The apoptotic inhibitor z-DEVD-fmk improves the viability and maturation rates of Iberian red deer oocytes while reducing apoptotic markers

The main drawback in developing in vitro embryo production (IVP) systems in wild species, such as the Iberian red deer, is that access to these animals is usually restricted, and long distances from the collection site to the laboratory are usually inevitable. Prolonged ovary storage is known to negatively influence the quality and developmental competence of the oocytes used for IVP. To overcome this issue, we evaluated the effect of adding a caspase-3 inhibitor, z-DEVD-fmk, to the in vitro maturation media to improve the quality and developmental potential of Iberian red deer oocytes. Oocytes were in vitro matured with and without z-DEVD-fmk, and the following parameters were analyzed: viability, early apoptosis, caspase-3 activity, DNA fragmentation, and relative abundance of mRNA transcript related to apoptosis. Moreover, oocyte maturation and blastocyst rates were also assessed. The results showed that z-DEVD-fmk decreased early apoptosis (inhibitor= 44.44 ± 3.6% vs. control= 60 ± 2.79%), DNA fragmentation (inhibitor= 57.83 ± 1.91% vs. control= 74.62 ± 1.91%), caspase-3 activity (inhibitor= 41.88 ± 3.42% vs. control= 67.10 ± 3.42%) and the relative abundance of TP53 and ITM2B transcripts, as well as increased the number of live (inhibitor= 41.48 ± 2.32% vs. control= 20 ± 1.8%) and in vitro-matured oocytes (inhibitor= 88.18 ± 1.99% vs. control= 74.01 ± 1.99%) rates. Nevertheless, the blastocyst production was not different between both experimental groups (inhibitor: 7.35 ± 2.30 vs. control: 13.77 ± 2.30). The supplementation of z-DEVD-fmk to the maturation medium improved the quality of Iberian red deer oocytes. Further research and alternative strategies are needed to evaluate if this inhibitor could still enhance the developmental potential of oocytes during prolonged ovarian transport.