Influence of resveratrol pretreatment on thawed bovine embryo quality and mitochondrial DNA copy number.

This study addresses the hypothesis that SIRT1 upregulation prior to cryopreservation helps in recuperation from cryoinjury and improves the embryo quality. Bovine blastocysts were produced in vitro, and at Day 6 or 7 after fertilization, the blastocysts were cultured with 0 or 1 μM resveratrol for 6 or 24 h. This short duration of resveratrol treatment did not affect the embryo development or the grade of the blastocysts. However, both the durations of resveratrol treatment (6 h or 24 h) significantly increased the expression levels of SIRT1. When embryos pre-treated with resveratrol (0 or 1 μM) were cryopreserved and subsequently thawed, the hatching rates following 48 h of incubation were significantly higher for the resveratrol-treated embryos than for vehicle-treated embryos. Moreover, the resveratrol pretreatment significantly increased the copy number of mitochondrial DNA in the embryos, irrespective of the treatment durations. The in vitro-produced embryos at 6 days of insemination and the in vivo-developed embryos, which were collected from the donor cows at 6.5 days of insemination, were treated with resveratrol for 6 or 24 h prior to cryopreservation, respectively. The resveratrol pretreatment (for 6 or 24 h) resulted in high conception rate after thawing and transfer to the recipients, in both the in vivo and in vitro-produced embryos. In conclusion, our results suggest that pretreatment of bovine embryos with resveratrol improves the quality of embryos after cryopreservation and thawing probably through mitochondrial synthesis.