedexperimental for the IVM and 8 experimental repetitions for the CIV, where each repetition will be cultivatedinitially 25 oocytes per treatment group. The concentrations of PGE2 and PGF2± in the culture mediumwill be determined by enzyme-linked immunosorbent assay - ELISA. The abundance of transcripts will beevaluated by RT-qPCR. Statistical analysis will be performed by SAS PROC MIXED. consideringthe economic losses caused by early embryonic mortality in the creation phase, if it comes tobe proven a beneficial effect of such supplementation, such concept will enable the determination offield strategies that can reduce early embryonic mortality and, in this way, improveconception rates in fixed-time artificial insemination (FTAI) programs andfixed-time embryos (FET).