RESUMO
The aim of the study was to compare the effects of two different concentrations of cryoprotectants by cryotopvitrification on survival, developmental capacity and Heat shock protein 72 [Hsp72] expression of two-cell mouse embryos. In this experimental study, transcript analysis of Hsp72 gene was performed on non-vitrified and vitrified 2-cell mouse embryos via a nested quantitative polymerase chain reaction [nqPCR] subsequent to normalization with Hprt1 as the reference gene. The different cryoprotectant combinations were 15% [vit[1]:7.5% of each ethylene glycol [EG] and dimethyl sulfoxide [DMSO], 30% [vit[2]:15% EG + 15% DMSO] and control group with no cryoprotectants. Vitrified and fresh 2-cell embryos were cultured to obtain cleavage and blastocyst formation rates. The results were analyzed via one-way analysis of variance and the mean values were compared with least significant difference [LSD] [p< 0.05]. The relative expression of Hsp72 in vit2 [30% v/v] was significantly higher than vit[1] [15% v/v]. Survival rates were the same for both vitrification treatments and significantly lower than the control group. Cleavage and blastocyst rates in vit[1] were significantly higher than vit[2] while those in two vitrified groups were significantly lower than the control group. Our developmental data demonstrated that vit[1] treatment [7.5% EG and 7.5% DMSO] was more efficient than vit[2] [15% EG and 15% DMSO] in mouse embryos. The cryotopvitrification with two concentrations of cryoprotectants caused the relative changes of Hsp72 transcript level, but the stability of the gene in vit[1] was significantly higher than vit[2] and closer to the fresh 2-cell embryos