Abstract
In the last decade, the in vitro production (IVP) of bovine embryos became a widely used biotechnology in national livestock. According to data published by the International Embryo Transfer Society (IETS), 373,836 in vitro produced bovine embryos were transferred in 2011, of which 85% were produced in Brazil (IETS 2012). However, the in vitro production system, even though technically feasible, causes cellular and molecular changes on the embryos, and has a lower efficiency than desirable, showing blastocyst rates ranging from 30 to 50 % of immature oocytes. One of the steps with greater impact on oocyte competence to reach the blastocyst stage is the in vitro maturation (IVM). Previous studies conducted by our research group demonstrated deficiencies in relation to migration and amount of active mitochondria and lipid droplets during IVM when compared to the in vivo process. Assuming that oocyte mitochondrias are responsible for energy intake until the blastocyst stage , and that fatty acids oxidation occurring in mitochondria is the main cellular mechanism responsible for the energy supply to the oocyte and embryo development, the activity of both organelles is crucial for successful IVP embryos. There are evidences ( WU et al., 2011 , Dunning et al., 2012 YAMAGUCHI et al., 2012 and CHANKITISAKUL et al., 2013 ) that ²-oxidation modulator substances of, such as L-carnitine and bezafibrate, could stimulate oxidative process and lead to an increase of embryo production rates. Thus, this study aims to compare the mitochondrial activity and lipid metabolism between the in vivo embryo production and IVP, as well as determine the effect of adding mitochondrial oxidation modulators (L- carnitine and bezafibrate) during IVM on in vitro production rates. For this purpose, lipid and mitochondrial behavior, ²-oxidation and cellular stress factors during maturation and embryo development in different conditions of embryonic production will be evaluated. From the results of this project, we expect to understand the effects of in vitro systems on ²-oxidation and mitochondrial lipid metabolism, and also increase the embryo production by adding mitochondrial oxidation modulators that do not increase cellular oxidative stress. (AU)
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