Efeito da modulação da Acil-Coa Sintetase de cadeia longa no desenvolvimento, qualidade e criotolerância de embriões bovinos produzidos in Vitro

Abstract

In vitro embryo production (PIVE) has significantly contributed to the exploitation of the potential of genetically superior animals and to the increase of the reproductive efficiency of the herds, giving Brazil a prominent position in comparison to the other countries. However, despite being consolidated, the technique still presents some challenges such as the reduced survival of the PIVE embryos after freezing. One of the factors identified as crucial in this regard is the high lipid content of these embryos when compared to their in vivo counterparts. In this sense, the objective of this work was to evaluate the development of bovine embryos produced in vitro after supplementation of the culture medium with long chain Acil-CoA synthetase modulators, a family of enzymes that participate directly in the activation of fatty acids. The embryos were cultivated divided into four groups: positive supplementation (ACS +) with GW3965 hydrochloride, negative supplementation (ACS-) with Triacsin C, association of both modulators (ACS ±) and control. There was no difference (P> 0.05) in production rates among the different groups. The cytoplasmic lipid content was increased (P <0.05) in ACS + and reduced (P <0.05) in ACS- in relation to the control group, whereas the membrane phospholipid profile was not altered by the treatments. The total number of blastomers did not differ between groups (P> 0.05), however, the highest number of apoptotic cells was found in ACS- when compared to the control group. After vitrification, re-expansion rates did not differ (P> 0.05) 12 h after recultivation. At 24 h, quality I embryos showed the best hatched rates in the ACS + and control groups, and at 48 h the ACS + group equaled the hatched rates of their embryos of grades I, II and III. The relative abundance of the level of gene transcripts associated with lipid metabolism (ACSL3, ACSL6, ACAT1, SCD and AUH), thermal shock (HSP90AA1 and HSF1), oxidative stress (GPX4), angiogenesis (VEGF), among other genes important for development embryo was affected by at least one of the treatments. Thus, the effectiveness of the treatments in modulating the level of gene transcripts of members of the long-chain Acil-Coa synthetase family and in the cytoplasmic lipid content was identified. The negative modulation of ACS- and the consequent reduction in lipid content were not effective in increasing embryonic cryotolerance, whereas ACS + restored survival rates after vitrification of embryos with low quality, making them equivalent to the embryos of excellent quality.