ROCK Inhibitor During Hypothermic Storage Improves Re-Expansion Rate and Quality of Goat Blastocysts

Abstract

Embryos can be produced in nonheat stress conditions and transported by air to designated destinations using hypothermic and chilled storage procedures. Therefore, improvement of efficiency of these processes may have an important impact on the dairy industry. The aim of this study was to evaluate the viability of embryos treated with ROCK inhibitor (Y-27632) during 4 days of hypothermic storage of goat blastocysts. In this study, vitrification was used as a standard model of cryopreservation. Treatment with ROCK inhibitor (Y-27632) significantly improved the re-expansion rate of blastocyst postwarming compared with treatment with Y-26732, but it was lower than the re-expansion rate in vitrified/warmed blastocysts. The quality of blastocysts in terms of total cell number (TCN) was significantly higher in the control group than in treatment groups, but it was similar between Y-26732, Y-27632, and vitrification groups. The relative expression of BAX, as a proapoptotic marker, was similar between all the groups, whereas the relative expression of BCL2 as an antiapoptotic marker was significantly higher in the Y-26732 group. The rate of TUNEL positive cells was similar between Y-26732 and Y-27632 groups. Thus, our results reveal that addition of Y-27632 improves the re-expansion rate of hypothermic stored embryos possibly through stabilizing the cytoskeleton structure such as intermediate filaments, which prevents the formation of cell membrane blebbing and cytoplasmic fragmentation.