Supplementation with linolenic acid and L-carnitine during oocyte maturation: effects on cellular metabolism, developmental potential and cryotolerance of bovine embryos produced in vitro

Abstract

In order to improve the results of cryopreservation of bovine embryos produced in vitro (IVP), this study will be conducted with the main objective of evaluating the impact of supplementation of maturation medium with linolenic acid (ALA), associated with or without L-carnitine, on the in vitro maturation (IVM) and oocyte quality, especially with regard to lipid metabolism and the development and resistance to cryopreservation of embryos produced after in vitro fertilization. In a first step of the study, it will be conducted a dose-response experiment to determine the optimal concentrations of ALA (0, 10, 50 or 100 mM) and L-carnitine (0, 1, 5 or 10 mM) that must be added to the medium IVM, supplemented with 10% FBS and 0.6% BSA. The effects of ALA and L-carnitine on the nuclear and cytoplasmic maturation, as well as the intracellular lipid accumulation of bovine oocytes, oxidation potential of the medium and production of intracellular reactive oxygen species will be assessed. In a second step, it will be assessed the effect of supplementation with ALA, associated with or without L-carnitine (concentrations will be defined in the previous step), during IVM on subsequent in vitro embryo development, intracytoplasmic lipid accumulation and cryotolerance. The rate of cleavage (48 hpi) and embryo development to the blastocyst stage will be assessed on D7 of CIV and the blastocysts will be vitrified. Subsequently, they will be thawed and embryonic survival will be assessed. Also in this step, we will evaluate the regulation of expression of genes involved in lipid metabolism (regulation of lipogenesis: SCD1, FAS and SREBP1; regulation of metabolic pathway B - oxidation: CPT1B and CPT2) in oocytes and embryos supplemented with ALA and / or L-carnitine during IVM. (AU)